Milling 318 Heads to raise CR

1974DartSwinger said

My 318 is rated at 8.5:1 from the factory. I've been told the actual compression was closer to 8.0:1. I'm just going to cc the heads today and see what I'm actually at. So I'm going to be safe milling 30 thous without worrying about the top end going boom? Hmmm, maybe I'll mill 50 thous and use the 30 thous rocker post shims from Mancini's. . . . I just want to get my ratio up to a solid 9.0:1 actual compression or its going to run bad with my comp 268 cam.

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I would just put a thin gasket on it and call it bueno. The compression is not too bad, if just left as is. I am running a Comp XE268 with stock heads with a 3 angle, close to stock thickness gaskets, Hooker headers, Holley 650, and a tall K&N 4" air cleaner with stock (for now converter), and 3.21 gears. It is a bit soft launching hard out of the hole below 2,000, because of the stock converter, but pulls very hard for a 318 above that. Around town, it has great low end power and behaves well, even though the cam will have a light to moderate lope. Its a good sounding motor as well. I shouldnt have an issue running in the mid 14s with this at all, which is good for a hwy geared cruiser.

With your converter, it should run even better, plus being basically stock internally, besides the cam, the 318 should last forever and take lots of abuse, with proper maintanance.