401 engine build ...

[skid2964]

Ok, I am starting to plan for my 401 engine build. I want (I think) to make at least 300HP, although I had wanted to use Holley pro-jection, it says that it is good for up to 275HP. I guess close is good enough? anyone uses this induction system for higher the 275HP engines?

I have been playing with my dyno 2000 program plugging in different cam specs. It listed the edelbrock performer cam by name, anyone using the edlebrock performer cam kit? According to the dyno 2000 simulation, it will make 300HP if I use headers. Thats another question, I used to race full sized Pontiacs and had to make cutsom headers, so I have no idea who makes the best fitting and most quiet headers for a FSJ. any suggestions?

[AMX factor]

I've heard both good and bad for the Holley EFI system. Personally wouldn't use it. The Edel Performer cam is ok but it lacks a bit in the exhaust duration. The Comp Cams 260H and 270H are better cams. The Summit cam that a lot of guys here use is pretty healthy also.

Thorley and Edelbrock make the best headers for FSJ's to date. They run about $500 a set. Edelbrock is releasing a "shorty" FSJ header in the next month or so. Not sure how cheap it'll be but I bet it's still gonna run $300. I have a set of Edelbrock regular FSJ headers and I really wonder how they are gonna make them shorter the ones I have are short! Hedman makes an FSJ header also about $175 but most feel they are lightweight and burn out fast, less than 2 years usually.

[Elliott]

If you are building a low rpm torque motor you will do better to run with the iron exhaust. AMC heads flow excellent, if you open up the exhaust flow it's going to rob your low end.

[skid2964]

Originally posted by Elliott:
If you are building a low rpm torque motor you will do better to run with the iron exhaust. AMC heads flow excellent, if you open up the exhaust flow it's going to rob your low end.I assume the stock exhaust manifolds from any Jeep will do? Are the older ones better? I assume they all have the air inj holes in them?

[Elliott]

I've got a set of non-smog iron exhaust manifolds, don't know what AMC they came off of though, CJ?
If you can't find 'em I used to just stuff a bolt in the injector hole. Getting all of the old injector bolt out of the hole is the biggest PITA.

[skid2964]

Originally posted by Elliott:
I've got a set of non-smog iron exhaust manifolds, don't know what AMC they came off of though, CJ?
If you can't find 'em I used to just stuff a bolt in the injector hole. Getting all of the old injector bolt out of the hole is the biggest PITA.Do they appear identical to the manifolds on your FSJ?

[Oracle]

If you do a search for AMC racing i think, there is a thread on the board that mentions and gives the contact info for a fellow somewhere round West Virginnia or thereabouts who used to race prep AMC engines. Word was that he knows all there is to know about warming up the AMC 360's and 401's and just as importantly, how to make them live long and prosperous lives smile.gif

oracle

[Smooshy]

Hey david, you know how I told you my CJ was dyno'd at almost 380 hp. Thats with a comp 268H,(among other things, 10:1 compression) few guys on here use that cam..

[Chero77]

I am running the SSI 10300 cam which has the same specs as the Performer cam. Actually, its an identical grind. Anyway, the cam is just a little bigger than the stock 401 cam. It idles smoothly at 900 rpm and above. Anything below that is raspy. The engine starts pulling at about 1200 rpm and is very strong between 2000-4000 rpm. My opinion is that for a heavy vehicle with a stock automatic, this about as big a cam as is practical. Anything bigger and you will need a torque converter with a higher stall speed to get into the engine's power band. With a manual transmission you can run a slightly larger cam and still maintain good streetability. Basically, any of the split pattern cams with around 204/212 degrees of duration (at .050) should work fine. I tried most of them out on Dyno 2000 and they all performed about the same. How well Dyno 2000 conforms to real life though is anyone's guess--but its probably in the ball park.

[skid2964]

Originally posted by Chero77:
I am running the SSI 10300 cam which has the same specs as the Performer cam. Actually, its an identical grind. Anyway, the cam is just a little bigger than the stock 401 cam. It idles smoothly at 900 rpm and above. Anything below that is raspy. The engine starts pulling at about 1200 rpm and is very strong between 2000-4000 rpm. My opinion is that for a heavy vehicle with a stock automatic, this about as big a cam as is practical. Anything bigger and you will need a torque converter with a higher stall speed to get into the engine's power band. With a manual transmission you can run a slightly larger cam and still maintain good streetability. Basically, any of the split pattern cams with around 204/212 degrees of duration (at .050) should work fine. I tried most of them out on Dyno 2000 and they all performed about the same. How well Dyno 2000 conforms to real life though is anyone's guess--but its probably in the ball park.Yeah, I was playing around in Dyno 2000 also, it doesnt really support the AMC. I am thinking about getting Dyno2003 (DynoSim2003), it supports AMC engines completely.

I am considering an "in-between" grind. That being in between the edelbrock performer and the summit k8600. (209 dur @.050)