"670 heads usually demand a premium. They are also closed chamber. I would rather use high compression heads that are open chamber, which started (I think) with 061 heads from 1967, and other heads from 68-70."
Do the closed chambers's valve location not work well with the smaller bores?
https://forums.maxperformanceinc.com...7&d=1610800822
I've read conflicting forum posts about detonation, are closed chambers more detonation prone or are they just usually high comp chambers to begin with?