[Tommy]

I was thinking more about the effect of timing on engine temp and thought of an issue I had with the engine in my Cheetah. You may find this helpful. My engine was built by an alleged race engine builder who was trying to boost his credentials with big HP dyno numbers in spite of my desire for a more street friendly setup. He pulled 600 dyno HP at 6000 RPM from my 427 c.i. engine. As I was trying to make the finished car more streetable, I discovered that the cam it had produced such low vacuum at idle/cruise that is was not feasible to run vacuum advance on the distributor. That meant the timing at cruise was substantially retarded compared to a distributor with operational vacuum advance. Retarded timing is a recipe for excess engine heat because the combustion process is not completed before the exhaust valves open. This reduces fuel efficiency and the late burning transfers a lot of heat to the exhaust valves and other engine components that have to be cooled by the coolant. . . . I did what I could by adjusting the mechanical advance to put in as much as it would stand as early as possible. My setup is tolerable for the conditions where I drive. I don't know how it would be in100 *F and stop-go traffic.