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Twin 360's

Printed From: TheAMCForum.com
Category: The Garage
Forum Name: AMC V8 Engine Repair and Modifications
Forum Discription: AMC-made V8 engine mechanical, ignition and fuel from basic repair to high-perf modifications
URL: http://theamcforum.com/forum/forum_posts.asp?TID=82815
Printed Date: Feb/22/2018 at 3:56am


Topic: Twin 360's
Posted By: pipefactory
Subject: Twin 360's
Date Posted: Sep/24/2016 at 7:49pm
Anyone ever link 2 360s together crank to crank. I'm doing this on my motorhome. I used 2 dirt track direct crank hubs and redrilled them then a 10 spline input shaft that I cut off.

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Face distorting torque
11.25 @ 116.7 mph



Replies:
Posted By: gremlin1945
Date Posted: Sep/24/2016 at 11:34pm
Why?

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former NHRA #1945

former IHRA #1945

T/SA


Posted By: motorhead_1
Date Posted: Sep/24/2016 at 11:45pm
AMC v12! i like it!

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69 SC/Rambler tribute with 401/th400, 68 Rebel SST, 67 Rebel


Posted By: amxdreamer
Date Posted: Sep/25/2016 at 12:06am
Originally posted by motorhead_1 motorhead_1 wrote:

AMC v12! i like it!
8+8=16 Wink

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Tony
Vancouver, BC
1970 AMX
AMO#10333


Posted By: purple72Gremlin
Date Posted: Sep/25/2016 at 12:18am
A V16.   you will be very familiar with gas stations?


Posted By: maximus7001
Date Posted: Sep/25/2016 at 1:06am
Both engines would need to be internally balanced for this to work. This has been done in drag racing and tractor pull applications. Have not seen it with AMC engines.


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1968 Javelin SST

1997 GMC Safari AWD

2002 Chevy Malibu

1997 Ford Contour

Winnipeg, home of the Jets.


Posted By: 74gremx
Date Posted: Sep/25/2016 at 1:50am
Wasn't there a drag car with two 232's inline?


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1970 Javelin 360/727
1974 Levis Gremlin X 304/904
1964 American Convertible
1974 Matador wagon (parts)
2016 Holden Cruze Equipe
2014 Holden Colorado
"Don't mistake activity for achievement".






Posted By: Boris Badanov
Date Posted: Sep/25/2016 at 6:33am
As long as the harmonic balancers are intact internal balance should be unnecessary.
the only issue I see is you need to phase them at 22.5 degrees to get even firing pulses.

Very cool idea!

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Gremlin Dreams


Posted By: pipefactory
Date Posted: Sep/25/2016 at 7:30am
Originally posted by gremlin1945 gremlin1945 wrote:

Why?
around here you can't get out of town without climbing a long steep hill and I'm always towing something also it's cool.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: pipefactory
Date Posted: Sep/25/2016 at 7:33am
Originally posted by Boris Badanov Boris Badanov wrote:

As long as the harmonic balancers are intact internal balance should be unnecessary.
the only issue I see is you need to phase them at 22.5 degrees to get even firing pulses.

Very cool idea!
wouldn't it have to be 45 degree's I want #1 to fire on the 2nd between 1&8 on the 1st.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: pipefactory
Date Posted: Sep/25/2016 at 7:42am
I need some input on this. I'm keeping the water pump on the front motor and blocking off the rear motors pump and putting 2 hose barbs on the plate. I'm thinking the water comes in the front pump goes out the back of front motors heads into the rear motors water pump block off plate hose barbs to fill both motors then both will keep there own thermostats and will return into 2 side by side aluminum radiators also the lower radiator outlets will be connected and feed the front water pump. How's that?

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: Hurst390
Date Posted: Sep/25/2016 at 8:43am
 I guess it would be easy enough to connect the two engine like you say. Use a bert or similar coupler and add a flange to one end of the input to bolt to the rear engine's balancer.
 In my experience you might want to use an aluminum coupler as the steel is very hard and carbide has a hard time. I had to use a cut-off wheel to open up the bolt pattern on a chevy coupler to work with the rambler crank. And I had to make a bushing to pilot it to the crank. In the future I may machine a ring to make the o.d. bigger and trap the bolts but so far it has been in service for 3 hard seasons on a dirt track.
 As far as cooling. its your project so I haven't spent but a few seconds thinking but I personally wouldn't start out by pumping water from one engine into the other. I would just plumb the rear engine around to two stacked radiators in the front. In a motorhome you probably have room to leave a space between the 2 radiators. Just my quick thoughts on it.
I see a mill,lathe,welder,etc in your future along with a lot of time and imagination. And a single HIGH TORQUE starter...lol
http://s23.photobucket.com/user/Hurst390/media/P1014059.jpg.html" rel="nofollow">
http://s23.photobucket.com/user/Hurst390/media/P1014060.jpg.html" rel="nofollow">
http://s23.photobucket.com/user/Hurst390/media/P1014058.jpg.html" rel="nofollow">




-------------
SC/Hurst Rambler

11.62 120

100% Street Legal


Posted By: pipefactory
Date Posted: Sep/25/2016 at 9:16am
Originally posted by Hurst390 Hurst390 wrote:

 I guess it would be easy enough to connect the two engine like you say. Use a bert or similar coupler and add a flange to one end of the input to bolt to the rear engine's balancer.
 In my experience you might want to use an aluminum coupler as the steel is very hard and carbide has a hard time. I had to use a cut-off wheel to open up the bolt pattern on a chevy coupler to work with the rambler crank. And I had to make a bushing to pilot it to the crank. In the future I may machine a ring to make the o.d. bigger and trap the bolts but so far it has been in service for 3 hard seasons on a dirt track.
 As far as cooling. its your project so I haven't spent but a few seconds thinking but I personally wouldn't start out by pumping water from one engine into the other. I would just plumb the rear engine around to two stacked radiators in the front. In a motorhome you probably have room to leave a space between the 2 radiators. Just my quick thoughts on it.
I see a mill,lathe,welder,etc in your future along with a lot of time and imagination. And a single HIGH TORQUE starter...lol
http://s23.photobucket.com/user/Hurst390/media/P1014059.jpg.html" rel="nofollow">
http://s23.photobucket.com/user/Hurst390/media/P1014060.jpg.html" rel="nofollow">
http://s23.photobucket.com/user/Hurst390/media/P1014058.jpg.html" rel="nofollow">





I already have both mock up blocks and cranks coupled together. I used the same flange but re drilled and my friend counter bored them to center on the crank and balancer. Also going to use 2 starters.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: shootist
Date Posted: Sep/25/2016 at 11:17am
This is very interesting indeed. I want to see some pictures once you get this put together. I am curious as to why would it not be best to just set both motors in synch with each other at 0 degrees and use only one distributor for timing and firing? I have never coupled two engines together but it would seem to me it would be easier to troubleshoot and keep running with a single timing source.



