[Cobranut]

BJ,

I don't know what engine your running in the 40, or how radical it is, so I'm doing a lot of speculating here.

My 427 has 12.5/1 comp and a fairly radical cam. When I broke in the cam, it wanted to heat up. I kept it cool with a water spray over the radiator until I discovered the cause, insufficient initial ignition advance.

I now run 21 to 23 deg initial advance, and limit the total to about 40 deg. I had to make a bushing for the distributor to get this curve.

In 90 deg + weather, with a 180 deg thermostat, I never see over about 190 or so. Sitting in traffic, the fans still cycle on and off as the t-stat opens and closes, so I'd say I still have extra cooling capacity. Even on a hard run up the mountain, or on the track, I never see over 200.

What happens with late timing is a lot more of the mixture is still burning as it goes out the exhaust ports. This transfers a lot more heat to the water jackets, and less of it is converted into torque.

Tell us a little more about the combination, and let me know if this helps.

Good luck,