PART NO.  SPL.PAGE  DESCRIPTION                                                           
3H576     15.A.7    Tap -water drain -(engine unit, 1500)
3H576     sup.8     Tap -cylinder drain -(engine unit, sup)
3H576     16.A.2    Tap -cylinder block drain -(engine unit, 1600)
3H576     TC.A.1    Tap -water drain -(cyl.block assy, engine, Twin Cam)

ARH1050   15.C.1    Tap -drain -for radiator block -(cooling system, 1500)
ARH1050   16.C.1    Tap -drain -(for radiator core assy, cooling system, 1600)
ARH1050   TC.C.1    Tap -drain -(cooling system, Twin Cam)

The thread is 1/4-inch BSPP (British Standard Pipe Parallel thread). The standard thread designation is G-1/4. This is a Whitworth form parallel fastening thread, 19 threads per inch, and major diameter is 0.518-in (13.157-mm).


For more information on Petcock Drain Valves see COOL-128