ok i have anothere question? what if you set the timeing by the timeing chain with the cam at 6:00 and the crank at 12:00 positions and this would be with marks streight up and down but not my the mark on the harmonic balancer would this cause the engine not to start given that it seems that the mark on the harmonic does not line up with the key way its slightly off the side even on the new ones and also compared to the old harmonic balancer there in the same place the truck does have new harmonic balancer as well on it but i just was looking at this.. would that cause it where it would not start? mine was the OEM#: 10243271 replaced with the Dorman 594-121 if you look the timeing mark on the harmonic balancer is slightly off? now it would sem to me that this would set as ATDC or is it BTDC based on that line because its not lined up with the keyway and i allways thaught that the keyway was true Zero on the crankshaft please reply..
1996 GMC K2500 timeing issue on 1996 GMC 2500 Pickup
by wayneself in Payson, AZ on January 01, 2010
ANSWER by dandd , January 01, 2010
If the Cam and Crank line up according to the documentation, then you should be cool. The Harmonic Balancer does not effect timing. Timing is the relation ship between the cam shaft and the crank shaft. The Key way does not necessarily meant TDC, on any motor. Just make sure that the Distributor is lined up properly, meaning that the rotor is pointing to #1 cylinder on the compression stroke. I often do this manually, meaning I tap the engine over with the starter and feel with a piece of wire where exactly top dead center, compression stroke, really, exactly is.
ANSWER by Visitor , November 17, 2010
Easiest way to be sure is bring #1 to TDC then check where the rotor is pointing is it pointing to #1 plug wire? If this is ok then leave plug out and turn engine over a few times with plug in the plugwire on a ground check to be sure it is firing when at compression, is this happening? Either use a remote starter or have someone turn the key for the above step!