Welcome to the Ford Barn, I like the testing you are doing, particularly the thermometer in the radiator.
Several questions to help us help you:
- Have you had this car run cool before, and now it is getting hot? If yes, what was changed?
- How are you determining TDC? The stock 8BA timing cover and crank pulley have a pointer and bump respectively, but they are not at TDC (4 BTDC if I remember correctly)
- Have you tried running the car with a stock intake, carburetor, and distributor? I like a stock engine baseline to verify everything is working correctly before making changes that affect tune and cooling. A few years back I worked on a club member's 8BA equipped with a Stromberg 97 and modern Mallory distributor that ran warm, we solved that by installing a correct 8BA carburetor and distributor set at proper timing.
- Where in Texas are you? Several of us here live in various parts of Texas and have experience with flatheads and 100+ F conditions. I find a good 8BA will run 80-90 F over ambient so your car is definitely running hotter than it should. I also prefer 180 F thermostats in 8BA engines (I use 160 stats in pre-war engines in south Texas).
- Not a question just an opinion, I also prefer not to exceed 7 psi cap on an 8BA. I don't see any reason to add pressure to the water pumps and radiator.
- When you run the engine with the radiator cap off do you see bubbles in the coolant? If yes, those could be exhaust gases from a leaking head gasket or a crack and no radiator that fits into a car will keep an engine doing that cool.
I see you have posted pictures in an
album including a few where you were cleaning the cooling passages. I don't recognize the distributor, but maybe someone else on here will.