[bobH]

Ummm... We don't exactly know what your driving conditions are. Hills? Flat? Speed? So, I'll offer this opinion and experience... I have a 36LB in a 34 sedan. With 3.78 axle, which is the same as many Model A's. And, I have one of Skip's pressure valves on the radiator overflow. If I drive on the flat, and don't push it beyond 45, it doesn't boil or push water out. (No temp gage) If I push it, it wants to throw water out the overflow, and it wants to heat up, sometimes to boil. I live in the mountains, and almost any driving involves going from 6000 ft elevation, to less than 1000. And, back up. So on a hot day (easily 100+ at the base of the hill), it's quite a challenge to drive up the hill to home. Back in the day, when I was a little guy and my parents did the driving, they never did the hill, mid-day. Always early AM, or well after dark at night. So, what I'm saying, these old cars, even when new, had heating issues. And, whatever make, not just Fords. So, to drive up the hill during warm weather, I count on a few stops to add water. Just the same as what my parents did 70 years ago. On the other hand, when driving flatland, and holding to 45 or less, I can go hours without adding water. Obviously, just opinion and my experience. (and, I have run with, and without thermostats.)