Thumper 401?

[Dallas Lemon]

Hm... what altitude are you at? I'll post when I find the root cause behind my poor power. I have a 360 with 260H. Maybe it is something other than the cam.

Desktop Dyno (see graph earlier in thread) shows the 260H is mediocre 2000-3000. Maybe that is because all the power is below 2000rpm?

Michael

Englewood is around 5300 feet. Have you had your cat checked yet? My CJ is registered in Estes Park and does not run a cat anymore. Just a 3 inch single using the stock manifolds. Like I said, the bottom end is SO strong in this thing. I can go around a corner and not need to downshift. With the T-18, it easily pulls out of corners at 800 rpm in 4th gear and effortlessly accelerates with the 37" MTRs. The 360 would struggle. I had a buddy several years ago that ran 401s in his CJ, and ended up with a 272 cam. We even ran it at Bandimere where it ran the 1/4 in the high 15s at 80 MPH with a T-18, 4:10s and 33s. It would see well over 6000 RPM, and he pushed it to 7000 on a snow run when his rev limiter was bumped up to 7200 unknowingly. It grenaded shortly after that. He went through three 401s and grenaded each one before going back to a 258. My personal feeling was they were too radical and didn't like the extended high RPMs he was pushing them too. I'm sure there are 401's that last at 6000, but not without modifying the oiling system. I'm getting side tracked. Bottom line is I wanted a strong bottom end engine and got one.

[Henry Lavrenz]

Turbocharger.

[MoPedal]

Reading this post really has me wanting a 401. Dallas like you, all I do is rock craw. I run a 304 now (with a final drive of 99.9/1) in my scrambler and it runs fine but I guess I want MORE!!!! I like RPM's too! Your scaring a little on the 7000 .
Is there a post that talks about taking a stock 401, doing some modifications (cam incl) to get the best low/midrange power possible? Is it powerful enough just stock (TBI & headers)? Not sure I need to be thinking about different pistons, rods, etc for strickly woods. Also, I run a Howell TBI (for a 360) on my 304. Will I need to get a different one for a 401?
Any opinions is appreciated!

[Dallas Lemon]

Reading this post really has me wanting a 401. Dallas like you, all I do is rock craw. I run a 304 now (with a final drive of 99.9/1) in my scrambler and it runs fine but I guess I want MORE!!!! I like RPM's too! Your scaring a little on the 7000 .
Is there a post that talks about taking a stock 401, doing some modifications (cam incl) to get the best low/midrange power possible? Is it powerful enough just stock (TBI & headers)? Not sure I need to be thinking about different pistons, rods, etc for strickly woods. Also, I run a Howell TBI (for a 360) on my 304. Will I need to get a different one for a 401?
Any opinions is appreciated!

My crawl ratio, like yours is deep at 115 to 1. With that ratio, a 5 HP Briggs and Straton will have plent of power! The reason I went with the 401 was I had it. The 360 I removed was running the Howell TBI, and I had to upgrade to the Holley Big Block Throttle Body. It is rated at 670 CFM, but I believe it flows more than that. When I ran the 401 with the 360 TB, it would fall on its face at 3600 RPM. The guy tuning the computer recognized the problem as the MAP sensor was leaning out the injectors. Install a bigger bore and all was good! Regarding the cam selection, I would not hesitate going to a 268 next time, or even the 272. The cubic inches alone insure good torque at the low end, especially with your crawl ratio. Going too radical may throw the computer into a bit of a tizzy if you start to affect the vacuum at idle. I don't think a 272 would be that radical, yet. My buddy with a 401 runs a dual pattern cam and gets along fine with it. He runs basically a stock setup with a Performer intake and the Holley 4DI TBI. It doesn't pull as well as mine, basically because of the heads. If you haven't figured it out by now, I REALLY like the Edelbrock heads! Go to Edelbrock's website and check out the information. There is also a thread on this site that discusses heads and the results of different head work.

[MoPedal]

Dallas-When I ran the 401 with the 360 TB, it would fall on its face at 3600 RPM.
The guy tuning the computer recognized the problem as the MAP sensor was leaning out the injectors. Install a bigger bore and all was good! My understanding is that Howell has chips avail for the 401 plus changing a few things on the TB. Was it just a personal preference to go with the Holly or does the Howell have problems fueling the 401?
Dallas- It doesn't pull as well as mine, basically because of the heads. If you haven't figured it out by now, I REALLY like the Edelbrock heads! Go to Edelbrock's website and check out the information. There is also a thread on this site that discusses heads and the results of different head work.
Went to the site, saw the heads, but I'm not really knowledgeable enough to see the difference between stock vs Edelbrock(other than the valve angle). There are a few things you never regret buying such as beadlocks, lockers, TBI, and others.....Edelbrock heads may be one of those things too! If possible, I need you guys help in deciding that.
Also, how critical are the oil modifications?
Again I appreciate all your help!

[jeepsr4ever]

Mopedal..first of all nice Jeep. I read the article on your jeep at Walmart of all places.

Oiling mods are neccesary if your crawling or ramping up the R's. Some simple ones like higher capacity oil pans will fix the RPM issue most of the time but you need a swinging pickup for crawling. I have run out of pressure in my CJ many times before I started adding mods. We have a new swinging pickup for stock and deep sump pans that will save alot of motors coming out soona nd it may be something to check into. Do a little reading around the site..lots of great info.

[MoPedal]

I have looked at the AMC oiling and even I understood part of it but I had trouble getting a lot of the pictures to come up...they are just showing as red X's and I can't open them. I may not be doing something correct trying to pull them up....the pictures I did see were very good.

[Mudrat]

I have looked at the AMC oiling ... a lot of the pictures to come up...they are just showing as red X's

And you won't be abo\le to until they are re-hosted. We had a host change a while back and those pics MAYm not have been re-hosted when that all happend.

MC's gunna have to fix it - I don't have the pics.

'Rat

[MoPedal]

Thanks Rat, I thought I may be doing something wrong!

[Dallas Lemon]

"My understanding is that Howell has chips avail for the 401 plus changing a few things on the TB. Was it just a personal preference to go with the Holly or does the Howell have problems fueling the 401? "

I contacted Howell regarding the upgrade. What I was looking for was a 454 Throttle Body, but they are difficult to find. Howell uses the Holley on their big block applications, so I went with their reccomendation. And, yes they do have pre programmed chips to match your set up, but I have a local mechanic that installs an EPROM and burns it after tuning the computer.


"Went to the site, saw the heads, but I'm not really knowledgeable enough to see the difference between stock vs Edelbrock(other than the valve angle). There are a few things you never regret buying such as beadlocks, lockers, TBI, and others.....Edelbrock heads may be one of those things too! If possible, I need you guys help in deciding that."

When I took the 401 to the machine shop, I consulted with them about using the Edelbrock heads. He knew of no one that had installed a set on an AMC, and he would rather have seen me port the stock heads. I really cannot compare the Edelbrock heads to a set of ported and polished heads. But, the Edelbrock heads better flow characteristics. I don't mean to start a debate at all, but it was my personal choice to go with the heads rather than spend $1000 on head work. I also went with roller rockers, too.