My 1935 has a 21 stud engine with the water pumps on the end of the heads. The pumps push coolant to the top of the radiator. My question is with regards to the newer flatheads that have the water pumps on the bottom legs near the lower rad hoses. Is the direction of coolant flow the same through the engine and radiator in all flatheads? Thanks, Gary C
Coolant flow direction
- Thread starter Gary C
- Start date
JM 35 Sedan
Well-known member
The pump in block design moves coolant in the same direction but does a more efficient job of cooling the engine than the earlier pump in head design.
JM, I don't think the block mounted pumps are that much better than the head mounted pumps. Skips modified head pumps deliver 92 gallons each in 5 minutes which is better than a stock block pump. Every pump he does is tested for at least 5 minutes on a water pump test machine so we know exactly what is going on. A stock 37 to 48 block pump delivers 65 gallons in 5 minutes, a stock head pump does 55 gallons in 5 minutes. The turbine impeller in the modified body of the block pump delivers 110 gallons in 5 minutes. One condition is most block pumps were used on radiators with a pressure cap where the head pumps had a vented top tank on the radiator. The radiator tubes are restrictors and the water don't free flow through the radiator and for good cooling the water needs to be forced through the radiator. The pressure cap allow forcing the water. On a vented early radiator which is the over flow tube the water can not be forced through the radiator and due to the radiator tube restrictions a large amount of water is lost from the cooling system out through the over flow tube. The 22 quart system now has lost a gallon to a gallon and a half of water. This low water causes the engine to run hotter. A 3 lb pressure relief valve is available for the bottom end of the over flow tube on these early radiators without a pressure cap. This allows the water to be forced through the radiator without going out the over flow resulting in better cooling and no lose of water for months. This valve is like any other mechanical device and needs to be flushed out with fresh water once a year or perhaps sooner if the cooling system is dirty. More water flowing through the system and more water in the system provides better cooling. G.M.