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Posted By: ghinmi
Date Posted: Sep/25/2016 at 2:53pm
Using one distributor would not be successful.  You can't link two plugs together, only one would fire.

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1983 Cherokee - Turbo Hemi autocross/road race


Posted By: Boris Badanov
Date Posted: Sep/25/2016 at 5:09pm
Originally posted by pipefactory pipefactory wrote:

Originally posted by Boris Badanov Boris Badanov wrote:

As long as the harmonic balancers are intact internal balance should be unnecessary.
the only issue I see is you need to phase them at 22.5 degrees to get even firing pulses.

Very cool idea!
wouldn't it have to be 45 degree's I want #1 to fire on the 2nd between 1&8 on the 1st.


I stand corrected!
I have Harleys on the brain.....

Agreed, you would need two distributers.
Individual coils or coil packs might be a better option.

-------------
Gremlin Dreams


Posted By: pipefactory
Date Posted: Sep/25/2016 at 7:33pm
Should have some pics next week. My next step is connecting the blocks. When I'm done I want to Dyno in three steps break in and tune each separate then both together.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: Boris Badanov
Date Posted: Sep/25/2016 at 8:40pm
What are you going to do to place a balancer between the engines?
It will need to buffer both the flywheel of the front engine and
harmonic balancer of the real.

I love the idea, can't wait to see the results.




-------------
Gremlin Dreams


Posted By: FSJunkie
Date Posted: Sep/25/2016 at 9:20pm
Connecting the crankshafts end to end like a true V16 would be a disaster even if there was a dampener between them because the rear crankshaft has to handle twice the torque. The torque of the front engine has to pass through the rear engine.

GMC managed to do it in the early 60's with their V12. It was basically two of their V6's stuck together, but there was way more engineering than that. I'm sure the crankshaft had to be strengthened considerably.

You'd be better off putting the engines back-to back, facing opposite directions but with the crankshafts in line with each other Connect them connect to a center gearbox. You might be able to repurpose an old rear axle. Each engine would power the axle shafts of the axle and you'd take power off the pinion. You might even retain the differential to let each engine balance the load and RPM of the other. It might also be good to put some kind of fluid coupling or torsional dampener between the gearbox and each engine just in case some bizarre vibrations are encountered. Unchecked, they could snap a crankshaft in no time.






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'66 Marlin: 327/T10/3.54 Twin Grip
'72 Wagoneer: 360/TH400/3.31
'73 Ambassador: 360/TF727/3.15
'77 Hornet: 232/TF904/2.73
'84 Eagle: 258/TF904/2.73


Posted By: pipefactory
Date Posted: Sep/25/2016 at 9:56pm
Originally posted by FSJunkie FSJunkie wrote:

Connecting the crankshafts end to end like a true V16 would be a disaster even if there was a dampener between them because the rear crankshaft has to handle twice the torque.
The torque of the front engine has to pass through the rear engine.

GMC managed to do it in the early 60's with their V12. It was basically two of their V6's stuck together, but there was way more engineering than that. I'm sure the crankshaft had to be strengthened considerably.

You'd be better off putting the engines back-to back, facing opposite directions but with the crankshafts in line with each other Connect them connect to a center gearbox. You might be able to repurpose an old rear axle. Each engine would power the axle shafts of the axle and you'd take power off the pinion. You might even retain the differential to let each engine balance the load and RPM of the other. It might also be good to put some kind of fluid coupling or torsional dampener between the gearbox and each engine just in case some bizarre vibrations are encountered. Unchecked, they could snap a crankshaft in no time.





it's been done many times in the past. The spirit of America was supposed to be power by 2-401's. Both engines will have there own balancer's and flex plates. Also running them 45 degrees apart would make a smoother running engine than one by itself. #1 fires on the front motor then 45 degrees later #1 on the rear fires another 45 degrees #8 on the front fires and so on.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: Red20
Date Posted: Sep/26/2016 at 1:03am
What's your plan for cams and exhaust? A pair of performer grind cams would drag a barn at 750 RPM! Quad exhaust or an 8 into 1 into 4" exhaust tubing? Or?

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1969 Javelin SST "Screamin' Banana" - 16k original miles, warm 360, TH-350, Model 20 TracLok, DAILY DRIVER


Posted By: pipefactory
Date Posted: Sep/26/2016 at 5:53am
Originally posted by Red20 Red20 wrote:

What's your plan for cams and exhaust? A pair of performer grind cams would drag a barn at 750 RPM! Quad exhaust or an 8 into 1 into 4" exhaust tubing? Or?
funny you should mention that. I have one Edelbrock in the motor that was in the RV
and just ordered another. 448 and 472 and 214 and 224 at .050. exhaust will be free flow manifolds with 2.5" duals.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: Boris Badanov
Date Posted: Sep/26/2016 at 6:25am
Kenz and Leslie joined flat head Fords in the V-16 manner
back in the 1940's and 1950's.

They ran three Flatties in a stream liner on the salt flats.

Properly balanced it should work well and be reliable.

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Gremlin Dreams


Posted By: scott
Date Posted: Sep/26/2016 at 7:21am
What will you be using for a transmission???


Posted By: pipefactory
Date Posted: Sep/26/2016 at 7:29am
Originally posted by scott scott wrote:

What will you be using for a transmission???


727 I rebuilt for the motorhome. It has extra clutches.

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Face distorting torque
11.25 @ 116.7 mph


Posted By: 6PakBee
Date Posted: Sep/26/2016 at 7:30am
Twin engine applications are nothing new.  In addition to those mentioned, the 'Freight Train' dragster was one I always think of for twin engine combinations.

http://www.thefreighttrain.com/" rel="nofollow - http://www.thefreighttrain.com/

I am still skeptical about long term crankshaft strength (and life) in this application.  I don't know of any example that was intended to be good for 50,000-100,000 mile of dependable, fault free service.  But so what, you want to give it a shot, go for it. Thumbs Up




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The difference between people and AMC's is that they will always be making more people; they won't be making more AMC's

Roger





Posted By: Red Devil
Date Posted: Sep/26/2016 at 12:55pm
A transmission change and/or rear end change (2 speed) for a wider gear spread to get going and stay going would seem to be a simpler and more efficient option ... or add a small turbocharger or supercharger if you really need more torque/hp.


Posted By: shootist
Date Posted: Sep/26/2016 at 2:06pm
True Red, but it wouldn't be near as cool.

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Posted By: pipefactory
Date Posted: Sep/26/2016 at 3:47pm
Originally posted by shootist shootist wrote:

True Red, but it wouldn't be near as cool.


