What lb radiator cap 347 sbf

[Daryl]

Was sent their accompanying 19lb cap when I bought the Mishimoto aluminum radiator but as I’m spitballing possible reasons I: (1) had a little trickle leak after running it harder than usual; and (2) fluid cold always drops down to the bottom of the filer neck?? Where does it go, the overflow tank? Level seems the same there as always.
I Goggled “what lb radiator cap for 347 SBF” and it came up 13-16lb cap. Is 13-16 correct for a METAL rad and 19lb for aluminum?

 

[96blak54]

Good question! I would have simply unknowingly used 13-16lb cap, but now i question.

 

[Mustang5L5]

I run a 16lb cap.

The only advantage to running a 19lb cap is you raise the boiling point of the coolant. With a 16lb it's around 270 degrees. With a 19lb it's around 280 degrees.

The downside is higher system pressure, and increased stress on seals and such.