Mark,

Thanks a ton for the suggestions.

I did switch to multigrade- obviously too soon.  I'm going back to
multigrade tomorrow.

Compression was 74, 74, 72, 74 over 80.

I've been playing with the timing and can get a bit more CHT.  I do intend
to raise the timing some.  But it doesn't make enough of a difference.

I'll try to the suggestion on the electrical interference.  Like your
problem, mine is only at high RPM.  It's driving me up the wall.

Matt

ps.  aren't excess speed problems frustrating? (don't forget, I have a 200
HP angle valve to explain the speed).