Print Page | Close Window

Header Hack

Printed From: TheAMCForum.com
Category: The Garage
Forum Name: AMC V8 Engine Repair and Modifications
Forum Description: AMC-made V8 engine mechanical, ignition and fuel from basic repair to high-perf modifications
URL: https://theamcforum.com/forum/forum_posts.asp?TID=80213
Printed Date: Mar/28/2024 at 5:01am
Software Version: Web Wiz Forums 12.03 - http://www.webwizforums.com


Topic: Header Hack
Posted By: Greyhounds_AMX
Subject: Header Hack
Date Posted: Jun/10/2016 at 12:53pm
I’ve always wanted headers on my '68 AMX but didn’t want the associated leaking gaskets, leaking flanges, bottoming out, etc. It seems some brands have better flanges than others so gaskets may not be an issue, but collector flanges still are a trouble spot. And my car sits LOW, so I’m going to bottom out any stock headers.

 

I decided to re-shape a set of headers to form fit my car using an old set I had laying around. I got these at a swap meet as part of a $60 package deal, and the other parts (including a Machine manifold) were what I was after, so IMO they were free. I tried to sell them at NAMDRA and had no takers at $80, so they’ve been sitting on the shelf for 10+ years now. They were in very good condition and ceramic coated, so I had that blasted off since I expected to be doing a bunch of welding on them.

 

After test fitting the driver’s side it was apparent that the forward bends near the oil pan needed to move up about 1.5”, and the collector needed to come up about 2.5” and move out toward the rocker a few inches to give some clearance to the clutch release arm. You have to look past the hanging exhaust pipe to see the relationship between the header collector and the frame - it’s angled down quite a bit.

 

I mounted a spare cylinder head on my welding cart at the same angle as the heads are on the block, and arranged some wood to indicate the original elbow and collector position. Then I sketched the required positions based on how far up I wanted to move, and started trimming the tubes accordingly.

 

 

There was a problem though, in that the pipes hit the Jeep slave cylinder before I could get them up where I wanted them. I moved everything up intil it pretty much contacted the slave, but the collector was still hanging too low.

 

 
 
 
The solution was to move to a “pull-type” slave from Wilwood instead of the stock push type slave cyinder. There are a number of pull-type slaves available from Wilwood, CNC, Howe, Coleman, and Speedway. Of them, the Wilwood has the longest travel and has the same bore size as the stock Jeep slave that I’m replacing. It’s $82 at Jegs/Summit. Here’s an example of a pull-type on a T5. I don’t have mine mounted yet.

 

 

With the slave out of the way I could pull the collector up nice and tight to the floor. The two center pipes simply got shorter and got a slight angle to roll the collector out toward the side of the car, and the font pipe was reconnected using the original elbow trimmed down to fit. The rearmost pipe was heated with a torch and stretched to meet up before welding. Now the lower elbows are about level with the crossmember, and the collector is as close to the floor as practical.

 

 

On the passenger side it only needed to move up (about 1.5" up at the elbows and about 2" up at the end of the collector), but it was obvious that the stock starter would prevent moving the pipes upward the same amount as the driver side. I opted for an Alterstart reman mini starter because it has a bunch of mounting orientations and the motor is mounted up high, away from the header heat. And it’s cheap, like me.  LOL

 

More to come...

 

 



-------------
1968 AMX 390 w/T5



Replies:
Posted By: THE MENACE
Date Posted: Jun/10/2016 at 1:33pm
If you want to never have to replace the collector gaskets you can use something like this!


It's an OE style conical seal and heavy duty flanges. It not only won't blow out like the flat gaskets do, but also allows for some engine movement without putting unwanted stress on the header tubing which can eventually cause tube cracking.

Dennis

-------------
Former Owner of:
The Craig Breedlove "AERO AMX"

Still Owner:
SS/AMX #9 replica (THE BIG MENACE)
70 AMX 416, EFI, Nash 5 speed   
70 Javelin 401, 727 (Wife's)
72 Gremlin Autocross Project.


Posted By: White70JavelinSST
Date Posted: Jun/10/2016 at 1:49pm
X 2 on Dennis' suggestion.

