I just replaced the timing chain on the 455 in my GMC. I've got it up on #1 TDC on the compression stroke(driver side front cylinder), dropped the distributor in with the rotor pointing directly at #1 plug wire. I've tried turning the distributor a little at a time and it will not start at all. When I installed the timing chain I installed it dot to dot, but when I put the balance back on, it was not close to being at TDC, the timing mark was at approx 16* retarded. I pulled the front cover off with the engine at #1 TDC and the cam timing mark is at about 5 'o clock, and the crank timing mark is at about 11'o clock. Is this normal? A local shop says that when the two dots are 'dot to dot' this is actually at #6 TDC. Is this true? This still has the points distributor, replaced the points again today with gap set at .016" and dwell is at 29*-30*. There is spark at the points and at the plugs both. Can somebody please help me in getting this beast alive again? I've been trying for about two weeks now. Charles
Charles, I would try it again. Before the gears go on, the #1 piston should be at TDC. Then the dot on the crank gear should be straight up, and the dot on the cam gear straight down. When you assemble everything, the piston should still be at TDC, and dropping in the distributor for #1 firing should be correct. Your balancer should line up. How sure of your balancer are you? Is it old? Maybe it has slipped. The keyway in the balancer should line up with the timing mark of the balancer. Try assembling it again from scratch. Something is wrong. The key in the crank snout should be lined up with the 0 of the timing tab, if the #1 piston is at TDC.
Maybe I got a bad timing set. I got a Cloyes stock replacment. With #1 at TDC, the timing mark on the crank gear is not straight up. I am judging TDC by looking through the spark plug hole and watching the piston move. Charles
With the timing cover on, line up the balancer mark with the 0 on the timing tab. Then remove the balancer, and the timing cover, and the gears and chain. Then reassemble everything. It should look like this.(you can't judge TDC by looking in the plug hole)
Hmm, i'm definately going to have to rule a bad timing set on this one. The timing set I got has the 'dot' on the crank gear 4 teeth to the left of the one in the picture you have posted. Charles
Thanks for the help Larry, I wouldn't have been able to figure it out if you hadn't helped out. Thanks again. Now I need to get back out there and tear it apart. Charles
Anytime Charles:TU: Hope you are able to get it sorted out. Good Luck. BTW, I hope you know to pack the oil pump, or at least turn the pump with a drill to make sure you have oil pressure before you start it. Anytime you disturb the timing cover, there is the potential to lose oil pump prime.:Smarty:
