word for word from the fel pro instructions.
coolant flow.
most head gasket failures occur between the center cylinders because of excessive heat due to back to back exhaust valves. to correct this situation, more coolant flow must be provided to this area. This can be accomplished through the use of a more efficient pump, higher pump speed, restricting the coolant out of the engine ( increases jacket pressure) or revising the coolant holes in the castings and/or gaskets. REMEMBER to make only one change ata time so the effect of a change can be determined.
Note: Edelbrock is one manufacturer who has introduced a new series of pumps with improved coolant efficiency. Also, electric water pumps generally do not flow enough coolant to remove the heat produced by the engine