Hay Barney,
Have you ever used the head with the cam and valve gear before? I ask
because your problem sounds like what happened to my 360 Dodge last
year. I was using a rebuilt set of heads from Cylinder Heads
Internat'l. No probs with the left head but the right one kept breaking
intake valves just below the keepers. Turned out the keepers were
hitting the tops of the integral valve guides. The tip-off was that the
stem seals were beaten up. The fix was to turn .030" off the tops of
the guides. I presumably got a head that wasn't machined for the RV cam
I'm running, which has passenger car lift.
Another possibility is that the springs may be coil-binding. You'll
get the same kind of breakage. One other possibility, remote since
you're racing, is excessive wear in the valve guide, letting the valves
bind because of side play.
FWIW,
CR
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