500cc SOHC 11/32" Stem Inlet Valves (Sized - 4.590" Length, 1.825" Head)

High quality inlet valves manufactured by G & S Valves - These are 3 lengths/head sizes commonly fitted to 500cc roadgoing International models - Following Head Sizes available (check your original) : 1.735", 1.750" or 1.790" diameter." - Stem length: 4.590" or 4.625" (two relatively common lengths).

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, the- 4.590" is one of the most commonly used, and 4.625" (or within a few thou of that - which can be taken up by the rocker adjuster if your opposing exhaust valve is a few thou different) is also one of the more common lengths.

If you have an original you are looking to replace - then measure that first - 11/32" valve stem diameter and a concave valve head normallly denote an inlet valve. 

The length of your valve is measured most eaily by placing the valve onto a flat surface valve head up, then run a digital caliper from the face of the valve head to the flat surface below.  A few thou difference between inlet and exhaust valve length can easily be adjusted for by the adjustment in the 3 piece rocker adjuster - but when measuring valve lengths (particularly when building an engine from parts) - ideally the length is adjusted so the cambox height allows for the rocker pad to be centralised with the centreline of the valve, when the cam is at approximate half lit.  Sometimes a slight compromise is called for

The head diameter should be measured across the overall diameter.  1.735" was an original standard Norton inlet valve size for SOHC 500cc engines - but 1.750" is a very common replacement - particularly if the valve seats have been re-cut - so it is always useful to measure the outer diameter of the inlet valve seat (particularly after re-cutting), as this will tell you the maxinum valve diameter that will fit your engine.  Remember - if fitting larger valves than were previously fitted - always to plasticine the top of your piston on reassembly - to ensure you have sufficient valve to piston clearance.  I always used to look for a minimum of 60 thou valve clearance when building a race engine.

If you are unsure you can email us for guidance and availability before ordering - on paul.norman@racingvincent.co.uk.