Quote: Not a vacuum leak/lean issue but more of a too retarded timing issue, I'm not certain how retarded timing causes that much heat.
I can't explain it but it is an issue , really shows it's ugly head when one is breaking in a cam with not enough advance. Headers tubes were turning red just off the heads on the last one I did , crank the timing up to 35 still at the same 2000 rpm and they stopped glowing red.
