milling heads for comp ratio increase

JBurch said
The surface to volume ratio when milling heads is as follows: on a small chamber 273/318 head, for every .0053 inches milled off the chamber face will reduce the volume 1 CC, for every .010 inch removed from the chamber face, it is recommended to remove .0095 from the intake face. Milling info from "How to Hot Rod Small Block Mopars" by Larry Shepard. Heads can be milled up to .060. Loose rule of thumb is, 10cc removed equals 1 point of compression. Hope this helps

Sure does help - That's great info JB, exactly what I was looking for in a concise paragraph. Along with Tool Man's thread, it's all great. Had to think about these numbers though. I am sure these are for closed chamber heads - you say 'small' chamber, which are '64 to 67 year heads (57cc - there were two different casting numbers in the 273 heads). Then they went to open chamber (60cc) which are what mine are unfortunately. By those numbers, to get mine back to 57cc, would need only about 16 thou milled off (3 x 0.0053). But I think I would need more if mine are open chamber. If mine are around 8.8:1 now and wanting 1.0 extra, I think a full 50 thou would be necessary. I am even considering making my own gaskets to suit, out of sheet copper. A metal place just up the road can supply 1/2mm (0.020") copper for this. Sounds like a rather big job though! But I have new set of hole punches.

According to many people, and some here I have read on this forum, these are just junk 318 heads, nothing special. Maybe true, but they're all I have with my budget - I have another 318 and two 340s all needing cash thrown at them also.