While doing routine maintenance and replacing parts that get you stuck (fuel pump, water pump, alternator, hose and belts) I noticed it had a 7 pound cap on it. By the 70s, almost everyone was using 12 to 15 pound caps. No signs of overheating. I've had it for about 3 months and driven it maybe 600 miles so far. Is running a low pressure cap like this ok in the long run?

 

Get a correct 13 lb. cap. It's only about $15 (or less) and then it won't weigh on your mind.

Run it with a 7 lb. cap and "that day" might come to fruition.

 

A lower pressure cap doesn't make it cool any worse - it just takes less overheating to get the coolant boiling.

 

Thanks. I have several NOS 13 pound caps so I'll put one of them on. I don't put Autozone China made stuff on it if I can avoid it.

 

a 7 pound cap is recommended by the radiator shop that cleaned mine.

they said you want a 7 pound cap on a old engine because of head gaskets and seals are old . if the engine gets overheated the light cap will save your engine

makes sense to me. thats what i use.

 

yes I've heard that too and cars til about 1957-58 show a 7 lb cap to be the right one. My 390 has about 20,000 on a rebuild, so think i'll go with the 13.

 

2x... and I avoid Stant caps like the plague. They're hokey.