401 Cam Question

[1980_Cj7]

We've been researching and have settled in on a Comp Cams Xtreme Energy 256 cam for the 401 being rebuilt for our rock crawler CJ7.

We see that particular cam has been discontinued here on Bulltear's for sale page. Any particular reason?

Also, does anybody have any first hand experience with that particular cam in a 401?

[jeepsr4ever]

Comp cams numbers on the 256 werent working well when we went from a stock 2bbl (from a 360) to a performer and a 650cfm carb. We were so unimpressed that we wont sell another one. Its just too small

[1980_Cj7]

That is what the tech from Comp Cams recomended. What have you all found tried and proven. Keep in mind its for mostly idle and low rpms for crawling with lots of torque to climb the bolders without gobs of go pedal.

[Dusty]

the techs at comp cost my friend jim and my self a few rebuilds on thier recommendations for our first few 401s and 360s. they ALWAYS under cam the AMC's especially 401's they treat em like SBC's and they arent they need to be trated like B 383's and RB 440s , the recommend the same cam for a 304, 360 and 401 when you give them the same specs and parameters. Crower was fairly helpful when i did my cam the second go around

single pattern .510 lift 226* dur @ .050 and a 112 lobe seperation jsut a hair on the wild side but it doesnt sound or run like it has a large cam in it at all. very trail worthy, idles over things great and it has the higher rpm power range too for the street and dunes. Dont be bashful with the 401. I have one friend running .496 .512 224/ 228 dur @ .050 on 112 lobe sep with 9.8:1 and i like that engine a little more than mine at times. another friend in his cj is running 9.8:1 and a .521 /.534 226/230 dur @ 050 112 lobe sep cam from crower and though it definately lopes amazingly enough it too does really well on the trail idles down to 600 rpm with no issues and just screams when you open it up.

all the above motors are in cjs mine is a cj8 with 4.88's and 5spd od, 35's the other 2 are a 5 and 7 both with 4 spds and 3.73 and 4.27 gears and 33's and 35's

food for thought not many people know these motors

[1980_Cj7]

Thanks Dusty that is the kind of information I am looking for, now if I can get a few more to chime in like you did!

[1980_Cj7]

Did you have to do anything different with the valve train with lifts that high, i.e. different rockers, different pistons, etc.?

[Dusty]

all of the engines run roller rockers 1.6 ratio and at the time of the rebuild we put new springs in. .... they were just the springs that came with the cam so no since it was at the same time as the rebuild nothing too extra have to put in new springs regardless so it was always timely.


also should add that my cam has a sharper ramping on the cam.... adv duration for mine is 274 w/ 112 lobe sep where as the 479 lift howards cam i spoke of has a 292 adv dur with 114 lobe sep. the 479 cam is definately lazier to come on than my cam the torque is flatter and not as peaky as mine.


summit has the 9.8:1 TRW forged pistons for cheap. IIRC rings, pistons, bearings, you will need .010 longer hardened pushrods from summit and seal kit was $680 or so. custom ground Cam w/ lifters from crower were in the $250 ball park. machine work was $325 I used a different pushrod because i went with the Edelbrock heads and i already had the roller rockers


You can do it cheaper than i did but that gives you an idea

[1980_Cj7]

Ok I am still waiting on the machine shop to call me back with their findings. Was "suspose to get called by the end of the day" everday since last Friday. If these keeps up it may be heading to another shop for the actual work!
I will keep this updated, and all the help is appreciated with our "first" 401 build.

[1980_Cj7]

Finally I called agian and they told me that the block needs bored and the crank needs turned. Rods look good, still working on the heads.
I will be dropping off the oversize pistons from my other parts motor to see if they can be used.

Still on the cam thing. Can someone provide numbers that can be compared to aftermarket cam specs. I dont know how to compare the factory specs how they are given to see what it would be equivalent to in an aftermarket cam.

[Dusty]

just out of curriosity why are you re-using oversized pistons from another motor??? are they Cast pistons to boot? dont waste your time if thats the case, you are spending the money for good machinework why risk putting pistons that already have wear patterns for another block into a freshly bored motor.

What compression ratio are you hoping to end up with. 9.8:1 will run on pump gas no problem.


dont bother with the stock cam spec. they ran the same cam in 304, 360 and 401 that will give you an idea how choked your motor was. the .479 lift howards cam is a mild RV style cam similar to the stockr but with better duration #'s and lift stock was close to .450