I always thought when I had my engine rebuilt I could run the engine off the full manifold vac. source for the vac. adv. I actually found from talking with others I am no longer stock and using a aftermarket cam I needed to bump the timing up to 12 BTC and use the ported vac. source for my vac. adv. When I was using the full man. vac. source and she'd run hot like the timing was retarded not knowing that the cam I had needed to be adv. some to get the performance it has to offer, so I left it there and drove it like that for 3 years and went through 2 carb's new and tested 10 others on her to find that it was always a timing issue not the carb's. There has always been a discussion about the pros and cons of using full vac. source and ported sources for vac. adv. and both sides have there good points but I found I was having a problem running full manifold vac. My engine was running hot and sounded like it was loading up at idle, when I bumped the timing up and went to ported the engine had better performance and ran a little cooler, to think I listened to the engine builder and ran stock timing for 3 years and the car after that wouldn't drive 10 miles before having to pull over and let it cool. I also heard about drilling an 1/8" hole in the thermostat, does that really help?
