Edelbrock Performer RPM (7577) and 360 Magnum CI heads

Coolant ports

ALL American SB's that I can recall are made this way, Ford, GM, Mopar. They are made this way because the heads are reversible side to side, and therefore must be non "left or right."

Actually some racers add fittings to the rear ports and hook hoses in to increase coolant. Who knows if it really helps except in extreme HP cases