I need suggestions for a method to reduce spark
advance, when under boost,
(the vacuum 'advance', needs to also retard)
with a non-computer distributor.
I know the are 'electronic' distributors that do this,
but they seem overpriced for what they are.

 

Long time ago somebody made a vacuum advance canister that would also retard under boost (sorta like "negative vacuum advance) instead of just going back to zero and sitting there. As I recall it was made for the old GM points style distributors, but maybe somebody still makes something like this for the HEI.

Alternatively, look into an aftermarket ignition amplifier box that has electronic/adjustable boost retard capabilities (MSD, etc.). If you're running boost you probably want to upgrade the ignition system anyway.

 

I had one of those for an HEI distributor somewhere. Probably best to do it electronically though.

 

Sometimes I see these on ebay for a reasonable price.

http://store.summitracing.com/defaul...&part=MSD-8762

 

look for msd btm box

 

wasn't that on the turbo corvairs (sp)

 

Ditto, both MSD and Accel make auto retarding ignition boxes. Adustable by 1-5* per pound of boost at a maximum of 20*.


~Max

 

I had one on a supercharged small block years ago, that was put on an HEI distributor - I believe it was made by B&M. Unfortunately, since they got rid of all their superchargers and related components, I'm sure it has long since been discontinued.