I have recently rebuilt a 1972 GS 455. I went .030 over bore, with a 112A cam from poston ent. and added a holley 770 double pumper street avenger. when I try to set the timing, the timing mark will stay stationary and will not set. how do I remedy this problem and set the timing properly.

If you loosen the bolt that holds down the clamp on the base of the distributor, it should turn and the timing mark should move. Does the distributor turn freely?

What is the timing at now, and what is your target?

-Bob Cunningham