Ya that's the main reason. My single 360 pulled fine just had to be patient leaving the giant crater we live in. I could skoot along just fine at 65 mph pulling my Rambler in my trailer.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: mramc
Date Posted: Sep/26/2016 at 5:09pm
Ok The Land Speed records classes the AMC version of the Spirit of America would have run in were displacement limited , so no two AMC V-8 hooked together. One AMC V-8 with a GMC blower was what was planned. I did a lot of research the History of AMC Motor Sports for Bob McClure on a lot of this stuff. Also NHRA outlawed dual engine drag cars circa 1972. Yes there was a dual six cylinder engine dragster and then the team went to a six cylinder Gremlin . That is in the Performance American Style manual AMC put out in 1972. No one ran a dual engine car after 1971 except in the nostalgia drag races and then mostly for show.   LRDaum


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LRDaum


Posted By: pipefactory
Date Posted: Sep/27/2016 at 8:34am


Well here is the mock up.

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Face distorting torque
11.25 @ 116.7 mph


Posted By: amcenthusiast
Date Posted: Sep/27/2016 at 10:00am
My first thought was doubting the externally balanced nodular iron cranks strength to handle the twist -elasticity?

IMO, there will be an all new range of harmonic vibration frequencies by having both cranks connected -both cranks will be 'feeling' the other's resonate frequencies? which could translate into catastrophic destruction if/or there is a particular rpm where they conspire to resonate together?

but I think also most comments will be only chasing your leading thoughts to do this

At the very least I seriously think you need to consider dampening the harmonics of the second engine by using a bolt on type harmonic damper mounted to the coupling... I believe I could turn an adapter set up on my hd homemade benchtop lathe (see XRV8 Gremlin in 'member projects' section here on AMC Forum) -just to keep the stock harmonic damper ring for the second engine/just add it on to the joining adapter your friend made?

I agree with the idea of internally balancing both cranks to (help) insure durability; vibration is a destroyer of any engine

Considering there is a factory tolerance for imbalance on these 'fast build' engines, this raises a question in my mind for 'what if' the imbalance tolerance for both engines add together or 'what if' the imbalance tolerance could be used to offset the imbalance of the other -I think this could destroy or add to the smoothness of the engine?

The imbalance will send vibration waves throughout the rotating assemblies, finding 'dead ends' in each connecting rod, wrist pin and piston assembly? (each reciprocating unit will assume a whole new harmonic vibration frequency? -this calls for less brittle pistons, increased fatigue rated rods (used rods will already have built up fatigue) ...all the used pistons will rather instantaneously take on a unique wear pattern (from the unique resonate frequency of the two cranks) as soon as the engine is started? (pistons are malleable; they flex as an engine runs)

think of 'resonate frequencies' needing harmonic dampening like engines are vibrating like a bell -this problem was a common thing back when bells were a primary source of township communication -it seems there was much 'hit or miss' 'trial and error' with cast bells: the Liberty Bell is among the most well known examples?

tap on any engine block with a wrench; it will have a ring to it, this will be unique to every design; the ringing sound is vibration, the vibrations run through the metal itself (and those vibrations are heard by our ears as 'sound waves') -it may be argued that this is the better reason for using block filler in a race engine; to dampen 'harmonics'

(smiling) this idea tells me you might consider or take interest in AM's '56-'67 Rambler V8s because they all came with internally balanced forged steel components and were made by Gray Marine to use in reverse set ups for boats

no matter what engines you choose there should be much consideration for engine mounting -longitudinal rigidity and torsional rigidity, to protect the already stressed out cranks; they need to spin 'straight' to ensure bearing durability? Their combined straightness could be plotted out using a large concrete slab straight edges and plumb lines stretched to maximum length/distances (Great Pyramid used stars in the sky for geometrical reference points to ensure maximum geometrical alignment precision); the further away your reference points are the more they will contribute to precise geometry (of the mounting point locations around the engine etc) (like a larger (better for accuracy) or smaller degree wheel (less accurate) for 'degreeing in' a camshaft) -just ideas

if the cranks aren't 'straight' it could kill the project very quickly? -take out both endplay bearings and self destruct in a bad way to say the least? (endplay bearings could lose lubrication 'boundry layer' and that would cause nearly instant 'galling' to destroy those bearings? -combined crankshaft endplay needs technical solution? 

-just my two cents worth... this could grow into a lengthy discussion (pun intended)


Posted By: uncljohn
Date Posted: Sep/27/2016 at 11:55am
It just seems that there are a lot of mechanical problems in getting the crankshafts in line along with the blocks and then having things be stable and not move in relation to each other. Then getting the engines synced to run efficiently. There is a significant difference in getting 2 engines to work as one in a land speed vehicle or a tractor pull vs a motor home which won't be as rigid a platform to do those things in. 'Specially when both Ford and MOPAR have V10 engines available. But what the heck,it is a hobby anyway

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70 390 5spd Donohue
74 Hornet In restoration
76 Hornet, 5.7L Mercury Marine Power
80 Fuel Injected I6 Spirit
74 232 I-6, 4bbl, 270HL Isky Cam


Posted By: SC397
Date Posted: Sep/27/2016 at 12:44pm
Fun project!
It would be interesting to read Mr. Parkman's comments on harmonics and vibrations with this set up.
I was wondering if a Lovejoy type of coupler would be better or worse than a direct spline.
Keep it going, can't wait to hear it run! I wonder what the torque would end up at..


Posted By: SirDigger
Date Posted: Sep/27/2016 at 12:52pm
Fun project and why not?

But I´m with uncle john, when it comes to Engine Movement,
the solid connection between the 2 cranks will add a lot of load on the last/First Bearing when the Engines pull a bit diffrent.
.
May an Hardy disc between the 2 engines would cure a lot of "Maybe Problems"


 


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SirDigger&his german Friends are looking for Parts http://theamcforum.com/forum/the-german-amc-forum-ambassadorsirdigger-needs_topic83570.html
1970 Javelin SST 304
1970 Javelin SST 360


Posted By: 304-dude
Date Posted: Sep/27/2016 at 1:22pm
Why can't they be 180 degrees offset from each other, and run a igniton amp to split the output from one distributor to operate both engines. This way timing can be done fairly easily and harmonics will not amplify as the 180 degree offset harmonics will cancel each other out.

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71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker


Posted By: shootist
Date Posted: Sep/27/2016 at 2:18pm
I have to say this is one of the wildest things I believe I have ever seen anyone attempt with AMC motors. The engineering and thoughts that are going into this is quite impressive. I would have never attempted it myself just because I would have gone stroked 401 first due to the ease of build. I also think that if I had a plan to go two engines I would have probably gone the side by side route with a coupler transmission like many of the tractor pull guys do as I think reliability and ease of install would be so much better. However, there would be much more cost involved.

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Posted By: shootist
Date Posted: Sep/27/2016 at 2:21pm
Oh shoot. I just had an idea. if alignment and flex is such a concern could you not just use a universal joint like off of a big dump truck drive shaft? That would alleviate any bad mojo from body flex. Just spit balling it but works for a driveshaft and transmission.Could even use two like slip yolks joined with the u joint.


