- High quality inlet valves manufactured by G & S Valves - Following Head Sizes available (check your original) : 1.750" or 1.790" diameter. Standard Model 30\40 stem diameter : 11/32" - Stem length: 4.590".
These valves already have the collet groove machined and are ready to fit. Note: Norton cammy valves were made in a variety of lengths over the years, however, this length - 4.590" is one of the most commonly used. If you have an original then measure that. If you are unsure please email me.