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Old 07-08-2020, 06:23 PM   #18
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Join Date: Jun 2010
Location: San Antonio, Texas
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Default Re: Bending Overflow Tube

The model A was designed to run with no pressure but it did have a water pump. This was an improvement over the model T with thermosiphon technology but not by a lot since the model T could only pull so much anyway.

It's all about extremes when folks want to add pressure to the system. On very hot days where the car has to go up long steep grades is where the pressure is an advantage even if small. The car will recover after it crests the hill but it has to make it up there first. The coolant generally won't get hot enough to boil unless the engine is under stress or there is something wrong with the cooling system or too much friction in the drive system.

Ford added 4-psi caps after WWII and the 7-PSI caps came along as the cars got even heavier in the early 50s but were still using 1930s technology. With larger engines and air conditioning thrown into the mix, they went up to 14-PSI.
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