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Posted By: pipefactory
Date Posted: Sep/27/2016 at 4:15pm
Originally posted by amcenthusiast amcenthusiast wrote:


My first thought was doubting the externally balanced nodular iron cranks strength to handle the twist -elasticity?

IMO, there will be an all new range of harmonic vibration frequencies by having both cranks connected -both cranks will be 'feeling' the other's resonate frequencies? which could translate into catastrophic destruction if/or there is a particular rpm where they conspire to resonate together?

but I think also most comments will be only chasing your leading thoughts to do this

At the very least I seriously think you need to consider dampening the harmonics of the second engine by using a bolt on type harmonic damper mounted to the coupling... I believe I could turn an adapter set up on my hd homemade benchtop lathe (see XRV8 Gremlin in 'member projects' section here on AMC Forum) -just to keep the stock harmonic damper ring for the second engine/just add it on to the joining adapter your friend made?

I agree with the idea of internally balancing both cranks to (help) insure durability; vibration is a destroyer of any engine

Considering there is a factory tolerance for imbalance on these 'fast build' engines, this raises a question in my mind for 'what if' the imbalance tolerance for both engines add together or 'what if' the imbalance tolerance could be used to offset the imbalance of the other -I think this could destroy or add to the smoothness of the engine?

The imbalance will send vibration waves throughout the rotating assemblies, finding 'dead ends' in each connecting rod, wrist pin and piston assembly? (each reciprocating unit will assume a whole new harmonic vibration frequency? -this calls for less brittle pistons, increased fatigue rated rods (used rods will already have built up fatigue) ...all the used pistons will rather instantaneously take on a unique wear pattern (from the unique resonate frequency of the two cranks) as soon as the engine is started? (pistons are malleable; they flex as an engine runs)

think of 'resonate frequencies' needing harmonic dampening like engines are vibrating like a bell -this problem was a common thing back when bells were a primary source of township communication -it seems there was much 'hit or miss' 'trial and error' with cast bells: the Liberty Bell is among the most well known examples?

tap on any engine block with a wrench; it will have a ring to it, this will be unique to every design; the ringing sound is vibration, the vibrations run through the metal itself (and those vibrations are heard by our ears as 'sound waves') -it may be argued that this is the better reason for using block filler in a race engine; to dampen 'harmonics'

(smiling) this idea tells me you might consider or take interest in AM's '56-'67 Rambler V8s because they all came with internally balanced forged steel components and were made by Gray Marine to use in reverse set ups for boats

no matter what engines you choose there should be much consideration for engine mounting -longitudinal rigidity and torsional rigidity, to protect the already stressed out cranks; they need to spin 'straight' to ensure bearing durability? Their combined straightness could be plotted out using a large concrete slab straight edges and plumb lines stretched to maximum length/distances (Great Pyramid used stars in the sky for geometrical reference points to ensure maximum geometrical alignment precision); the further away your reference points are the more they will contribute to precise geometry (of the mounting point locations around the engine etc) (like a larger (better for accuracy) or smaller degree wheel (less accurate) for 'degreeing in' a camshaft) -just ideas

if the cranks aren't 'straight' it could kill the project very quickly? -take out both endplay bearings and self destruct in a bad way to say the least? (endplay bearings could lose lubrication 'boundry layer' and that would cause nearly instant 'galling' to destroy those bearings? -combined crankshaft endplay needs technical solution? 

-just my two cents worth... this could grow into a lengthy discussion (pun intended)



I haven't decided on the balancing of the permanent 2 engines yet but will consider your advice. The mock up blocks will be locked together 1st with a 3" DOM tube through all the mains with no bearings then I'm bolting them together with a modified bell housing. They should be lined up nicely that way. The thing that concerns me is the strength of the rear motors cast flange as the front motor will make about 360 foot pounds of torque then the rear flange would transfer about 720 to the torque converter. I was thinking of destroking a 390 crank I have.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: shootist
Date Posted: Sep/27/2016 at 4:18pm
I think the rear engine's crank would have a much greater chance of survival if you use the forged 390 crank and detroke it like you mentioned.

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Posted By: scott
Date Posted: Sep/27/2016 at 4:25pm
The problem I see is that all the power of the front engine is going to be transmitted to the rear engine thru the harmonic balancer. Looks like 4) 3/8" bolts on the rear engine coupling to balancer, when the coupling on the front engine crank is 6) 1/2 or 7/16" bolts. Then, the balancer is kept from spinning at the crank on the rear engine by a press fit & a key. That setup is made to drive the engine accesories, maybe a maximum of 10-20 HP ever goes thru it. You're asking it to transmit hundreds of HP. I don't see it lasting more than a minute or two before either the key shears or the coupler to balancer bolts shear. 


Posted By: pipefactory
Date Posted: Sep/27/2016 at 4:38pm
Originally posted by scott scott wrote:

The problem I see is that all the power of the front engine is going to be transmitted to the rear engine thru the harmonic balancer. Looks like 4) 3/8" bolts on the rear engine coupling to balancer, when the coupling on the front engine crank is 6) 1/2 or 7/16" bolts. Then, the balancer is kept from spinning at the crank on the rear engine by a press fit & a key. That setup is made to drive the engine accesories, maybe a maximum of 10-20 HP ever goes thru it. You're asking it to transmit hundreds of HP. I don't see it lasting more than a minute or two before either the key shears or the coupler to balancer bolts shear. 


People do this with SBC's and they have 3 5/16" bolts also the AMC balancer has a pretty tight press fit. I would be a problem if the rear motor wasn't moving but they will be both moving at the same RPM.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: pipefactory
Date Posted: Sep/27/2016 at 4:48pm
Thanks for all the comments and advice and that includes the nay sayers. I'm going to do this and I will iron out all the problems. I remember a few years ago when I posted my AMC 360 swap into my motorhome, a lot of people here and some of my friends that live around here said my 360 wouldn't have the power to pull the thing let alone tow my race car. This is probably the 4th year and it's been a real trooper. Also once I put a KZ 550 Kawasaki motor in a 91 Toyota Tercel same thing happened. My step son is still driving it. I hope everyone doesn't think this is coming off sarcastic because it's not ment to be.
And keep them coming I love it!
Don't you just love a challenge though!!

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Face distorting torque
11.25 @ 116.7 mph


Posted By: 304-dude
Date Posted: Sep/27/2016 at 4:55pm
As for questioning a balancer with strong coupling. Instead, I'd internally balance the engines and directly couple them. As to couple them, I would have the snout double keyed and machine the balancer center with the ring removed to mount to the crank flange of the front engine.

-------------
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker


Posted By: Hurst390
Date Posted: Sep/27/2016 at 5:34pm
In my experience the bert shaft and couplings your using have a fair amount of slop in the splines. I would definitely do a precision alignment though.
I also agree with Scott and would be worried about (even though they are both running) the keyway on the rear engine balancer. I would look into using an sfi balancer with a steel hub and drill for a roll/dowel pin through the hub and crank snout. I think you could do that with an ati because the shell is farther away from the timing cover and allow driving in the pin. That way if you were to lose the rear engine you could pull the plugs and get home on the front engine :)
The internal method and a direct coupling makes the most sense but more expensive .
Cool idea for sure.


