The 401 revisited

[Elliott]

Originally posted by jeepsr4ever:
where is the 401 thread?????

Here: http://www.ifsja.org/ubb/ultimatebb....;f=10;t=000117

We got cut off, some people couldn't handle the banter and felt compelled to read/complain rather then ignore. Maybe we can keep the discussion to a level that won't offend.

Still need to examine the torque curves of a 500ftlb 401 compared to a 500ftlb 500 to see if they do compare or if the 500 builds torque faster. I think with the right cam in the 401 it might be able to match it.

The Caddy is cheaper only to a point of build, barely above stock.
Still the specs don't lie (or do they? John ran a dyno and came up with the same thing). A 401 builds almost twice the torque difference between it and the 360 in 41 more CI. The Caddy, with 99 CI on the 401 required twice the CI to obtain the same (very close) torque gain. This is comparing the lowest common denominator 401 (Jeep) to the lowest common denominator 500 ('76). If the torque difference between a 360 and 401 were negligible as was suggested then the same could be said for the 500 over the 401.
Pretty much everybody spending money to rebuild a motor is going to be buying new pistons/cam and if it's stock, putting on a new manifold/carb and if they are wise... balancing it.
Do that lil bit-o work to a 401 and you are at 500ftlbs with the right choice of cam, and you're still running a stock exhaust for low end torque while running on pump gas. What amount of torque does the same mod do for a 500, and if it does not build the torque as fast as the 401 why not?

The CI factor doesn't hold water, cost factor involved in a low level of build is definately in the 500's court.

[ December 13, 2003, 10:53 AM: Message edited by: Elliott ]

[jeepsr4ever]

sheesh i thought the 401 thread was long winded but some good info in it

[Elliott]

Here's the Dyno specs that John ran for us. I don't know if there is a way to have the torque curve tracked, but that would be slick. I might have to pick up one of these desk top dynos like his, I didn't know they were that accurate so I was always a little uncomfortable claiming that my 401 built the 500ftlbs my builder showed me on his dyno sheet. If they are within 10% on horsepower that's pretty darn good.

From John V before he ran the dyno:
"I have a nice piece of engine building software I acquired from a machinist friend. I will be using it to make 1 each of the above mentioned mills to show their potential. All the baseline specs will be the same, compression ratio, induction, exhaust, ect, ect, ect. This software has been proven accurate against actual dyno numbers within 10 hp and 7 ft pounds on several occaisions. I will have stock valvetrain components, heads, windage, bearings, pistons, a .03 overbore, a 750 cfm carb, I will, when available use a stock hi po cam grind, when not available I will use a similar profile cam. If anybody wants additional engines thrown into the mix I can add those as well, just post here."

Lowest common denominator engine specs for stock motors:
AMC Jeep 401(1974 - '78) 215hp - 320ft/lbs
Chevy 454 (1981 – ’86) 230hp - 360ft/lbs
Ford 460 (1980 Net) 212hp - 339ft/lbs
Caddy 500 (1976 Net) 190hp - 360ft/lbs
Mopar 440 (1976-‘79 Net) 225hp - 330ft/lbs

From John after he ran the Dyno:

"Well with only having to change the major components it was quicker than I thought!

Here are the #’s in order of most peak torque

Chevy 502 : 481 ft lbs @ 3500 avg 403 - 381 hp @ 4500 avg 254
Ford 460: 472 ft lbs @ 3000 avg 372 - 300 hp @ 4000 avg 214
Buick 455: 455 ft lbs @ 3000 avg 342 - 279 hp @ 3500 avg 195
Mopar 440: 451 ft lbs @ 3500 avg 376 - 373 hp @ 5000 avg 244
Chevy 454: 441 ft lbs @ 3500 avg 378 - 383 hp @ 5000 avg 245
Pontiac 455: 435 ft lbs @ 4000 avg 339 - 381 hp @ 5000 avg 231
Ford 427: 430 ft lbs @ 4000 avg 362 - 384 hp @ 5000 avg 239
AMC 401: 413 ft lbs @ 3500 avg 354 - 337 hp @ 4500 avg 223
Mopar 383: 391 ft lbs @ 4000 avg 349* - 384 hp @ 6000 avg 283*

* The baseline was set to run from 1000 to 5500 rpm, as the 383 made peak hp @ 6000 the average hp and tq numbers for it are not really an apples to apples comparison.

