Shouldn't require any machining to get it to work. There is a matching roller button that is also available. The cover comes with an adjustable TDC pointer which helps solve a common issue and the center plate can be used to adjust the cam installed centerline if you use a hex-a-just type chain. The billet cover has an extra thick gasket mating surface which reduces or eliminates leaks and it fits under a stock type water pump housing. There is also a setup plate included with the cover that provides the engine builder with a simple way to measure camshaft end play.