Power steering in 66 Skylark w/425 Olds motor

[Guest Buick_66]

I converted to power steering. I got an Olds 425 pump (rebuilt) and a Skylark steering box (rebuilt). Everything works except at idle. Very jerky, like it's not getting enough fluid to the box. Checked the pulley size - looks correct (5 3/8 dia.). Wonder if the relief valve setting is different between Olds and Buick. Any thoughts?

BobF

[joe_padavano]

All GMs of that vintage use the same Saginaw pump, so that isn't the issue. I've had a similar problem on one of my cars and it turned out to be a loose pressure valve that's located in the fitting under the pressure hose connection on the back of the pump. Unscrew the pressure hose fitting (dumping PS fluid on the ground in the process...) and check the valve assembly that's screwed into the center of the fitting on the pump. Mine was loose and when I tightend it up the PS worked fine. If the valve is tight, it may be contaminated an need cleaning.