All the figures are based on similar type components so yes, all these mills can be built better. The point was to get an idea of what kind of power you would get from each mill in a similar rebuild. I used a holley 750 vac secondary carb on a production type dual plane manifold, stock exhaust mani's with dual 2.5" race mufflers. the coolant temp used was 160* intake air temp was 60* using 91 octane gas."

"The software I used is made by these folks:

http://www.performancetrends.com/

For anyone looking for an accurate way of predicting what an engine will do. I have the standard 3.0 version. the pro is just insane!"

[ December 13, 2003, 11:40 AM: Message edited by: Elliott ]

[jeepsr4ever]

hey [img]smile.gif[/img]

[Elliott]

I needs to get me that dyno software.

http://www.performancetrends.com/EA30.htm

[ December 13, 2003, 12:08 PM: Message edited by: Elliott ]

[Stuka]

hod on, the test above was done by software, or on a dyno? if it was done on a dyno, its pointless to post it.

[Elliott]

John V:
"This software has been proven accurate against actual dyno numbers within 10 hp and 7 ft pounds on several occaisions."

That's good enough for me, check their site out.

[Rogue]

what does a "high-po" engine have that makes it "high-po"

- forged crank - 401 has
- forged rods - 401 has
- good flowing heads - 401 has
- favorable rod ratio( long rod ) - 401 has
- relatively light pistons ( small compression height ) - 401 has
- big valves - 401 has

so what's bad about a 401 again?

cast pistons - if you are rebuilding and engine you are probably replacing them anyways and one step further if you are building a "high-po" engine you'd be using forged anyways - i would say this yin has been yanged

oiling system - easily overcome with a $30 mod

timing cover - bulltear is working on chrome or coated or something or other ( it was a long time ago when i read about them ), crown's quality has been greatly improved - cost of timing cover offset by not having to buy oversized valves and machine work for oversize valves - or having to buy a different head period a stock head with a little pocket porting will flow awesome

seems to me the small amount more ( relatively speaking ) it costs to build an AMC is more than made up for in sheer brilliance of design

[ December 13, 2003, 01:53 PM: Message edited by: RogueStar ]

[Elliott]

RogueStar,
AMEN

[Rogue]

dang totally forgot about the valve train -
SBC = expensive girdles, guideplates, etc, etc to prevent deflection under load
AMC = factory shaft mounted rocker don't suffer near as bad deflection problems and will accept a higher lift cam more readily without problems with stock rockers than say SBC

[Elliott]

You got that right.
And then there is thick main webbing and more nickle in the block then any other block made. If you want 4 bolt mains (and I've never heard of them being needed) they are available and install with very little machining. Top it off with exhaust headers that flow great.

[Stuka]

elliot: but I have also seen the software varients be quite a ways off. I still rather see real numbers

As for 4 bolt mains, I have heard more cases of the caps cracking from them having less material, then 2 bolt mains having a bolt snap. (granted this is with SBC's)

[John V]

The perf trends software I have was used by the guy I got it from to build 100+ 900+ hp marine engines including a pair of twin turbo 572 bbc's that make 1400hp each. The mills (not counting the fuel injection, exhaust, computer, or turbo systems) cost 60k to build, each! The software was within 10 hp and 7 ft pounds on these particular mills, and pretty dang close on the rest as well. That's close enough for me!
P.S the folks that built the tranny's (2 spd tf 727's) and drives (modified speed 6's) came up from aussie land and spent the $$$ to run these again after the mills DESTROYED about 100k worth of parts under that were warranty. They propell a 50' scarab cig boat with full cabins & ammenities (read HEAVY) to 74 mph! Man that boat is sweet!

When I have the time I will run the #'s again and give the spec for all the mills from 1k to 6k rps. I will also be running them with some different parts. If anyone knows spec on a favorable cam for any of the mills listed please post them here, or email them to me. Let's do some bench rebuilds of each motor with different $ levels and see what comes out in the end. Sound like a plan?

[Crazy_Jeepman]

Originally posted by RogueStar:
AMC = factory shaft mounted rocker

They Do???? I never seen Rocker Shafts in the 258, 304, 360, or the 401. Of course I may have had my eyes closed.

[Elliott]

Sounds good to me John. Wish I still had my cam specs to enter, I remember it was ~262 deg and high lift, about .540 or so, but I don't even have a guess on the rest.