How much psi should rad cap hold

We're testing to see the psi the cap holds how much psi should it be at

the book says 16-19 psi (1.1-1.3 bar), should hold for ten seconds...

i got a rad cap from auto zone that is 1.1 it fit on my radiator will this work till my new cap comes in?

I've heard a couple horror stories about aftermarket rad caps...though not with our bike.

It was the beginning, of the end, for my bros toyota pickup...eventually blowing head gasket.
He really wishes he just got a factory cap to start with.

Anywho, maybe just bad luck....but I will only use a factory cap if needed.