Piper vernier timing pulleys are an invaluable addition to your performance camshaft as they allow exact timing. The standard pulley for your engine is fine for the standard camshaft but performance camshafts often require different timing which means that unless you fit a vernier pulley you may not be getting the full benefit from your cam.
Manufactured from ultra light Dural material and with an etched graded scale to allow you to quickly advance or retard the cam timing.