That's interesting. They are red at teh collector, not at the heads.

I could uncork them. but that is a pretty big pain. As well, the exhaust pipe they collect into pretty much stays in place, so seeing the plume would be an effort, for sure.

I wonder if it is possible to take it to a shop of some kind and have something shuffed up the tailpipe (that brings an unpleasant visual)...and get readings on lean vs. rich.

It is pretty easy to change the jets. I could do that, and if it doesn't fix it, maybe that tells me something.

BTW...I have a 45 powervalve in the carb. My vacuum, currently, is at just over 10. According to Holley's specs on lower vacuum, I should divide my vacuum by 2, and shoot for that. So, my opening hg should be 5, and the 45 is 4.5. They don't make a 50 powervalve, but I did see a 55.

Do you think there would be any value to getting an instrument to measure the temp at the header?

Interested in comments on my several thoughts above.

Thanks for your input, everyone!