1991 cherokee engine rebuild

osnixpero · #1 (**permalink**) 11-06-2009, 01:08 PM

i'm rebuilding an engine for my 91 cherokee and i'm trying to give myself a migrain figuring the timing chain/gear enigma. according to the "book" the cam gear mark sets at the 12 o'clock position and the crank gear mark sets at just before the 3 o'clock position. if this were my cj it would be a no brainer as the marks would line up and the rest would fit. could one of you wiz-bang fellows clarify this quandry?

SteelHeadz · #2 (**permalink**) 11-06-2009, 01:17 PM

Ahhmm, which engine are you reffering to?

osnixpero · #3 (**permalink**) 11-08-2009, 06:02 PM

4.o 6 cyl

SteelHeadz · #4 (**permalink**) 11-08-2009, 08:55 PM

This is the 4.0 timing marks.

osnixpero · #5 (**permalink**) 11-09-2009, 08:58 AM

the timing marks i know. the positioning of them is the question. the chiltons says that for only the 90-91year modles the marks are to be set with the cam mark at the 12 oclock position and the crank mark at the 230 or so position (near three oclock per book) so that there is 15 pins between the marks. is this something new in engine rebuilding or do it old school and set the marks as in your picture?

carnuck · #6 (**permalink**) 11-10-2009, 01:49 AM

Quote:

Originally Posted by osnixpero

the timing marks i know. the positioning of them is the question. the chiltons says that for only the 90-91year modles the marks are to be set with the cam mark at the 12 oclock position and the crank mark at the 230 or so position (near three oclock per book) so that there is 15 pins between the marks. is this something new in engine rebuilding or do it old school and set the marks as in your picture?

Childrens is the problem. Take what they say with a grain of salt. I use the overlap method of setting chains. With the #1 at top dead center, either the #1 rockers are at overlap (roll the motor either way and the intake or exhaust start to open/close) or #6 (#4 on 4 cyls) is. I do that with the rockers loose so the piston/valves don't make contact.

SteelHeadz · #7 (**permalink**) 11-10-2009, 07:52 AM

I agree, Top dead center is your verification for setting up the timing . That illustration is from the factory service manual.

osnixpero · #8 (**permalink**) 11-11-2009, 09:11 AM

that is what i was going to do in the first place, run the #1 up to tdc as i would for my cj. but what is the significance of the 15 pins between the timing dimples and will setting the timing gears as in the pic affect timing as this engine (when finished and installed) will be timed by the computer not by moving the distributor? i just want to get it right on this motor. i wish it was as easy as my cj!