73 Duster 318 seems to be running pretty hot

[TF360]

Put a new water pump on it while you are there and everything is apart-they are cheap

 

[68gtxman]

Keep in mind that the radiator cap allows pressure to build in your cooling system and per Boyle's Law, PV=nrt all other things remaining the same, a higher pressure will prevent the coolant from boiling at lower temperatures. Said another way, the higher pressure raises the boiling point of the fluid. So if water boils at 212 F at atmospheric pressure (I.e. cap off) with the cap on and pressure built up, water would boil at a higher temperature (240 F hypothetically). Then the larger the temperature difference (called "delta T") the faster the heat transfer will be through the radiator.

Mopar used a 16 psi cap IIRC, so if you have a lower pressure cap, then you have lost some cooling capacity from your system.

 

[Trevor B]

Well Folks,

Thank you all so much for your tips and advice.
Attached is a picture of the old core, which is about 90% clogged!

Got the rad back in with a brand new core and the coolant is circulating just fine.
My test drive was a success - the needle barely moves above the low mark. I'll put the thermostat in tomorrow.

(I didn't replace the water pump - it feels good and solid to my hand; the rad cap is 16 lb)

On to the next thing(s).

 

[Inertia]

Right On ! ! ..

now for lotsa miles with lotsa smiles..

cheers