Originally Posted by
36 sedan
TDC is the position of the piston, nothing can change that short of a broken crank. The cams timing will change valve opening /closing and can effect compression, but will not change TDC. Distributor placement will change spark timing in relationship to compression, but again will not change TDC.
If TDC is on #1 at the compression stroke (both valves closed) and the timing marks at the balancer do not align, either the balancer has slipped or the wrong balancer pointer combination are in place. Also a broken key on the crank can cause this.
However, a compression test will tell us the health of the combustion chambers in this engine and let us know if we are chasing our tails. Thus my recommendation. IMHO, a compression test should be the first thing done to an unknown motor...