In summary, the 10.7 CR detonated on 91 octane when I had the MP 292/509 cam. I changed to 1.6 rocker arms, bumping the lift to .543 and while it ran a bit smoother, it still knocked. I added 110 Sunoco to a half tank of 91 and the knocking stopped. All along I have wanted to be able to run this engine on 91 octane or less. I asked questions here and elsewhere about what options there are to get there. I took the advice of a guy on another site on the Lunati solid cam I have in the car now. Well, that cam looked great on paper but somehow made things worse. I can still get it to stop knocking with 110 fuel, but that still leaves me miles away from the original goal. I have tried UPjetting and DOWNjetting the carburetor. I have tried another carburetor. I have tried timing adjustments, different distributors, colder spark plugs, new wires, early day (For cooler weather) and the car still knocks at WOT with anything less than the current mix of 110 and 95 octane fuel. I did change the advance springs in the distributor, but all that did was delay the advance by about 400 rpms. Thats not enough to help. I do not know if the block decks are square. That is an interesting point. I suppose that it is possible to have one or more pistons sitting higher or lower than #1 at TDC. I do know that with #1 piston .017 in the hole and with the .039 head gasket, I am at .056 for quench. I've asked it before and most people seem to think that at that distance, the beneficial effects of quench are minimal if any. It is because of this that I have considered using the thicker head gaskets again. Regarding the possibility of getting a bad batch of gas or gas labled as 91 that is really 87: I thought of that, but the car has been pretty consistant. I live in Northern CA and have driven the car to LA and back 3 times. I have been dealing with this same problem for years. It is just this year that I have had some $$$ to spend to fix it.
The valley pan has been clean and dry since I replaced it a few weeks back. Looking back at my notes, I found that when replacing the valley pan in the past, I have alternated between using the tin alone as well as using the paper gaskets. I'm embarrassed to admit though that I had the intake manifold torque spec way off. I was only cranking it to just past 12 lbs because I incorrectly thought I read that in the Edelbrock instructions. This engine has no blowby. The cranking compression numbers are within 4% from highest to lowest. It got closer when I put in the adjustable rockers, probably because the stock type rockers were inaccurate.