-------------
SC/Hurst Rambler

11.62 120

100% Street Legal


Posted By: farna
Date Posted: Sep/27/2016 at 6:31pm
The external balance of the engine won't be a problem -- you just have to run the flexplate on the front engine so it's balanced. As others have commented -- the crankshaft isn't a problem unless the rear engine dies and front keeps running. I don't think it will be an issue even then -- you'll be dragging eight cylinders, which should quickly choke down the front engine. At least you'll know something is up!

I suggest an electronic ignition system, something like a Megajolt using a trigger wheel instead of a dizzy. You can program it to fire whenever you want, and can fire two coils at once. Going to individual coils for each cylinder would be nice. You can get motorcycle coils with two leads that fire at the same time. They use a wasted spark system, a spark plug firing on the exhaust stroke doesn't take much energy.

It seems to me the the absolute easiest way to work this is just to fire both engines simultaneously using the same firing order rather than try to make it run like a true V16. It will fir evenly and run as smooth as a single V8 would that way and be simple to implement. Would still give the same power as firing as a V16.


-------------
Frank Swygert


Posted By: shootist
Date Posted: Sep/27/2016 at 6:44pm
That was my thought farna just use a single dizzy as more of a trigger for the on the plug coil packs. you would still need to drive the oil pump on the rear motor but that would be it. I had not thought out all of the details of course but it would at least get your motor firing in time with each other and reduce the harmonics of out of synch firing.

-------------


Posted By: 53w
Date Posted: Sep/27/2016 at 7:03pm
As already pointed out the 2nd engine in line crank will see up to double the load transmitted through the crank to PTO end. Twice the twisting cycles, possibly loaded in both directions at times.

The harmonic damper to transmit all the power from front engine to the second engine crank. I really do not see this holding at all.

There is mathematical formulas for interference fit holding power. I would first consult the math behind the project before moving forward. You may have to make a custom damper to get the right interference fit, but then how do you get it on and off with such a tight fit.

Double keys maybe hold? There is also engineering tables for amount holding power of a key on a shaft also.

A splined shaft to link two engines together, that joint is going to take a extreme pounding. Due to it is a short length of shaft from engine to engine and nothing to absorb the shock loads. It will wipe the splined set up out fast and it also will work fatigue and fail.

The automotive transmission's splined output shaft uses the tires as the shock absorber from the piston fire shock loads, so it never gets gets the shock loads hard.   

Even on simple boat motors the lower unit drive shafts are designed to absorb by twisting at each piston fire and the rubber hubs in the prop also absorb the piston fire shock loads away from the drive-train.

To get reliability and drive it long ways from home and back it will not work. Get it down the 1/4 mile a couple of times yes it will move.


Posted By: Boris Badanov
Date Posted: Sep/27/2016 at 7:27pm
I think I would take the time to hobb a spline on the front of the rear crank.
But I have that option.

I do believe the key will shear.



-------------
Gremlin Dreams


Posted By: 53w
Date Posted: Sep/27/2016 at 7:45pm
Some type of spline shaft to flexplate coupled to second flexplate back to spline would aid in slight alignment flaws and maybe absorb some shock loading. But even then ??????


Posted By: ghinmi
Date Posted: Sep/27/2016 at 7:51pm
I have seen the single keyway shear a bunch of times just trying to drive a supercharger.  Double key with an aftermarket balancer if you want it to have a chance at life.

-------------
1983 Cherokee - Turbo Hemi autocross/road race


Posted By: Boris Badanov
Date Posted: Sep/28/2016 at 9:50pm
I seem to remember the Kenz and Leslie twin flatties
were welded to the coupling.

This may be the only cost effective option.

-------------
Gremlin Dreams


Posted By: ghinmi
Date Posted: Sep/29/2016 at 1:34am
A little late in the game, but what about a flex coupler like they use to connect the driveshaft to trans in the independent rear suspension muscle cars?  Think new Challenger, Camaro, etc.  They'll handle the speeds and torque no problem and isolate the engine harmonics.

-------------
1983 Cherokee - Turbo Hemi autocross/road race


Posted By: farna
Date Posted: Sep/29/2016 at 7:59am
You might need an industrial coupler. Something like this -- the biggest Grainger lists.

https://www.grainger.com/product/BOSTON-GEAR-FC45-2-1-8-Steel-Shaft-Coupler-2L063?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/2L028_AS01?$smthumb$

Of course you'd need TWO $500 bubs plus a $200 spider to go between them. That hub is not the correct size, so all may be cheaper. I just picked the biggest one. Would need to be a steel hub, not sintered iron, I would think. Couldn't find torque ratings on the hubs, only the inserts.


-------------
Frank Swygert


Posted By: pipefactory
Date Posted: Sep/29/2016 at 8:12am
Im thinking of drilling a 1/4" hole in the balancers washer to use as a alignment hole to drill 2 holes evenly spaced with the existing keyway between the shaft and the balancer and drive in 2 rods to use as keyways and locktight the balancer. Back in the late 60's the twin engine dragsters used two sprockets side by side and wrapped the with double row chain. also the put 2 extra keys on the balancer.
The way I'm setting this up is going to be aligned as straight as if it were one shaft. also the 10 splined input shaft and couplers I'm using have a small amount of play. The shaft is the same a the T10 4 speed so it should be strong enough.
and remember, the front motor isn't going to take of first then spin the rear. They'll act like one motor.
Yesterday I cut down my bell housing now just waiting on the aluminum.


-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: pipefactory
Date Posted: Sep/29/2016 at 8:15am
Check out this thread.
http://www.jalopyjournal.com/forum/threads/twin-engine-coupling-how-do-you-get-two-v8s-in-line.624584/

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: Greyhounds_AMX
Date Posted: Sep/29/2016 at 1:12pm

Yannick Sire's car uses an IRS coupler from a GTO:



http://www.hotrod.com/articles/hrdp-0909-custom-speed-buggy/" rel="nofollow - http://www.hotrod.com/articles/hrdp-0909-custom-speed-buggy/


There also a video of the coupler setup on Youtube if you go hunting for it.





-------------
Chris ("Mojo")
1968 AMX 390


Posted By: 304-dude
Date Posted: Sep/29/2016 at 1:59pm
Originally posted by Greyhounds_AMX Greyhounds_AMX wrote:

Yannick Sire's car uses an IRS coupler from a GTO:



http://www.hotrod.com/articles/hrdp-0909-custom-speed-buggy/" rel="nofollow - http://www.hotrod.com/articles/hrdp-0909-custom-speed-buggy/

There also a video of the coupler setup on Youtube if you go hunting for it.


Looks like a steering shaft flex joint out of a Vauxhall to me. Australian cars from GM are always upgraded to meet Australian demands. HEHEHEHEHEHE!

