[DADZZ64]

This might be a dumb question but the only way i can find out is to ask you guys ... I put a set of timing gears on my 455 and notaced that to line the timing marks on the gears up i had to advance the cam by about a degree or 2 compaired to the stock timing chain and gears.... it runs .. but iam wondering about compression i did a test a little while back and notaced some low cyilinders would valve timing play a role in this or is it a ring problem

[Jack Gifford]

Valve timing would not cause different compression readings between cylinders. It could be related to piston rings, but more likely has to do with quality of valves seating.