Why is it so hard to get good advice !!???
If you have .056 now you do not have any real quench now. Because the quench is not there I would lower the dynamic to below 8:1. It will make more power overall with the larger cam, so don;t sweat it. Just change the cam.
Wouldn't there be
some quench even at this number?
I have talked to people at Hensley Performance, Comp cams, Mancini Racing and all of them have offered advice opposite to what I have read on several web forums. This is what they had to say:
Hensley: "
You need a thicker head gasket to lower the compression and a smaller camshaft."
Comp Cams: "
The '509 cam should be just fine. I wouldn't change it. You just need a thicker head gasket to lower the compression."
Mancini: "
A thicker head gasket, something like a Cometic MLS would lower the compression enough to run on 91 octane. I'd do that along with using the 1.6 ratio rocker arms to give your cam more lift."
See what I am dealing with?
For the record, even with my lack of experience, I agree with the following:
Quench helps an engine make more power by allowing it to run more static compression without detonation.
An engine with over 190 cranking compression will not run to its potential on 91 octane fuel.
Long stroke, big displacement engines can tolerate a more radical cam than a stock stroke 383/400/440.
In 2006 I tried the combination of a .060 Cometic head gasket and a Comp XE285HL cam. The car ran great but I never drove it hard enough to determine the detonation condition. It wiped a lobe within a few weeks. I tried another cam and it also failed. I felt burned by what I thought was defective Comp cams products, so I reinstalled the MP '509 with new lifters.
