Coolant Tank Cap Rating?

[don hodgdon]

I tried searching but did not come up with a definitive answer.

What is the correct rating for the coolant tank cap? I'm running a 12lb. cap and I think it may be overpressurizing the system. Before I replace it, I'd like to find the correct specs for the cap.

This is for an '85 GTV6

Thanks!

[Balocco211]

Memory serves me, (what remains) (point).7 bar