Lou had previously commented about a angle milled head which gave him a compression ration of over 10:1. Being a "neophyte" ...I have not heard of the term "angle milling". Several more knowledable engine builder here have not either. Is this a new techinic? What are the pros and cons of a angle milled head? Comments appreciated...

A no-longer-active member at ss.com was angle milling his head before he dissapeared w/ mixed results. The good: The angle mill seemed to help 'squish' the intake charge to the plug side of the head, which should make for slightly better combustion. The bad: you cannot angle mill much before getting the head bolts in and head gasket sealing becomes an issue.

That is the gist of what I remember on angle milling. I'll let others w/ experience with this chime in.

-S/6

Angle milling a Slant head is something that has been done by a number of engine builders over the years, Gary Bruner is probably the biggest "fan" of angle milling.

I have done angle head milling a few times, mostly to try to get some quench into the combustion chamber. My 209 "low block" engine uses an angle milled head and that works well because the low block is a "zero deck" engine and you can get a flat for quench through angle milling.

Some tips if you want to do this:
-The 1960 to 67 heads are better for getting a flat for quench when you angle mill.
-The head bolt holes should be reworked (angle reamed & spot-face) so the bolts / studs don't bind / bend in the holes
-The intake manifold and carb. mounting surface will tilt and can cause hood clearance issues. A cut can be made on the manifold mounting surface or the engine mounts can be shimmed to level this out.
DD

An angle mill is where you tilt the head surface relative to the milling machine and take more material off on one side of the head (passenger or driver side) than the other. The way to do it is to take off less material on the intake/exh port side, and more on the plug side of the head surface.

You can also angle mill the head bolt hole bosses on the top (rocker) side of the head to make the head bolts hit parallel to the block deck. I did not do this on mine and have had no troubles.

Everyone I know who's done it has had no head bolt problems, although I imagine you could mill at too much of an angle and overstress (bend) the head bolts. The Bruner clan has done several heads with nearly 0" milled on the port side and 0.200" on the plug side with head bolt boss milling as well. They have also coupled this with 0.100" off the block with stock-geometry pistons to give over 12:1 comp. AFAIK, they have had no gasket issues, and I have certainly had none.

I have done one head with 0.080" port/0.180" plug and one 0.100"/0.200" with no bolt boss milling. These give you around a 30-40 cc chamber.

The idea, as Super6 said, is that you generate a better cylinder head chamber shape with more flat area, and you make the angle of the intake/exh flow closer to "straight in/out". If you like, you can angle mill the int/exh manifolds to relevel the carb, but this is a small angle and I didn't bother on mine.

Hope this helps,

Lou

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