289 heads
 

I have a 66 289+040 and I also have a set of 69 351 heads I want to put on it. I know about bolt hole differences and got that covered,My question is how much can I mill the 351 heads safely and can they ( yes I know its a chevy trick) be angle milled for any gain. the engine has flatops ib it and what the guy calls a 3/4 cam( it was built a few years ago)

Every time some one I know tryed Angle milling heads there was some nasty concequences.

The motors seemed to love destroying Pushrods. Also gotta be carefull when you start angleling heads, you might run into some sealing problems with the Intakes, especially if you shaved them a good bit then Angled.

OK so angle milling is out. These are supposed to be 60cc heads and the 289s are supposed to be 54cc can the 351s be milled .030 and how many ccs will be removed I'm trying to keep up my compression ratio

Milling the heads to true them up and clean the surface is common practice. But angle milling them is somewhat risky and best left to those with real knowledge of how to do it.

I got a little happy at the milling machine at College and gave myself a little more compression than I wanted. With the cam I have I think my compression is a "Little" to high. Actually I think the machine was off also. I wanted 10.5:1 and I got damn close to 11:1.

With the larger combustion chamber, the best way to keep vavle clearance and gain compression is to get domed pistions. They can be pricey though.

I never dynoed or raced my old Stang at the track but she Hums along pretty good, and she has Stock 289 close chamber heads that I spent alot of time porting and polishing.

From what I've heard from my machine shop guru, 351W heads can be angle milled up to .050 without doing anything to the intake manifold or encountering valve train geometry problems. Not sure how much my 351W heads were milled (the block was decked .010 also) to give 9.5/1 CR with flat top pistons. BTW, flat top pistons are supposedly better if you can still get the CR you want because flame propagation is supposed the be better.

Rev