318 Build

rumblefish360 said

I generalize by stating the advertised ratio drops to low to be an effective ratio for the cam to operate at.

My advice for getting the best you can out of it from where *I think* you stand is to start with removing the 318 heads and measure how far down the piston is exactly. Then cc the 360 heads. Report backnor have a friend/machinist do the math and the required amount to mill the 360 heads down for a 9.0-1 ratio with a 9.5-1 being the max.

Click to expand...

That is where everyone would love for stock 318 LA block/piston owners to be able to go on static CR. But I have worked that challenge out multiple times and the answer is always the the same.

With:
- stock 3.91" bore
- the best stock 318 piston height of about .077" below the LA deck
- .028" thick head gaskets
you come up needing 53 cc chambers to reach 9:1 Static CR. That'll take a mill of somewhere around .100" +/-off of the typical open chambered 360 head of this type. That basically takes all of the 'open area out and leaves the closed chamber shaped part only. That much off seems tough (but I have never tried to have it done). I know /6 heads can take that amount of milling but I am not sure on these. And you would still need to see if the valves would clear the smaller 318 eyebrows. (They may....)

So, I would lean towards keeping the cam smaller and doing the best you can with a not-so-complex mill job (like maybe .050"?).

Or accept the low end dogginess and gear up (like to that 3.91 ratio) and push up the TC stall and work the gas pedal to get around it. Works for the strip; but may not be what is actually desired.