C2 distributor advance curve

[Timothy B.]

I am helping a friend set the distributor advance curve on a 1967 L 79, the car has a five speed with a 370 posi and he has installed a comp cam 280. I would like to quicken the advance curve to the 64/65 SHP specs, limit centrifugal to 24 degrees and set initial at 14. I plan on installing a #524 weight base and not using his original #530 weight base, will this be OK because the #524 came from a pass car distributor and the slot is limited to +- 24 degrees?

This is the curve I have come up with that I think will work best,

0 @ 800 5 @ 1000 1800 @ 1500 22 @ 2000 23/24 @ 2500 I also have two more slower curves picked out if this is two aggressive.

I have installed a new NAPA VC 1810 and it checks out at 0 @4" and with a new rubber stop 16 @ 8". Without the rubber stop it advances to about 19 degrees. All thoughts are appreciated, Tim Barbieri

[Duke W.]

Re: C2 distributor advance curve

That will probably work. The limitation on the rate of centrifugal advance is detonation, which depends on compression ratio and the point that the inlet valve closes, which along with static CR determines dynamic CR.

It's a matter of experimentation. Start with such an aggressive curve, and if it detonates at low revs, slow it down. If it detonates at high revs, you will have to reduce total WOT timing by cutting back the initial advance a few degrees.

Since the propensity to detonate increases with increasing inlet air temperature, the worst case is usually a hot summer day.

Duke

[Timothy B.]

Re: C2 distributor advance curve

Thanks for responding Duke, the Mr Gasket springs seem to be very agressive at the low RPM's but I have plotted out two more curves a little slower. This distributor also has wear in the housing where the tach gear thrust is and I can't seem to find a source for the bronze button, High Tech Innovations in Florida is going out of business. I have a GM plastic button and am wondering if someone can tell me the drill size to drill the distributor if I go this route. Thanks, Tim Barbieri

[William C.]

Re: C2 distributor advance curve

Corvette Central had brass buttons, need to drill a small hole (not all the way thru the housing) and eliminate the washer behind the gear (between the gear and the screw in bushing the shaft runs in) to make it work out correctly as the ones I have used are too thick otherwise, and will bund the gear.

[William C.]

Re: C2 distributor advance curve

I believe Bair's also has a kit that may have a thinner thrust surface.

[Christopher R.]

Re: C2 distributor advance curve

1. Hi Tech Innovations is going out of business? Any recommendations for somebody who can install distributor bushings and align bore them?

2. Who is Bair's?

[William C.]

Re: C2 distributor advance curve

Bair's Corvettes, Linesville PA (814) 683 4223, in Business since 1970, always at Fla meet in Jan.