Mike B, I have heard of that situation but have not personally experienced it. The water pump will move A LOT of volume when unrestricted. Probably the same is true in the water jacket around the cylinders and head/s, if the water is moving too fast it may not be able to transfer the heat from the iron to the water.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
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