Making power out of the 318

66fs said

That is incorrect. 69 and 70 351 Windsor heads had the smaller chambers and 1.84 intake valves and larger ports. We used head studs with hardened washers, no problem. Not sure when the small valve 351W went to small ports and valves, nor did I care.

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When Ford went to the small valve heads on the 351 it was a light bulb burned out moment of the bean counters calling the shots. Cost cutting road apples where by they just used the same castings used on the 302 engines. Now in the casting process the cost of 302 or 351 ports would be identical if they all used them. The cost of 1.78 valves would be the same as the 1.84 valves. Now suppose the engineers were presented the choice to use the 351 ports and valves on the 302 engines. I think the engineers would have chosen the 351 ports and valves.
Because emissions cams were ground with retarded timing required lower compression to prevent detonation and NOX. Those were the days my friend, but unfortunately not fondly remembered.