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401 street strip build

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amx73 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx73 Quote  Post ReplyReply Direct Link To This Post Topic: 401 street strip build
    Posted: Jul/12/2018 at 9:47am
I recently picked up a 71' Javelin that I want to build into a street strip car. I have a standard bore 1973 401 long block. Weisco .030 over, 9.5:1 comp(w.58cc heads) forged pistons, ARP rod bolts. Was going to use the stock heads, Air Gap intake, Holley 750cfm double pumper, Hooker 1 7/8 tube headers.

The cam I have is a hyd flat tappet Lunati that CC used in there 370 build. It was the "small cam",

221/230 @ .050, .484 in/ex lift, 108LSA   Made 437hp@6000, and 470lb/ft torque@3900(but, that motor was 10.5:1 comp)

Transmission is either going to be a TF727(trans go shift kit, and red clutches) with a 10" 3000rpm converter, or a TCI 200r4 with a (2600-2800rpm conveter)  I have the Advanced adapters kit already and have used this trans behind my other 401!

Rear: AMC 20, 4.10 gears, Moser axles, and Eaton LSD

I want the motor to be pump gas and street friendly, and push the car to mid 12's.

What do you guys think about this combo?
Red means run son, numbers add up to nothin'!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: Jul/12/2018 at 3:53pm
I like it,
might want to tweek the heads a little,
and go with a faster acting cam with a little more lift.

At some point the RPM intake could be your limiting point 

Also those Wiseco pistons are awesome,
but going to .030" the first time through the engine limits you on future rebuilds.

Autotec knows how to make AMC pistons, and will make Standard bore, or whatever you'd need to hopefully save the .030" bore for the next time you rebuild.

71 Javelin AMX P-code Go pac 360/4spd/3.91's
was Green/green now T/A red w/blk leather

88,89&98 Jeeps
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mixed up View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mixed up Quote  Post ReplyReply Direct Link To This Post Posted: Jul/12/2018 at 11:58pm
after building many motors my opinion on cams is go big or go home because I have always put bigger cams after putting the car on the road I run 540 lift 280 duration solid cam on my 290 drive it on the street take it to the strip love the pull it has at top end 0-6500 power curve its fun to drive my opinion the lift it limiting the power. you might see mid 12's on it
69 amx 290 auto
65 220 290 4spd
80 ford fairmont
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amx73 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx73 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/13/2018 at 7:56am
Originally posted by mixed up mixed up wrote:

after building many motors my opinion on cams is go big or go home because I have always put bigger cams after putting the car on the road I run 540 lift 280 duration solid cam on my 290 drive it on the street take it to the strip love the pull it has at top end 0-6500 power curve its fun to drive my opinion the lift it limiting the power. you might see mid 12's on it


I'm not dead set on the cam I have. But, I have it. I thought with the 9.5:1 compression it would limit the amount of lift? I had an issue with a 8.5:1 motor that i used a .540 lift cam and it fell on its face at about 4500rpm. I didn't know it was 8.5:1 because after it was taken apart I realized the engine builder put the wrong pistons in it!!!


Red means run son, numbers add up to nothin'!
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amx73 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx73 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/13/2018 at 8:00am
I have heard that .030 over on a 401 is its limit without over heating issues. The motor in my 73' AMX is bored .020 over, and she runs kinda warm. I will check out Autotec. Even if the pistons are $500-600, it will eliminate some machine shop costs.

Once the motor for my 73' AMX is back together and running, I'm going to drag the other 401 from under the stairs in the barn, and get it apart. To see where its at...

Originally posted by jpnjim jpnjim wrote:

I like it,
might want to tweek the heads a little,
and go with a faster acting cam with a little more lift.

At some point the RPM intake could be your limiting point 

Also those Wiseco pistons are awesome,
but going to .030" the first time through the engine limits you on future rebuilds.

Autotec knows how to make AMC pistons, and will make Standard bore, or whatever you'd need to hopefully save the .030" bore for the next time you rebuild.