-------------
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker


Posted By: Boris Badanov
Date Posted: Sep/29/2016 at 8:57pm
Still need to beat the problem of the key taking all the load.

-------------
Gremlin Dreams


Posted By: 304-dude
Date Posted: Sep/29/2016 at 9:04pm
Originally posted by Boris Badanov Boris Badanov wrote:

Still need to beat the problem of the key taking all the load.


Yeah, I mentioned double keying... but we are talking 300hp per engine. Maybe welding up the snout and machining grooves for a slip yoke fit. Will allow for variances between load ups transfering shocks between engines.


-------------
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker


Posted By: Boris Badanov
Date Posted: Sep/30/2016 at 6:08am
Hobbing a timed spline is best but cost prohibitive.

If I had to do this I would use a solid balancer
and weld the inside to the crank.

There is really no easy way out.

-------------
Gremlin Dreams


Posted By: uncljohn
Date Posted: Sep/30/2016 at 9:40am
Getting two crank shafts to act as one by welding them together certainly raises the question of getting the alignment dead nuts on! And if that has to be true, there has been no discussion on getting the blocks in alignment so that they serve as a fixture to hold the crank shaft in place. It would seem to me that doing that gets a bit sporty as an exercise too.
I have done that with fractional HP motors successfully using a flexible coupler, but I am not aware of a flexible coupler that can be used and still act as an external balancing medium the AMC engine as configured requires.
Getting two engines to act as one it would seem to me that common denominator would be to get the intake manifold to be jointly shared by the two blocks which probably can be more easily done by using a port fuel injection system or just using one engine as an input signal reference to drive both engines with.
Just thinking about this

-------------
70 390 5spd Donohue
74 Hornet In restoration
76 Hornet, 5.7L Mercury Marine Power
80 Fuel Injected I6 Spirit
74 232 I-6, 4bbl, 270HL Isky Cam


Posted By: 304-dude
Date Posted: Sep/30/2016 at 10:07am
If somebody by chance does not over think the situation, I am sure they will get it to work. Just long term durability will be the concern, unless they tend to build things loaded for bear. Then it would be a matter of how much resources in material and money one will throw at it.

If building like my cousine... the need to just have fun with it, is more important than how long it lasts. Yep, not many of his builds were long term but boy does he have a long list of odd and fun builds that did what he intended and lived longer than expected after a few trials and errors. Some were just too wild to enjoy at full potential. Like stuffing a big bike motor in a Yamaha quad runner back in 89. Nothing scared him more than that, as all it wanted to do is lay back and flip, with his big arse leaning over the front as far as he could.

Then there was his jetski clocked at 80Mph on the river. He blew It up after so many fun runs. He admitted, the pistons melted from constant the high rpms.

-------------
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker


Posted By: farna
Date Posted: Sep/30/2016 at 10:34am
What you really need is a torque converter between the engines. Then time them together for minimal "interference". Would be tough and take up a lot of room though. The IRS joint is much tougher than a steering joint, but bear in mind that it only take HALF the engine power since the other axle is getting half. Not sure how long it would hold up. Since it's not a drag car and won't be getting shocked hard very often (if at all) it should be fine though. Remember the application -- two near stock engines.

I have an article in an old handy man type book from the early 60s that has an interesting way to connect two engines. They used two transmissions and two differentials -- on the same axle. I would have to look up the article but I think there was a shaft linking the two differentials. Just to be clear, they had ONE rear axle with two differentials (naturally they were "one leggers" or limited slip), with two engines and trannys side by side. That took ALL the timing issues and such out of the equation. You'd want two engines of the same power, but the auto trannys did a lot of buffering. IIRC it would even run on one engine for moving around the track and on/off trailer. .


-------------
Frank Swygert


Posted By: 304-dude
Date Posted: Sep/30/2016 at 11:08am
Ha, Farna, I was joking about the steering joint. At one time there was once a long standing play on words about Aussie comparisons. If saying average hunting sized knife, it be a pocket knife in Australia.

-------------
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker


Posted By: pipefactory
Date Posted: Sep/30/2016 at 4:04pm
After I'm done mocking everything up I'm going to put it all together with 2 360s that have over 100000 miles on them then I'm going to put them to a test in my garage on a stand. I figure if I run them unequally with separate throttles that should show me how strong the balancer and coupler are. Then I thought I'd hook up an old 727 and lock the tail shaft and find the week link. Sound too crazy?


-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: 304-dude
Date Posted: Sep/30/2016 at 4:22pm
I'd drill and tap the balancer holes a size up, either metric or standard.

The only way to tell if you are going to break balancer bolts is to bump full throttle harshly a few times with one engine while the other is idling or off. No trannie needed. Should be interesting on how good of a puller one engine is when other is seriously lagging.

I figure some serious spontaneous twists will show for weak fasteners or balancer. Just be careful for a prompt shut down when needed.

-------------
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker


Posted By: Boris Badanov
Date Posted: Sep/30/2016 at 7:12pm
Save yourself the trouble of melted steel and ruined cranks.

Do a bit off research. Kenz and Leslie did it with flatties.

Tom Ivo did it with nail heads.

There's been many others.

I love your idea and I believe it will work well!

But you need to get those motors joined in a secure manner....


-------------
Gremlin Dreams


Posted By: pipefactory
Date Posted: Sep/30/2016 at 7:35pm
They'll be straight inline and secure. By the way Boris do you have a shop called motors by Boris? Been meaning to ask you that.


-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: ghinmi
Date Posted: Sep/30/2016 at 8:05pm
http://www.dragzine.com/news/flashback-friday-tommy-stringfields-1128ci-triple-engine-nova/

-------------
1983 Cherokee - Turbo Hemi autocross/road race


Posted By: Greyhounds_AMX
Date Posted: Sep/30/2016 at 10:54pm
pipefactory,

Is Phil Hanson still up in that neck of the woods? When I was in high school I used to get AMC parts from him, he was up the North Shore a bit toward Two Harbors.

For the longest time he was trying to give me a 401 for my Jav instead of the hopped up 258 I had, and I think he was trying to get me to date one of his daughters as well but I was too thick to figure out what he was hinting at back then.


-------------
Chris ("Mojo")
1968 AMX 390


Posted By: pipefactory
Date Posted: Oct/01/2016 at 6:57am
Originally posted by Greyhounds_AMX Greyhounds_AMX wrote:

pipefactory,

Is Phil Hanson still up in that neck of the woods? When I was in high school I used to get AMC parts from him, he was up the North Shore a bit toward Two Harbors.

