71455
to make things a bit easier; let's say the 455 fires 12 degrees before TDC, - that's when both valves would be closed, do your test on the valve springs by rotating the engine, using the rotor to determine each cylinder's firing point. then you can go back and forth making sure both the intake and exhaust valve were opening - they should each move about 1/2", and not hit the top of the piston.
Butch
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