Power steering issues

[bc69]

Have issues with lost power assist after car warms up. Power steering will work fine most of the time till engine compartment is warm. I'll pull in a lot and at low or revved rm cannot gain assist back. Belt is tight and fluid ok. The relief seems to bypass a little quicker than most to me. Would check pressure but not sure what is is suppose to be. Any suggestions?

[L78 steve]

You need to test pump pressure when cold and look at what happens when the fluid warms up. Pressure drop can be the pump or box. GM dealers have a Kent Moore tool to test pumps. But one can be made with a valve to add restriction while noting pressure and flow.
I can snap a picture of my set-up if you need it.

[bc69]

If you would it be great Steve. I'm hoping that it's a weak relief valve. Around what pressures should it run?

[L78 steve]

Pressures in 69 ran in the 900PSI range. But up to 1200 is better. Flow is also a bit low in 69 and when wider tires are added flow should be increased also. With a higher pressure (1200) flow will increase also to a point. These higher pressures will be a problem with a rad cam (stalling).
Picture of my pressure/flow set-up coming.

[bc69]

this is a original 67, L48 with standard tires.

[L78 steve]

First Gen Camaros will all be the same pressures and flow. I believe GM upped the pressure in 70.
Your first order of business is to find out where you issue lies then you can modify if you like.
Have you tried a different pump? That will be your simplest. Or any GM dealer will have the Pressure/Flow tester tool (required). For 1 hour of labor its probably worth it.