We just had a big discussion on it in the troubleshooting section.
Take a look there on "big block vac advance problem"
You need to limit your total amount of centrifical advance.
If you set static at 10 degrees, you need about 26 degrees of advance in the distributor so the total advance comes to 36 ot 38 degrees. 10+26=36
IgnitionMan would have better numbers than I list here, this is just an example and fairly close.
Most stock distributors have more advance built into them than that.
Distributor advance is limited by a pin on the bottom of the advance mechanism that fits into a slot on the breaker cam piece.
There is usually a plastic bushing or rubber bushing (older point dist) over the pin from the factory.
Often they come off with age and high rpm's and allow the distributor to advance even more than intended.
The breaker cam slot ( on a HEI it's called something else but functions the same) has different length slots depending on the engine and application, which limits total advance degrees.
Most aftermarket kits have a bushing that goes over the pin but you may have a long slot in your cam that gives too much total advance.
Get it reworked by someone like IgnitionMan, he's got it all handled. He can even make a small body HEI out of a stock distributor.
You need to learn how to set for total advance timing with a timing tape if you don't allready.
Check my web page for suspension info:
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer
[This message has been edited by davidpozzi (edited 07-29-2000).]