Super Jet How far to mil 61x head

btmboards

Brett
Location
Oceanside, Ca
I have searched and searched today and have found the question asked but no answers.

Background: I am swapping in a good stock 61x in my SJ while building my other motor. It will have duel 38s very lightly ported intake lightly ported exhaust ports (not opening up cylinder just smoothing transition from cylinder to gasket matched exit), and a b-pipe. I would like to bump my compression up to 180-185 psi (35cc dome range) motor currently has approximately 145psi. Build for freestyle surf need 100% reliability on 91 octane pump gas.

Question: how far do I need to mil the head down to achieve this? Will I need to do anything else like to the domes or edges of them or anything? Or just straight cut it down and run it.
thanks for the info.
 

58vwragtop

Braap Certified
Location
Blue Springs, MO
If you want to just mill it down, usually .025-.030 is the safe range. With that you can get around 170psi. After .030 you have to really start looking at the squish and may have to recut the domes to be able to achieve the proper squish.
 
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