401 Cam Question

[zero cool]

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

The 401 had a different cam than the 304/360. According to the FSM for my 77 Cherokee, the cam specs are:

304/360 cam:

Cam lobe lift: 0.286 inch (with 1.6:1 rocker, you get 0.4576 inch)

Intake valve timing: open: 14.75* BTDC; close: 68.75* or ABDC

Exhaust valve timing: open: 56.75* BBDC; close 26.75* ATDC

Valve overlap: 41.50*

Intake duration: 263.50*

Exhaust duration: 263.50*

401 cam:

Cam lobe lift: 0.286 inch (with 1.6:1 rocker, you get 0.4576 inch)

Intake valve timing: open: 25.57* BTDC; close: 90.75* ABDC

Exhaust valve timing: open: 80.80* BBDC; close 42.75* ATDC

Valve overlap: 68.32*

Intake duration: 296.32*

Exhaust duration: 303.55*

You can see that there's just a little bit of difference between the two cams...

[Dusty]

my bad wasnt stock lobe seperation 115 or something like that also

[1980_Cj7]

After talking with the machine man we decided on new pistons, most likely Speed Pro forged, and Comp Cams Magnum 270 cam kit. Now to find the cheapest prices, leaning toward ebay??????