Restrictor washer instead of t-stat

[G.M.]

Henry you have Skips information correct but the pressure valve is 3 lbs. It also is NOT INTENDED to increase the boiling point. Increaseing the boiling point is not a factor on the old Fords. Properly cooled the coolant temperature will never get to 212 degrees. The 3 lb valve or 4 lb pressure will release the pressure just before the coolant boils. When the coolant gets to 200 your close to having problems. The idea is to never let it get over 200 and if you get in heavy traffic with one of these cars with a boarder line performing fan you have to get moveing so the forced air cools the coolant. With a 4 lb pressure cap or the 3 lb valve and high volume water pumps the temperature will come back in the normal in about 1 mile. G.M.