glasman, I think I did not make myself clear. I am suggesting that his centrifugal advance is not working...either broken springs or what have you. Whenever he sets his initial timing everything will be ok. However as he revs up the engine, it will not advance, and if the vacuum is working, it will retard it even more and it will run like crap. I have seen this quite often. In fact a lot of people don't realize they have an advance mechanism under the breaker plate. The effect is very similar to what used to happen when someone used a carb from a load o matic Y-block and put a 57 or later distributor in it. Also if his distributor he is using came from a larger truck, it will have been designed to be used without a vacuum. It wasn't uncommon for people to put a vacuum changer on them just because there was a line to the carb and they thought it needed one. It is difficult to say what all has been done to a 60 year old truck that doesn't have the original engine.