Radiator cap pressure rating

[shadango]

The cap on my radiator is a 9lb unit. Its one that came on the radiator I bought for my fish.   

I went out and bought a new rad cap...the lever-lock kind by stant.....but the book listed a 16lb cap as the proper one.

Am I safe to use a 16lb cap or should I keep using the 9lb cap?  The engine runs at 180 or less (according to my summit gauge) and at the bottom of the range on the stock temp gauge....

If it wasa lb or 3 off, thats one thing...but jumping 7lbs?   

What size cap do you guys use?

Thanks folks!

[Chryco Psycho]

typically they are 13-16 lbs , that should be fine

[shadango]

Does the a higher poundage actually help it run cooler or just keep it from boiling ?

[GoodysGotaCuda]

Does the a higher poundage actually help it run cooler or just keep it from boiling ?

Raises the boiling point by 3* every PSI you go up (if i remember right)

[shadango]

And that is a good thing internally to the engine......right?

Is it worth going from the 9 to the 16? What will it buy me?

I have what appears to be a new radiator , new hoses and such so I should be good to go...unless the old heater core cant take it.....it doesnt leak now, but....

[HP2]

If you ever run it hot, it buys you that much more time before it will boil over.

That also means you putting that much more pressure into the entire system. That can expose weak seams, bad solder joints, soft hoses, etc.

I don't see it as a big deal as most of the cars use a 14# cap. I'm a bit suprised that it would come with a 9# on it. FWIW, I use 20-22# caps on my hot rods. My more stock oriented cars have 14-16 pounders.

[shadango]

The cap I was using was just a cap that was on the radiator when I got it....the rad was installed in an AAR (supposedly) and is a new replacement/aftermarket 26" unit.....I was just running the 9lb cap til I got the engine up and running etc.....figured it was wrong....

I put the 16lb cap on last night and ran it a bit........seems like everything held fine. SO far at least...LOL