Pro-Comp Motorsports Adjustable Vacuum Advance

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Pro-Comp Motorsports Adjustable Vacuum Advance for HEI replaces your OE non-adjustable unit. Allows you to change the amount of ignition vacuum advance for maximum performance while preventing detonation. Increases throttle response and horsepower while improving performance and fuel economy. Includes 3/32" Allen wrench and easy-to-follow instructions