The bypass is to permit water flow around the closed thermostat between the
pump and the block allowing the block to come to temp as quickly as possible.
This is a good thing by the way. Once the water temp reaches the thermostat
temp opening range, then the properly heated water will pass through the
radiator for heat exchange before returning to the block.
As Theo has described, I have the blocked off bypass and a drilled high flow
thermostat in both my street Tiger and Mustang as well as my open track cars.
My street Mustang run too cool as it rarely even reaches 180 degrees with
normal driving. I will replace it with a 195.
This bypass technique will result in a longer heat up time. You want to get
your water and oil up to operating temps prior to loading your engine.
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