I was told that the opening pressure for exhaust valves should be around 23 psi and mine are in the 5 to 10 psi range. Should the valves open at the 23 psi? Are the intake valves the same pressure when opening? I couldn't find any info anywhere on that topic. Thanks.

Hi kingmike,
scan below should get you there.
If your valves are pocketed in--worn valve face and seat, valve head level with head face instead of being proud-- then the spring assembled length will be longer and so exert less tension to the valve making them easier to open.

If the valve seat and valve head face are within spec it could be assumed that the test length is close to the assembled length.
I am not aware of a valve stem length dimension above the head upper face to go by as a guide for all being in spec.

There are two specs given and so called later engines have much less valve opening tensions than early units.
From my 6U Parts Book I see a spring change at 6U03945 from 5B6030 to 5F3112--outer spring, and 1B9704 to 5F3111--inner spring, the 7U may be as early too--sorry, I do not have a 7U P.B.
Cheers,
Eddie B.