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· Premium Member
6,093 Posts
Closed chamber heads are great because they can give a good boost in compression, chambers are about 10-11cc smaller than the open chamber heads. Punching larger exhaust valves in the use of 440s is usually asked because it was just a hair small, but they still have the 2.08 intakes like the other heads. Remove the sharp lip on the edge of the combustion chamber at the same angle as the combustion chamber and you can run 87 octane and around 11:1 compression without any pinging at all. Been doing this for years.
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