for a 53 Ford 2dr. with a stock flathead (mild hop up) with stock radiator? it seems to ge hot pretty quick. it gets up to 200 degrees with 20 minutes of driving. also has a 160 t-stat. the radiator has a 7lb cap right now. is 7lb to small?
May be time to check the timing. If you have the stock dizzy as the fibre shoe on the points wears it retards the timing that can contribute to running hot. Also check your advance. Also is your gauge accurate? Verify with a laser infared heat gun. I wouldn't put any higher pressure cap on it.
you can also yank both or 1 thermostat, boil some water up to 160... see if they open, cheaper than a laser heat gun. check for retarded timing as described.
7 lbs is good, check timing as said. flatties like to run warm...customers '51 woody wagon runs about 170-180 at night and close to 200 in daytime (it has 160's in it, the block is clean, timings on, rebuilt dizzy and it's running a 7lb cap).
ill run a bit over 200 if im chugging up a hill... otherwise 170-180 is the norm.. it once hit well over 210... and survived,
alls the pressure is doing for you is raising the boiling point of the coolant. If I remember right it is 2.75 degrees per pound of pressure. So a 7 lbs cap will raise the boiling point of water to about 232 but since you have a coolant in there it will be higher depending on the blend
be carefull with a higher pressure cap on an old radiator. The tanks on old radiators are real big (lots of surface area), and with a high pressure (13 to 16 psi) cap you will bulge or blow out the tanks... 7 psi should be fine, likely the block is full of ****, contributing to it running warm. If it does not boil the coolant, you're fine.
when the car is shut off after driving around for a bit. i raise the hood and i can hear sizziling sounds come from the radiator. the motor was rebuilt a few yrs ago and the radiator was also freshend up. so it can be time to check the dizzy and water pumps?
also buy your cap from a radiator store and get them to pressure check it first. just because it says 7lbs doesnt mean it is, but seems we all expect that it is. I just bought a new 13 lb cap for my new radiator for the motor, run 160 thermostats, the old radiator use to sit on 160 when on the highway and cool nights. the new radiator and cap was 170-180. after a drive during the night it was sitting at 170-80 I took the cap off the next morning, and it made a noise like cracking a beer, never heard this before??? why would it still be pressurised? so I put the old cap back on. warmish day 70-80 f and the car now at highway runs dead on 160! so dont always trust the cap!!! and this is a 4/71 blown flathead too.( hence the new radiator)
Add 1oz of water wetter or purple ice for each quart of coolant you have and this should lower the temp a few degrees. Redline makes the water wetter and royal purple makes the purple ice.
I had a post a few weeks ago about my 54 chevy running hot and some one said to check and make sure the new radiator cap fits correctly on the old radiator, as in the neck of the radiator might be longer than the spring and seal on the new cap, just an idea.if you want to check out my old thread to see exactly what the guy said. good luck
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