318 Build

toolmanmike said

I haven't read through this whole thread yet but aren't the open chambered 360 heads going backwards? Wouldn't #302 or a closed chamber 273 head be easier to build compression and quench? I think porting small chamber heads is a better idea than milling open chamber heads to get your 9-1 ratio. You mill the heads and the intake won't fit without milling and the two will always have to be used together.

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I was just trying to run with the idea of the OP to use the 308 heads and get the benefit of the better flow of those, since that is what he wanted to do initially. I actually find the idea intriguing, of milling the snot out of some 308's and putting them on a stock 318; there are all sorts of guys wanting to use their 318 short blocks and do what the OP wants.

Milling .090"-.100" from the 308's may be doable. I have read of guys milling that much off of the open chamber heads and it basically takes all of the shallow 'open' section of the open chamber completely out of the head. You still would not get quench.

If it worked, you take out 1 cc of head displacement for something like every .0055" of milling. Then would end up with a TRUE SCR of around 9.1 or 9.2. That is a good step up for the stock 318. You are now where you can hit the upper 7's for DCR with a decent range of cams, and much easier wheel spinning will result. Now you have come quite a ways out of the low compression/big cam non-performance corner.

I am not sure I would not care if the intake and heads had to stay together forever if it worked. An intake is a lot cheaper than a complete 318 bottom end rebuild. (Though that rebuild resets the engine wear to new....)

Edit to add: Oh yeah, I keep forgetting that the pushrods need to be shortened with this much milling....