how much would i have to shave off a head with 76cc chambers to get 70cc chambers? also if i use shim gaskets with the shaved head will i have to mill the intake? the block has not been decked. using flattop pistons with 4 valve reliefs. trying toget close to 9.5 to compression.

 

approx .050-.060" usually. thats about the limit for flat milling anyways. (intake valve seat)

You may have to enlongate the intake bolt holes.
May have to shave the bottom of the intake manifold where it meets the china walls.

I had .060" shaved heads on a decked block with thin shim gaskets and on one intake I used I had to shave the bottom of the intake but did not shave the intake manifold matting faces to fit it.

The intake port openings will be raised relative to the cylinder head ports. So if porting the heads, raise the roof a little and use a 1205or 1206 gasket. The port floor match is not as critical as the roof.

i shaved the bottom of my intake by hand with a 7" electric grinder/sander and a 80grit disc.

You won;t know for sure if the port faces will require milling untill you mock it up.

 

how many cc's change is it per .010 millied?

 

.006" cut for a 1cc reduction. Approximately. ( general guideline)

usually requires a little more than this.

If you want to end up with exactly 70cc's you should cc the chambers before cutting as they vary a bit.