My head is back from the machinist assembled and final machined. The problem is the chamber volume is off now - when I sent it out they were from 60.5 to 60cc each. I had him take off .020" for a target 57cc (giving me a 10.0:1 CR with 0 deck and a .045 head gasket).

Anyway, now the chambers are 56cc (#1, #2, #6), 56.5cc (#3, #5) and 57cc (#4)

The perfectionist in me wants them within .5cc or less again. I just don't know where the best place to grind on the combustion chamber is. I already relieved it out to the gasket line next to the valves and blended the reliefs into the rest of the chamber wall. The chambers are polished and the little 'dime' in the casting has been ground off.

I plan on duct taping the deck surface, putting in some junk plugs and covering the top with a plastic bag to keep grit out, then washing it real well before assembly.

Wow, within 1 cc is really good. I wouldn't touch a thing.

Lou

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Home of Slant6-powered fun machines since 1988

The "best" place to remove chamber material... grind away any edges of the chamber that over-hang into the cylinder. You have to "test fit" the head to the block, to find the edges to grind-off.

The next best material removal / volume increase process is to do a general"sweep" across the entire chamber surface, removing all the sand casting imperfections.
DD

Thanks guys. Guess I will leave it until I get the block finished.