For the longest time he was trying to give me a 401 for my Jav instead of the hopped up 258 I had, and I think he was trying to get me to date one of his daughters as well but I was too thick to figure out what he was hinting at back then.
ya he is. He stops in at my Finnbilly garage at least one a week to see what kind of trouble I'm making for myself.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: pipefactory
Date Posted: Oct/08/2016 at 9:16am
Hi everyone. Here is the test engines I'm going to play with this winter. Should be running later today.
My only problem was the engines will be either 12 degrees or 52 degrees apart.
The cranks alignments should be spot on


-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: moondog
Date Posted: Oct/10/2016 at 8:12am
Hey Pipe Factory, Moondog chiming in.  Will be at your garage Tuesday to here this thing run, can't wait!  I learned my lesson when he put a Suzuki motorcycle engine in a Corolla that you don't tell him it can't be done.


Posted By: pipefactory
Date Posted: Oct/10/2016 at 8:44am
Hey Moon Dog looking forward to Tuesday also. I've been romping on the throttle already and it sounds cool. I managed to get them to 45 degrees apart.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: shootist
Date Posted: Oct/10/2016 at 5:52pm
Hey pipe, I want to test moondog's theory. You absolutely cannot under any circumstance buy me a jerico straightdrive, quicktime bellhousing, hydraulic clutch with pedal assembly, EPAS system or any other cool go fast object for my car.

Anyway, that is looking really cool. Interested in seeing this thing run.


-------------


Posted By: 304-dude
Date Posted: Oct/10/2016 at 5:59pm
Originally posted by shootist shootist wrote:

Hey pipe, I want to test moondog's theory. You absolutely cannot under any circumstance buy me a jerico straightdrive, quicktime bellhousing, hydraulic clutch with pedal assembly, EPAS system or any other cool go fast object for my car.


Anyway, that is looking really cool. Interested in seeing this thing run.


Sound a bit like me in an odd way... No frills to catch an eye or two. But it is more or less keeping it simple and straight forward. Though if I wanted a all out racer setup and had the means, a 65 convert would be my ticket to go crazy, even if I must cut and weld a whole front end to allow all the stuff to fit.

-------------
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker


Posted By: 304-dude
Date Posted: Oct/10/2016 at 6:09pm
After seeing the two engines mated, a few thoughts popped up... One, there is enough room for turbos to be fitted between the engines. Two, graft two air gaps together using long runners and a mini tunnel as a bridge, with two 850s centered between the engines. The later is for looks, as I dont think anyone has done an odd thing like that.

-------------
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker


Posted By: Red20
Date Posted: Oct/10/2016 at 6:13pm
This'll be the first lakes racer you can sleep in after a day of racing.

-------------
1969 Javelin SST "Screamin' Banana" - 16k original miles, warm 360, TH-350, Model 20 TracLok, DAILY DRIVER


Posted By: shootist
Date Posted: Oct/10/2016 at 6:37pm
LOL Too Funny Red. Now for a bit of comic relief.






-------------


Posted By: pipefactory
Date Posted: Oct/11/2016 at 6:10am
Originally posted by shootist shootist wrote:

Hey pipe, I want to test moondog's theory. You absolutely cannot under any circumstance buy me a jerico straightdrive, quicktime bellhousing, hydraulic clutch with pedal assembly, EPAS system or any other cool go fast object for my car.


Anyway, that is looking really cool. Interested in seeing this thing run.
it's 5am don't make me laugh so hard this early.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: pipefactory
Date Posted: Oct/11/2016 at 6:15am
Moondog wanted to race me with his RV but he has 2 more cylinders than me so I had to stack the deck in my favor.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: shootist
Date Posted: Oct/11/2016 at 9:47am
After this you will have him covered. :)

If you look closely at the black RV that thing has what appears to be a yellow painted Kirkey seat or similar race seat with the head restraints. It is actually kind of cool in a "why in the heck would you do that sort of way."


-------------


Posted By: pipefactory
Date Posted: Apr/19/2017 at 8:24am
OK here's the rear motor was going to put the heads on the front one but I couldn't find my head bolts.
Over the winter I did some testing on the used ones, The front runs at 150 and the rear runs at 180. Also I locked the tail shaft on a 727 and put it in 1st gear and managed to easily stall the stock converter to 2800 RPM's.
I want to get to the dyno by the end of the month. After breaking the motors in, I'm just tuning it for max torque that's it.
Also we have a dyno pull board going down at the garage for max torque.
Anyone want to make some guesses on max torque including catastrophic failures.

-------------
Face distorting torque
11.25 @ 116.7 mph


Posted By: Boris Badanov
Date Posted: Apr/19/2017 at 12:19pm
Awesome piece of work!
I hope the coupling survives the first start/run.


-------------
Gremlin Dreams


Posted By: shootist
Date Posted: Apr/19/2017 at 3:18pm
I am assuming this guesstimation is for max torque at the crank? If so, I am going to throw out 600 @ 3000. I am not putting the catastrophic failure vibe out there. I am wishing you success. However, please video it so we can see it in action be that flawless operation or self-destruction.


-------------


Posted By: 304-dude
Date Posted: Apr/19/2017 at 3:34pm
Let's see... 600 ft lbs of torque at 3000 RPM is doable though I don't think the crank limit is a problem at that RPM. I think 700 ft lbs can be done more around 4K.

The coupling would be my concern as it is untested and new ground.

I assume you are using arp studs on the mains, anywho. Since you are doing a lot of work to make this happen.



-------------
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker


Posted By: Boris Badanov
Date Posted: Apr/19/2017 at 7:55pm
Harmonics on a long crank like that have to be pretty severe.
And there is the coupling....


-------------
Gremlin Dreams


Posted By: n2ojoe
Date Posted: Apr/20/2017 at 12:48am
Although I wish you the best of luck with your efforts, I'll place my bet on the weakest link being the crank damper keyway on the second engine and not the actual coupler. Very cool project!


Posted By: Boris Badanov
Date Posted: Apr/20/2017 at 6:09am
I will be (pleasantly) surprised if that key way lasts
through the first start let alone under load.

-------------
Gremlin Dreams


Posted By: 304-dude
Date Posted: Apr/20/2017 at 6:26am
Originally posted by Boris Badanov Boris Badanov wrote:

I will be (pleasantly) surprised if that key way lasts
through the first start let alone under load.


Maybe I read through too fast... wasn't the plan to add extra keyways. One is not enough. Two is doubley better, but in thinking it through 4 would be my thoughts.



-------------
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker


Posted By: farna
Date Posted: Apr/20/2017 at 6:43am
Yeah, I would think the keyways will be the weak link. Splined like a trans output would be best, but lots of work. Some sort of cushioning connection would be good too. Wish I knew what that guy who used to drag two AMC sixes connected like that used! But one quick all-out pass is a lot different than being reliable on he street under varying load conditions...  A low stall torque converter between them would be nice, but there would have to be a way to pump oil through it for cooling. Hmm... an old M-35 air cooled converter?


-------------
Frank Swygert


Posted By: shootist
Date Posted: Apr/20/2017 at 8:22am
I haven't really looked too closely at how the coupler and the rear engine tie together but it looked like it was splined on the rear motor. If not, I would have to agree the keyway is the most likely point of failure. If they are tied together where that isn't the weak point the next likely point of failure is the rear engines crank but that would be under load.


