Quote:
Originally Posted by David Brown
One of the now defunct Pontiac magazines did a comparison test on #15 heads vs. some other large valve heads. I don't remember the exact large valve heads, but the 15s actually did quite well and had good breathing. The main drawback was the pressed in studs, and even that was only an issue if larger lift cams and heavier springs were used.
I quit using the #15s years ago (80s) because the engine pinged a lot, (even after a total stock rebuild) after they eliminated high octane leaded fuel. Back then, the local expertise about cams to compensate for that was not easy to find. And there was no internet to discuss with other Pontiac people.
|
David, I had my rocker studs pinned like the good old days. With proper cooling, timing curves, jetting and 93 octane fuel, it behaves fairly nicely, except for really hot days (90 and higher) it'll complain when loaded. It needs a better radiator and I have a new Cold Case aluminum to try out in it. It got 17.5+ mpg at 60-65 mph travel on the 2-way state highways driving to Norwalk on its maiden voyage. So that included stop & go driving through the towns adn villages along the way. This motor is in my 70 LeMans 4-dr sedan with an M-20 4-speed and a 3.08 GP 12-bolt (Canadian McKinnon). So it is about 700 lbs less weight to haul around and i'm sure that helps in the stop & go fuel economy.