Radiator psi

Flathead fords, whats the common psi of the radiator .The rad.shop guy laughed when I said its about 6#s

 

Dude,build a good rad and reap the advantages of physics...for every pound you pressurize your coolant you raise the boiling point 3 degrees.....Build a rad to hold at least 17 to 19 lbs. of pressure and look at how high the boiling point of the coolant goes up...

 

if your using the original tanks need to stay low psi, i wouldn't go mor than 7 psi and use a recovery tank, this way it will keep the radiator full, remember original tanks aren't made to take high psi

 

I've had luck with 4-7pound caps in the past with original radiators. Much more than that and I've stayed busy soldering holes.

 

The common PSI for flatheads is zero. Ford radiator caps weren't pressurized. I've never found it necessary to pressurize an early Ford radiator. My stock Deuce radiator cools my 255 Merc just fine. It still uses the original style chrome radiator cap through the grill shell. I really don't want to run above 200 degrees so I don't need the pressure. The pressure will let you run those temps with out boiling over but I prefer to keep mine between 180-200. Pressurizing it would be a waste of money for me. Pressurizing won't make it run cooler...it just lets you run hotter.

I've run 283 and 305s on non-pressurized 34 and 36 Ford radiators with no problems.