For Chevrolet Small Block V8, 90 degree V6 and 4 Cyl., and Ford 4.6L
1.255 inch ID with 3/16 inch Keyway
Specially designed 1/2 inch drive socket allows rotation of engine assembly
Knurled retaining nut that holds degree wheel in place
Can be loosened while on crank snout so that wheel can be turned independent of the engine when finding TDC