I'm guessing the collector is 3" on your headers. There's a myriad number of "ball and socket" or "ball flange" collector kits available. Jeg's, Summit, lots of places to buy from too. There are two bolt flange and three bolt flange varieties.

Post up more photos, I'm real curious on this one as I've got a set of Hedmans that are NOS, but the welds at the header flanges are real crappy, the flange itself is too thin to resist warping and the collector flanges are not ball and socket type. I bought a set of thick header flanges and a 3 inch ball and socket collector kit to redo the headers exactly as you are.

BTW, nice work, very pretty welds.


-------------
70 Javelin SST, second owner, purchased 1972


Posted By: motorhead_1
Date Posted: Jun/10/2016 at 4:57pm
nice work! looks tight, were you able to weld 360 around the header tubes?

-------------
69 SC/Rambler tribute 401/th400, 68 Rebel SST LSA, 66 F100 460/c6, 88 Merkur Xr4Ti, 71 Jaguar XJ6 LS1, 08 Supercharged Tundra


Posted By: jrsjav
Date Posted: Jun/11/2016 at 10:49am
Remflex header gaskets are the real deal, I really like mine.






Life's to short to be stock!


Posted By: Greyhounds_AMX
Date Posted: Jun/11/2016 at 4:05pm
Thanks guys. It's been a fun project so far.

It was kind of tough to weld between the two center pipes, but I used two rear axle leaf spring wedge plates to open the gap between the two pipes slightly and that helped.

I considered using the ball and socket setup at the collector, but heard a few problems with them. Next thought was the setup like Dennis has except with spring loaded bolts, as I see that on lots of Imports and it seems to work well. But it's typically only a single pipe so rotation around the joint is possible, but when you add a second pipe to the mix like in a V8 application there wouldn't be rotation, but translation.

With that in mind I've decided to us a flex joint on each pipe. The flex joints alone should relieve enough stress to let the gaskets live longer, but I'm getting rid of them as well. The plan is to weld reducers right to the collectors, follow that with the flex pipe, and then join that to the rest of the system with a stainless band clamp.




-------------
1968 AMX 390 w/T5


Posted By: 304-dude
Date Posted: Jun/11/2016 at 5:09pm
Menace's idea was mine for my custom headers, though i will be doing the old 70s Vette style through air vents. Yep, i know our cars dont have air vents behind the tires. But who sez a Humpter can't. I have removed the fresh air box at both ends of my cowl to help facilitate for room and ventalation of the extra heat behind the fender.

I never liked the tri bolt collector with flat flanges. Doing offset grouping with ball socket design allows both for good sealing and ease of mating if off angle by a wisker.

Though Greyhound, does a great job ironing out issues like pro.

Great to see fixes not patches.



-------------
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: Rebel Machine
Date Posted: Jun/11/2016 at 9:14pm
Nicely done. Nice O'scope too!

-Steve-



Posted By: farna
Date Posted: Jun/12/2016 at 10:29am
Really good job! The same technique would work for using a Jeep six cylinder header in a car. 

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


Posted By: raceral
Date Posted: Jun/12/2016 at 4:29pm
This style of clamp is also an option.

Al


-------------
1969 390 AMX Black,leather, air, 8-Track, auto...


Posted By: Greyhounds_AMX
Date Posted: Aug/19/2016 at 7:35am
I found a set of 3" x 2-1/4" header reducers with a pretty gradual taper, cut off the 3-bolt flange, and ground off the nasty zinc plating.



Once the reducer is in place (and without the 3-bolt flanges) there's plenty of ground clearance.



The 2-1/4" reducers tie in to the original H-pipe with some mandrel bends and flex pipe. The connection between the header and the new piping to the h-pipe is made with a stainless band clamp.



Here's the passenger side header coming together. The initial test fit showed the collector needing to move up 2" and the forwardmost elbow needing to move up 1.5".



