what cam do I have?

killahxft_jeep

I bought this motor used.. it runs great/ran great but I have no idead what cam it has in it.. should I bother to stick my dial indicator on the intake & exhaust valves to find out? also: It had the stock timing set/chain, and I'm replacing it with a double roller I just got from here... the double roller has 3 settings 0,+2, and -2 degrees... I just bought a new inductive timing light with digital RPM readout so I can time it up perfectly.. If I understand correctly my timing from before with the HEI put me at about 8*BTDC so if I put it on -2* I can set my intial timing for 6* BTDC correct? or am I backwards? thanks.. kinda noob question but everyone has to learn sometime.

tufcj

The cam timing is different than, and doesn't affect spark timing. The -2,0,+2 on the timing set changes the timing of the valve open/close relative to the piston. You change spark timing by rotating the distributor base. Generally, advancing the valve timing (the +2 setting) gives you a little more bottom end torque and throttle response, but you lose top end horsepower, retarding the valve timing does the opposite, you lose some bottom end torque, but gain top end horsepower. If you're unsure, just install it at the "0" (straight up) position and call it good.

killahxft_jeep

tufcj wrote
The cam timing is different than, and doesn't affect spark timing. The -2,0,+2 on the timing set changes the timing of the valve open/close relative to the piston. You change spark timing by rotating the distributor base.

Generally, advancing the valve timing (the +2 setting) gives you a little more bottom end torque and throttle response, but you lose top end horsepower, retarding the valve timing does the opposite, you lose some bottom end torque, but gain top end horsepower.

If you're unsure, just install it at the "0" (straight up) position and call it good.

this is going into a Cj-5 with a t18a/D20 & 3.73's, 32's (for now, going to 4.56's with 35's soon) so I am looking for low end grunt, not high horsepower. so I can set it up for +2.

I hardly ever get up above 3500 in RPMs anyways.. or am I fine going with the "0"?

tufcj

I ran an Isky cam in my 304 at both 0 and +4. I didn't see any real change in the power band, although there was some additional carbon build-up on the valves in the advanced position. To answer your first question, you could put a dial indicator on the pushrod end of the rocker and get some lift specs. Multiply by 1.6 to get lift at the valve. I've got a 77 CJ7, EFI (Howell) 360, Edelbrock performer package, ported/polished 1970 heads, roller rockers. Exhaust is a single 3" system thru factory manifolds (smog rules). I have a T-18/Dana 300. Axles are Dana 44s in both ends with Detroit lockers. I put 4.27s in them when I had 35s. I'm running 37s now, and have 4.88s waiting to install. Bob tufcj

cj5doc

Tuf Cj .... I run 4.27s with 35 and would like your old gears as backups if you want to get rid of them.

killahxft_jeep

tufcj wrote
I ran an Isky cam in my 304 at both 0 and +4. I didn't see any real change in the power band, although there was some additional carbon build-up on the valves in the advanced position.

To answer your first question, you could put a dial indicator on the pushrod end of the rocker and get some lift specs. Multiply by 1.6 to get lift at the valve.

I've got a 77 CJ7, EFI (Howell) 360, Edelbrock performer package, ported/polished 1970 heads, roller rockers. Exhaust is a single 3" system thru factory manifolds (smog rules). I have a T-18/Dana 300. Axles are Dana 44s in both ends with Detroit lockers. I put 4.27s in them when I had 35s. I'm running 37s now, and have 4.88s waiting to install.

Bob
tufcj

I figured 4.56's would be a good compromise as the jeep is still streetable.. I can easily humm along at 55mph without running the revs in my non-OD jeep..

with the 4.56's my revs would be at about 2500 at 52mph.. 2700rpm I'd be at 56MPH vs. my old 3.73's and 32's running 63mph at 2500rpms & 69mph at 2700rpm.. slightly lower for more torque to handle the 35's but not so much of a change that I can't cruise at 55MPH..