Saginaw Steering Pump Upgrade

The stock pressure of the 1973 Nova Steering pump is ~900 p.s.i. and the 1988 IROC steering pump likes around 1200 p.s.i. Fortunately the 1973 steering pump can be modified to put out more p.s.i. This mod is well documented both by David Pozzi and is also found this GMTruckCentral.com tutorial which is quite good.

Note: The stock p.s.i. and mod p.s.i. is estimated. Pozzi says based on an article from Lee Power Steering removing the shim(s) will result on 1400 p.s.i where the tutorial at GM Truck Central says it'll net 1200 p.s.i.

Here's the overview:

 

I left the mounting bracket on the pump and clamped that in the vice. A 1" socket fits this fitting. 

 

You'll get three parts. From left to right they come out in this order. 1) Main fitting (The part the hose screws into), 2) Flow Piston (Contains the High pressure Bypass; note the one washer/shim under the nut.) , 3) Piston Spring (I had to use a pick to pull out the spring.)

 You need to disassemble the Flow Piston. Possi suggested using a soft vice surface and putting a drill bit in one of the side holes to offer addition resistance. I sat a bolt in there to essentially reduce the length of the bit so it wouldn't bend/break. At this point the 7/16 nut released fairly easily with no scarring on the piston.

  

1. Remove the Washer/Shim(s) from the Piston. Mine had one. From left to right: Piston Housing, Spring, Limiting Stud (Note: look closely the limiting stud is still in the spring I forgot to pull it out for this pic), the Washer/Shim, Check Ball/BB and the End Cap.
2. Drill the Main fitting to 5/32"
3. Stretch the spring to 2-1/4".

Reassemble and install in your pump. I replaced the power steering fluid using AC/Delco 10-5030 and I fully bled the PS system by turning the wheel back and forth ~20x with the wheels off the ground (a good workout). I fired the motor and turned the wheel lock to lock and pushed out the remaining air.

I took the car for a spin around the block and the steering is definitely better that last night after the steering box install. I still don't have much return to center but the steering is crisp and there is no wobble.

I did have a little steering pump squeal at first but that went away. This pump has always squealed on start up when it was cold, so just for fun the pump may get replaced next. But the good news is I can use my upgraded Main fitting and Piston in a replacement pump.