How much milled off heads to raise compression

toolmanmike said

Iron heads and 10.5/1 compression will probably detonate on 87 octane. 10.5 with aluminum heads won't or shouldn't. 9.5/1 I as about the limit with pump gas and iron heads on the street. These statements are to err on the cautious side. Too many newbies read the high compression blather and get themselves in trouble.

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This hasn't been my physical experience... $800 Speedmaster heads, $95 to have them checked out, $200 plus cemetic head gaskets (extra thick to lower compression).. intake manifold gaskets exhaust gaskets valve cover gaskets new coolant new oil... $$$..
SAME DETONATION PROBLEM!...
I love my new aluminum heads all I have to do is just add a little race gas so it doesn't run on when I turn it off...
Or you can just throw this real world experience out the window and make something up..