I can't believe it is a valve spring if your compression is good check for a vacume leak at the intake where it meets the head posibly causing a lean misfire. Is it a dead skip?

BN thanks!
Blue Thunder, I haven't checked vac leaks because the plug is black, not lean.
Cartman, yup its a dead skip. Weak springs can give normal compression when cranking, then float the valves when running.
I swapped the springs but I can't fire it up because I creased the exhaust gasket and have to get another today.

GO4Broke,

Vacuum testing is not necessarily to look for vacuum leaks, it is to diagnose engine conditions. Particularly good for sticky valves and other top end problems. Look into it.

BT

Double or triple check the plug wires/ firing order it sounds like ignition.

I will triple check all the ignition because I too lean that way. Blue thunder, thanks for the reminder about vacume testing, your right thats a powerful tool, I just don't use it often. I'll be finishing reassembly tonight and inspect the ignition, then tomorrow I'll fire it up and see what happens. I'll keep you posted...

I rechdecked all the ignition, still NPF. The motor is together and I will run it tomorrow and see what happens.

Well I ran it and the damn thing finally gave me a hint as to the problem. It blew black smoke. I think the port float is sinking and flooding out #2 and #3 which are the front 2 cylinders fed by the upper plenum. I knew it would be something stupidly simple!! I'll be pulling the carb after work tomorrow. This would have been much easier if it had smoked for me before!!