Small block Chevy cylinder heads come in lots of configurations. Heads with accessory holes are from 1969 and later and any head with a double Humps are popular. An example of pre accessory hole double hump heads are “462” but these 1969 heads are “186”. For 300hp engines, they had 1.94 and 1.50 inch valves. For high performance engines, the 186 heads had 2.02 and 1.60 valves. #chevrolet #classiccars #chevy
