Re: 9.2:1 CR in 327?

Posted by su8overdrive On 2012/7/5 18:39:02

Whew, that's gonna be some honker. Since you live in the land of Autobahn, you might look for a differential out of a non-overdrive Packard to give you longer legs in overdrive.

Old rule of thumb was that, in general, an ohv engine can go a full number higher compression than a flathead without pinging. I agree with the gents above, 9.2 sounds high as a kite, and the above adviso to doublecheck valve clearance is good.
You have to think Packard knew what they were doing when they called it a day at 8.7 to 1. Perhaps you'll make it.
Please keep us posted. 327's are good, husky engines.

We stuck a 327 head on my '47's 356.
Since the 327 came out halfway through the '47 model year so Packard could finally offer a postwar convertible, that model of the '48 bathtub coming out earlier, a 1947 Packard Service Counsellor mentioned using the 327 head on the 356 would give a little more power.

Tho' Packard never wrote anything about using the 288 head on a 356, a friend did so on his '42 160 convertible.
But we figure i'm still a relatively conservative 7.5:1 and he around 8:1.

I wonder if carbon is an issue with modern oils, cleaner gasoline, than when your engine was new or late model.