anyone know of any pages or sites with info about advance weights and springs and how to kow whats what and how to select which to use ??


i need to find out what the stamped number on the plate and weights mean exactly ? i want ot put the heaviest weights on that i can, and also need to find out about the springs, i have some that are only four winds and some are five, need to know which are weaker and which are stronger


thanks for anything

 

I just looked Friday at some sites I found through the C3 corvette disscusion boards on recurving the dist. I can't seem to find them because they were in linked to a pontiac tech place. Bottom line is to use a timing light to set your max total advance first and then work back to idle.You can mix and match springs around ie. one light and one heavy. The tech article also showed how to fle down the plate to bring in advance faster. Sorry if this was no help ...the # for sprins and weights have to be listed somewhere... I am just having fun changing the curve now that I've lost the computer.

 

cool, i found one page where it shows to flip the plate upside down and file the forward(clockswise) sides of the ends flatter and longer, but said to use a plate number that i dont have all i can find are 368 plates

wonder what the difference is between the plates ?? weight ? length ? post holes positions ? ?

i still have yet to find out what the numbers on plates and weights even means,..

hopefully it has to do with weight ! no one seems to know much about this at all


thanks

 

Whatever the factory did, is completely inscrutable. AFAIK the numbers they put on things are just part # suffixes, with no connection to any physical property of the part.

There is a dizzying variety of those parts out there. Every model of engine in every different model of car got a different distributor part #; the differences between the distributors include cams, springs, weights, vacuum advance cams, reluctor plates (different length slots), and on and on. The advice you get about "just go to the junkyard and get one and put a kit in it" results in a totally unpredictable combination as a result.

The shape of the weight cam controls the shape of the advance curve; i.e., does it come in very steeply at low RPMs and mellow out as it nears its full-in RPM, or the other way around, or is it more linear; the amount of final centrifugal advance - some distributors give as little as 10° of centrifugal, some as much as 28°; the amount and calibration and response speed of the vacuum advance; and various other fine-tuning properties.

It rarely works to turn the cam upside down; the 2 surfaces that doing that would expose to the weights to work against are usually not shaped even remotely near right for a realistic advance curve. That kind of advice is typical Internet BS, about like turning your stock air cleaner lid upside-down. Has about the same kind of effect.... you go backwards.

If you really want to dial in a distributor, make yourself a fixture to spin it using a drill or something and a lamp dimmer, and file the cams (or make them) until you come up with the curve you want. This is one of the areas where the "mystery" differences between supposedly identical engines comes from, and the differences it produces can be HUGE. I know of no way however to come up with a listing of that sort of thing; the only person I know who would even possibly have had such a thing passed away a couple of years ago (Kelly Davis, who later started Performance Distributors in Memphis), and I don't know if his son would tell you.