The Stovebolt Site Forums The Shop Area The HiPo Shop Radiator cap...how many pounds

Have set up a early 250 c.i. to look and hopefully run like an early "Vet" 6. I have adapted/installed 4 bbl. carb, "Offy" intake, split exhaust, etc. Have aftermaket hi-dollar radiator. Question...with a "perky" 250, how high of a pressure should I run on the radiator cap? I do have a "puke" tube but don't want antifreeze all over the chrome and polished alumnium. Thanks in advance for your comments.

Hey Beltfed,I would use a plastic tank connected to your overflow tube(what you call a puke tube) and a 14 lb.two way closed system cap.You can hide the plastic tank so only the hose shows.You can get the kit at any good auto parts store.A 14 lb. cap will raise your boiling point with a 50/50 mix of antifreeze to approx 259 degrees and keep the overflow contained.

What about setting an overflow tank inside the frame rail,just behind the core support? That way you can run the overflow hose down to it and people will mostly assume it vents outside,somewhere below the frame.
Speed

How can you tell if you have a 2/way cap? my overflow tank stays dry.

It has a valve(flapper)in the center to let the coolant be sucked back into the radiator as it cools.Should also say closed system on the cap and the pressure it blows off at.

Thanks, I will look today. Like I said, I installed a overflo tank but never even gets damp. Have a 14lb cap on now, aluminum radiator and pump, all good condition should I lower it?

No,I wouldn't with a new system.I have seen some Chrysler systems with a 16 lb cap.Put some coolant in the tank and see if it sucks it back into the radiator after it is run then cools off.

will try as soon as the weather in michigan permits. thanks

p.s. I do have a 2 way cap but will be unable to fire the thing this week.

Don't forget the heater core. Early heaters were only made for 2LB presure and even a later used heater won't take a lot of presure.

Good point Lugnut!You are right about that.