Red means run son, numbers add up to nothin'!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hurst390 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/14/2018 at 8:30am
I would run smaller headers on that combo..
SC/Hurst Rambler

11.62 120

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Greyhounds_AMX View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Greyhounds_AMX Quote  Post ReplyReply Direct Link To This Post Posted: Jul/14/2018 at 2:24pm
I think with that cam you will be right at the edge of what you can run with good pump gas, as the DCR comes out to 7.82, and I've got a conservative limit listed of 7.75 for 93 octane with zero deck. If you can tune the timing right it'll make the most torque that way of course, but I'm sure it'll take some effort. It'd be good to have a distributor or ignition that lets you customize the advance curve easily and beyond what you can do with just springs and weights.

The Car Craft build using that cam was about the same deal, in that they ran just a little beyond what most folks would accept for a DCR limit in that 360, but I expect that all of their dyno testing was done with race fuel so knock wasn't an issue. They'd probably have to back off on the timing curve a little with pump gas.

The cam uses Lunati's UH4 and UH9 lobes, which are their "Baseline Hydraulic" 0.842 lobes that are just a smidgeon faster in the 0.050"-0.200" range than the Crane HMV lobes and intended to be very streetable. They should be nice and quiet and low risk.
1968 AMX 390 / T5
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amx73 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx73 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/14/2018 at 9:21pm
Checked out the motor. Standard bore, cylinder walls look great, crank is standard and in great shape too! I spoke to Autorec and a set of standard bore forged 10:1 pistons, are $610 plus shipping. I'm going to get the rods rebuilt with ARP bolts.

Heads are 993 castings. I was going to get them rebuilt with some mild porting(gasket matching) and that's it. Air Gap Intake, Holley 4150 750cfm carb, HEI distributor, and hooker 1 7/8 tube headers. TCI 200r4 with 2600-2800 stall, and an AMC 20 with 4.10s and a posi.

Now...I'm not married to the cam I have, and I'm open to suggestions. It's going to be primarily a street motor.
It's going in my other 73' javelin SST, and I'm going to put the 360/727 that's in it in the 71'!
Red means run son, numbers add up to nothin'!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Jul/14/2018 at 11:36pm
Target 1/4 Mile ET in seconds kinda dictates everything...
12.00 sec is tied to 110 mph.  Choose a Target Engine RPM at 110 mph.
110 mph, target engine rpm, and tire size determine Ring & Pinion.
Trans gear ratios, Converter quality, & target engine rpm
determine Shift Points and engine rpm drop gear to gear.
Chose Camshaft for Engine RPM at 110 mph target speed
and Engine rpm drop after each shift...
Max Torque to Max HP, 3 times... this points to what Camshaft...
1-2 shift is usually at a different rpm than the 2-3 shift.
What rpm the motor drops back to after each shift is almost
more important that what rpm the shift is initiated at...

A lot of hot air... but I used it as go-by...
My car shoulda ran 12.00 flat but 12.6x is the best I got...
I was loosing 4.5% to 5.0% somewhere, had the MPH but not the ET.
It was a "cheap" B&M Super HoleShot 3k Stall $400 TF Converter...
It had 5-7% Slip at the top end... probably the culprit...
Needed a "good" 9" maybe 3k Stall ~$1k Coan Converter (less top end slip).
343 block, 304/360 Crank, cast slugs, iron heads, Elgin Cam, Torker, Holley, 3.73


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Post Options Post Options   Thanks (0) Thanks(0)   Quote PROSTOCKTOM Quote  Post ReplyReply Direct Link To This Post Posted: Jul/15/2018 at 12:58am
Those headers will be to large for that combination and RPM range. It would run better across the entire RPM with stock iron than it will with 1-7/8" headers. Just like over camming you can over header it and your heading there. While I will admit 1-5/8" headers will not look as cool as 1-7/8" your going to be giving away torque and HP. It's all about the combination and with everything else they are way out of place.

Tom
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