Join Date: Mar 2002
Location: Austin, TX, USA
If it were a GM HEI distributor I'd tell you to inspect the weight bushings. Perhaps the Accell has the same issue. The bushing wear out and the weights can advance the mechanism too far. If that all looks good, then you'll have to limit the advance somehow. Some weight kits might help. I've known guys to drill them and install a stop to prevent over advancing.
You can measure the advance on the workbench. Use a protractor. Clamp the gear end lightly in a vice. Then rotate the advance mechanism by hand and measure the advance. Remember that one degree of distributor rotation is 2 degrees at the crank.
Rules of thumb are 10* base and 36* total. So the total advance should be around 25* or so. But that is only 12.5 degrees of distributor offset.
Does your distributor have a port for vacuum advance? For one, vacuum advance is a good idea. But alternatively, you may be able to get an advance limiter that uses the vacuum advance blocking plate. It uses a cam to limit the total advance. Check out Accell's web site.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI