Adjustable.
Engine Distributor Vacuum Advance Canister
Fits GM HEI Models 1996 and Earlier
Will Not Work With Computer Controlled HEI Distributors
Adjustable Style Allows User To Fine-Tune The Vacuum Advance For Optimum…
This unit permits a seamless wide range of adjustment to both amount and rate of ignition advance. This unit helps increase horsepower and throttle response. It provides maximum spark advance while preventing detonation or "pinging"…