Quote:
Originally Posted by holdover
Exhaust valves (for reasons mentioned above) are usually smaller than intake valves. Increasing valve size does not always increase flow, depending on the engine/head design it sometimes reduces flow across the whole valve lift. An example is the 305 Chevy engine, increasing intake size alone often reduces flow, there is a delicate balance between value size, lift, porting, intake and headers etc.
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Don't overlook the fact that the 305 has smaller cylinder bores, thus shrouding the intake valves.