Distributor Vacuum Advance?

vac advance is a gas milage thing, it's only relevant at cruise.


as soon as you accelerate and really load the engine... it's gone and all on mechanical advance.

because the vac advance cannot fall off/disengage fast enough, on high compression/boarder line pump gas compression you may hear a momentary cack/ping upon stomping on it from a cruise. If it was computer [instantly] controlled we could maybe avoid this.

carefully pay attention to the heat range of the plug, with 46-52* of timing you may over heat a plug thats already the hottest the mechanical advance/compression will handle w/o vac adv hooked up.