Pressurestat on block (440)

[Red_Rocket_1965]

Hey guys-

I’m trying to go through and fix leaks and I thought I would double check the oil pressure gauge fittings at the back of the block. One port has a line to my mechanical oil pressure gauge and the other has a Y with a KYSOR pressurestat and the other is a sensor wired to the dash oil dummy light. I suspect that the pressurestat is wired between my electrical Holley blue fuel pump and the toggle switch and is the reason why it doesn’t kick on immediately when I flip the pump switch - fuel pump turns on after cranking a few times and oil pressure starts to build up. I’m guessing the pressurestat waits to see enough oil pressure before completing the circuit to the fuel pump. And perhaps it’s also a fail safe if oil pressure drops too low and it will stop fuel flow?

Is this a common setup? I cannot find specs on the pressurestat so I’m just gathering some opinions from b-body buddies since I did not build the motor…thx!

 

[bobsgtx]

The pressure rating should be part of the part number. In my former life we had those on diesel trucks and equipment before electronic diesels. They were wired so the pump solenoid would be energized when the starter was engaged and when you had oil pressure.

 

[bobsgtx]

Pressure should be lat two numbers of the part number. -10 10 psi, -06 6 psi etc.

 

[Red_Rocket_1965]

Part number is 24900-03…so 3 psi? You would think it should be rated higher. When I get it back together I can crank it and watch the gauge and see when the fuel pump kicks on

 

[bobsgtx]

Yes. 3 psi. I looked up a Holley switch and it says 5 psi. Wiring should be C- fuel pump, NC- starter relay/solenoid, NO- key run position. I have seen other ones that look like a plastic oil pressure switch for a light but have 3 spade terminals. If my memory is right (CRS) we never had much problem with them.