So I mounted it to the test head and built up wood to indicate where the original header boundaries were, then marked the new collector location and added spacers to show me where the elbow limits needed to be. Then it just takes some cutting and such to make it all it. On this side one of the middle tubes fit up good, one (#8) had no hope, and the other two were close. I was able to clamp the two close tubes into alignment and tack them, then heat the tubes cherry red with the torch to relieve the stress. The #8 tube needed some extra bend and twist to aim it away from the starter, and then a replacement tube with a section of mandrel bend at the end of it was grafted in.







One thing to note is that I did have to grind a little clearance into the mini-starter gear housing and grind a little off the block as well. That allowed me to clock the starter motor one more hole towards the engine and away from the header. At this point I can install and remove the header easily with the starter in place. I'd have to remove the header to get the starter out, but that's pretty easy.



-------------
1968 AMX 390 w/T5


Posted By: White70JavelinSST
Date Posted: Aug/19/2016 at 12:16pm
I'm likin it Chris.

The welds are pretty too !


-------------
70 Javelin SST, second owner, purchased 1972


Posted By: Greyhounds_AMX
Date Posted: Aug/20/2016 at 9:17am
Thanks! This is a fun project and is really making me see why it's so hard to get a good set of headers. There's a lot of obstacles to miss.

On the drivers side I still ended up grinding a little off the strut rod bracket and putting a clearance dent into the header tube to make sure it doesn't hit. I'm not too worried about a few dings in the headers after watching the Roadkill episode where they dyno test the headers with all the dents in them. No big deal there.

I still need to add the O2 sensor bungs to each side. One will get a plug as I only have one sensor, but at least it'll give the ability to swap the sensor between sides if needed. Once that's done they go back to sandblasting, and then get paint. I'm going the cheap route in every way with these, so they'll get PlastiKote aluminum high heat paint like the hookups did. I've had good results with it over the years, and found that I can cure the paint pretty well with a MAPP gas torch. If they work out well they may get real Jet Hot some day, but I want to make sure the relatively short tubes perform well enough before spending that much on them, and there's still a chance that mods will need to be made to them as well for clearance, etc.

-------------
1968 AMX 390 w/T5


Posted By: Greyhounds_AMX
Date Posted: Oct/08/2016 at 8:44am
I finished the O2 bungs and got them sandblasted again, then finally painted them. I'm using Plastikote HP-14 aluminum high temp paint. Two light coats, then wait an hour, then cure it with a MAPP gas torch. Final cure will come from running the engine.

This paint has worked really well for me in the past.






-------------
1968 AMX 390 w/T5


Posted By: Greyhounds_AMX
Date Posted: Oct/17/2017 at 12:30pm

Well I finally have the exhaust done. Here you can see how the band clamps worked out. With the Wilwood pull slave on the drivers side I ended up with the O2 sensor on the passenger side.




You can also see the heat shields I made out of a big chunk of heat shield material I nabbed off a Corsica. At the tightest spot there's only about 1/2" of clearance, so I may have to tweak these a little depending on how the floor tends to heat up. 

The lowest point of the headers is about level with the bottom of the bellhousing.

 




-------------
1968 AMX 390 w/T5


Posted By: 304-dude
Date Posted: Oct/17/2017 at 12:55pm
Real nice work! Tucked up pretty well.

If you get too hot on the floor, use an aerogel sheet between the heat shield and body.

I plan on using a lot of aerogel on my custom exhaust through the cold air duct / ventilation part of the kick panels and cowl, for through the fender output to side exhaust. Though, being a dropped suspension on my build side exhaust would not work without frame mods, thus my odd idea.

-------------
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: White70JavelinSST
Date Posted: Oct/18/2017 at 5:57pm
Nice Work Chris.

Curious here, how did you route the tailpipes?

What mufflers are you using and can you make a video so we can hear the exhaust note?

Awesome work !



-------------
70 Javelin SST, second owner, purchased 1972


Posted By: Scene One
Date Posted: Oct/18/2017 at 7:52pm
Wow very nicely done!!



Print Page | Close Window

Forum Software by Web Wiz Forums® version 12.03 - http://www.webwizforums.com
Copyright ©2001-2019 Web Wiz Ltd. - https://www.webwiz.net