Unknown cylinder head

Your Dommi head with casting number T2225, above the intake rocker cover, was the third version of thetwin cylinder head manufactured by the Norton Factory and became available on road bikes around 1955.

This was the first of the model 88 (500cc) Aluminum heads. It is cosmetically/visually the same as the previous iron head and used the same valve gear and other components.

The Norton head with casting number 22707 His probably a standard 88 or 99 head (not 88SS) from the 1959 to 1963 period. Compared to you other head it should increased finning all over, especially in the exhaust area. The finning pattern in front of the spark plug should all horizontal. Also the inlet valve heads are slightly larger. The 22707 heads were almost identical for both the 88 and 99 engines of that period and had the same mounting positions to take a 2 into carb manifold. Both used the same major components but the 88 had a slightly smaller carb.