-------------


Posted By: farna
Date Posted: Apr/21/2017 at 6:29am
As long as both engines are in sync/tune with each other, I don't think there will be much stress at all. But if one gets a fouled spark plug or a plug wire fails, that throws them out of sync and you have one engine helping the other along, putting stress on the coupling. I know some of you guys are concerned about added stress on the rear engine crank, but I'm not so sure that's an issue. Same engine used in a big heavy truck would have as much stress. VAM used the AMC six in two ton trucks -- heavier trans than even Jeep used behind that engine, but same crank as used in cars. If the engines get out of sync, say the rear engine loses a cylinder, that will put added stress on the rear crank, maybe enough to cause an issue, but the connection between the two should be the weak link.


-------------
Frank Swygert


Posted By: Boris Badanov
Date Posted: Apr/21/2017 at 7:35am
IMO the crank is not a weak link at all.
But that key is.

Even under motorcycle style loads
I have seen similar press or tapered fit
keyed Harley based cranks fail at the out put shaft.

And those whom press fit the drive side shaft
use a typical press of .009"

That's a whole lot more than AMC uses on the balancer.




-------------
Gremlin Dreams


Posted By: shootist
Date Posted: Apr/21/2017 at 9:14am
I can see the point of the crank not being the weak point but let's say for a moment that the two motors are fused together perfectly and that point of failure is addressed. What is your next possible point of failure? I would believe that to be the rear crank sine technically you are introducing a higher twisting factor that is likely to exceed what the crank was engineered for. If we were talking about a forged crank I don't think it would be any concern at all. However, remember we are using stock cast cranks only designed to hanlde a certain level of TQ. Super cool project. I believe that provided there is no shock impact to the crank (like wheel hop would introduce) there shouldn't be an issue though.

I would ask though. If not the crank as the second most likely point of failure what else would you guys see as the next possible problem?


-------------


Posted By: 70amxpaul
Date Posted: Apr/21/2017 at 4:19pm
Yes, back in the day, one of the AMC performance guides has photo of dragster with two 232 ci inline engines set up .

-------------
1970 red AMX 390 4speed AM FM rally PAC go PAC tilt rim blow black leather service block 60 over Canton pan Ross piston Indy intake Eddie heads Crane roller cam kit Ford 9 posi roll bar 65000 miles


Posted By: farna
Date Posted: Apr/21/2017 at 6:01pm
I would see one of the cranks being the next weak point after the connection between the two, but not for the reasons you give. Theoretically there is no more torque going through the rear crank than the front, as long as both engines are working together. Think of it as a straight eight crank, or even a straight six. There is no more stress on the first four cylinder (or three) as the rear cylinders. The long straight eight cranks would break when subjected to high power, but simply because they were long and all but the last iterations only had five main bearings, not nine (IIRC the mid 50s Buicks had nine mains...), and they just weren't designed for high rpm and power. From Wikipedia:

"A straight-eight can be timed for https://en.wikipedia.org/wiki/Engine_balance#Inherent_mechanical_balance" rel="nofollow - inherent primary and secondary balance , with no unbalanced primary or secondary forces or moments. However, https://en.wikipedia.org/wiki/Crankshaft" rel="nofollow - crankshaft https://en.wikipedia.org/wiki/Torsional_vibration" rel="nofollow - torsional vibration , present to some degree in all engines, is sufficient to require the use of a https://en.wikipedia.org/wiki/Harmonic_damper" rel="nofollow - harmonic damper at the accessory end of the crankshaft. Without such damping, https://en.wikipedia.org/wiki/Fatigue_%28material%29" rel="nofollow - fatigue cracking near the rear https://en.wikipedia.org/wiki/Main_bearing" rel="nofollow - main bearing https://en.wikipedia.org/wiki/Journal_%28mechanical_device%29" rel="nofollow - journal may occur, leading to engine failure.

Although an https://en.wikipedia.org/wiki/Inline-six_engine" rel="nofollow - inline six -cylinder engine can also be timed for inherent primary and secondary balance, a straight-eight develops more power strokes per revolution and, as a result, will run more smoothly under load than an inline six. Also, due to the even number of power strokes per revolution, a straight-eight does not produce unpleasant odd-order harmonic vibration in the vehicle's https://en.wikipedia.org/wiki/Driveline" rel="nofollow - driveline at low engine speeds.

The smooth running characteristics of the straight-eight made it popular in luxury and racing cars of the past. However, the engine's length demanded the use of a long engine compartment, making the basic design unacceptable in modern vehicles. Also, due to the length of the engine, torsional vibration in both crankshaft and https://en.wikipedia.org/wiki/Camshaft" rel="nofollow - camshaft can adversely affect reliability and performance at high speeds."

Since the coupling theoretically makes this one long crankshaft, the same results should be seen, so if there is a crank failure it should be at the rear bearing as well. That's assuming the hub/keys hold up. At least you don't have to worry about a long camshaft! I would think that timing or fuel issues can cause the engines to get out of sync, which would cause additional torsional stresses, and the crank will break at a weak point... usually at the rear main because that's where the trans hub is, the point of most stress (at least when driving a vehicle). Might be different on a stand, but I doubt it -- you still have the extra weight of the torque converter or flywheel.

Here is something interesting though...
"The (Mercedes-Benz) 300SLR was the final development of the Alfa Romeo (straight eight) design of the early 1930s as not only the camshaft, but now also the gearbox was driven from the engine's centre. Engineers calculated that torsional stresses would be too high if they took power from the end of the long crankshaft, so they put a central gear train in the middle (which also ran the dual camshafts, dual magnetos, and other accessories) and ran a drive shaft to the clutch housing at the rear."

This was a 3.0L engine... 310 hp @ 7400 rpm, 235 ft/lb @ 5950 rpm. Little thing... only 183 cubic inches!! In a very light car though, 1986 # dry. The torsional stresses were from the high rpm though, nothing the 720 inch monster should experience.


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Frank Swygert


Posted By: Boris Badanov
Date Posted: Apr/21/2017 at 6:59pm
Torsional vibration has plagued multi cylinder engines for the last century and a half.

Some early engines had certain RPMs that you could only run at passing by.
Stay there and it will break a crank.

The US "Liberty" was a good example of a bad engine
in this respect, although there were others that were worse.

Building a V16 AMC is certainly in charted waters.
I hope it runs great and is perfectly reliable!

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Gremlin Dreams


Posted By: shootist
Date Posted: Apr/21/2017 at 7:39pm
Ok so failure in this configuration are likely to be more from the harmonics and less of a torsional issue. I am still not so sure that you wouldn't ultimately shear the cast crank at the rear main journal or the front main journal under stress but at a lower RPM I do believe the risk is greatly reduced though the harmonics issue still would exist.

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