Old Rol-Air K25 information needed

[N_Jay]

I was going to come here to help identify my compressor pump, but have since found out (fairly sure) that it is a Rol-Air K25 (K24).
It might have been an OEM version for Matco based on the gauge on the tank.

It has a few differences from the current generation.

The crankcase has ribs only on the sides, not front and back.
The crankcase fill/vent is on the front corner not back corner.
The bearing carrier on the back has a round pattern not a square pattern.
The intake and outlet are pipe thread not a gasket/o-ring fitting.
The fins on the head spread out over the low pressure piston instead of being parallel.
The intercooler is larger.

Would anyone know that exact model number or maybe have a service manual?

Here is the current generation:
https://www.rolair.com/products/pumps/belt-drive-two-stage/pmp22k24ch

 

[N_Jay]

Rol-Air came back with an answer.
It is a previous generation K24/25 pump.
All the current generation parts fit.
They even threaded the intake and outlet so it can fit both older pipe thread connections as well as the newer flange connections.
That is thoughtful design!

A person on another forum told me he had a Rol-Air pump that was built in 1945 and was running fine till last year.
Replaced with another Rol-Air when it finally broke.

I hope mine is as solid.

 

[N_Jay]

So upon better inspection the pump is a Rol-Air (Chinook) K28 from 1986.

In my clean up of the pump, I found that there is an adjustable relieve valve on the bottom of the intercooler.
Unfortunately the setting screw is loose, so I am not confident that it is set correctly.
I have not found any information on what PSI the valve should be set for.
Any suggestions?
I found one internet reference that these are usually 75 PSI, but looking for better information.