[AG]

What shim thickness behind the pressure relief spring in a 60 psi pump is required to get 70 psi?

[steve25]

Measure your compressed lenght of spring now and divide that by your current oil pressure of 60 to 65 lb.

["QUICK-SILVER"]

Make a block off plate to bolt where the pump mounts to the block. Drill and tap a hole in the middle of it for a screw in mechanical guage.

Bucket of oil and drill...then you can set the spring tension exactly where you want it.

Clay

[Tom Vaught]

Originally Posted by steve25

Measure your compressed lenght of spring now and divide that by your current oil pressure of 60 to 65 lb.

Can you post up Steve how you would come up with the compressed length on the spring on his pump?

Tom V.

[steve25]

Oil up the spring port, pack clay into it , screw the cap plug on and then remove the clay and measure it.
Also set a washer in first that fits close and subtract your washer thickness from your clay measurements.

[Skip Fix]

I tried measuring oil pump springs on a valve spring tester. They are so light it was hard to tell any difference.

[steve25]

I've done that same thing Skip , that's why I took to lenght measurements.
I did a chart on the 80 lb pump years ago but can't track it down lately.

[Tom Vaught]

Originally Posted by steve25

Oil up the spring port, pack clay into it , screw the cap plug on and then remove the clay and measure it.
Also set a washer in first that fits close and subtract your washer thickness from your clay measurements.

More detail on packing this clay inside the pump please.

Tom V.

ps Skip I can put the cover on the spring and compress and screw the cover on the pump
with one hand. Yes a very light spring. And difficult to measure with accuracy on any spring tester unless a very light psi tester.

["QUICK-SILVER"]

Originally Posted by steve25

Oil up the spring port, pack clay into it , screw the cap plug on and then remove the clay and measure it.
Also set a washer in first that fits close and subtract your washer thickness from your clay measurements.

This not something you could do with a dial/digital caliper?
Correct for how the spring sits on the ball, bore length, then depth (spring rest) in cap nut. Just seems like it would be easy.

Clay

[72LuxuryLeMansLa.]

Why 70lbs. ? Why not 80lbs. or 60lbs. I'm just curious, not trying to solicit any particular response.

[Tom Vaught]

Originally Posted by "QUICK-SILVER"

This not something you could do with a dial/digital caliper?
Correct for how the spring sits on the ball, bore length, then depth (spring rest) in cap nut. Just seems like it would be easy.

Clay

I took some of those measurements:
a) Edge of regulation Ball to spring nut mounting surface 1.070"
b) Spring free Length 2.300" (My spring was 2.292")
c) Nut mounting surface to pump = .280"
d) Depth of oil spring pocket on the nut = .443"
f) Pump cover height = .625"

So you have all of those different dimensions, all capable of changing during production.

Luhn Performance actually built a 'Oil Pump Dyno' tester that seems to work well and can hit a oil pressure number really close. I believe that they did some actual shim thickness testing and know what a real shim does to the oil pressure.

Might want to call them

Tom V.

[Formula8]

Lets not over complicate this. I did a search on this a while ago and the consensus was .060. Some have used up to .100. That said if a .060 produces approximately a 10psi increase using the 60psi spring, a .100 shim is going to produce what? 76 psi or so?

[Squidward]

Originally Posted by Formula8

Lets not over complicate this. I did a search on this a while ago and the consensus was .060. Some have used up to .100. That said if a .060 produces approximately a 10psi increase using the 60psi spring, a .100 shim is going to produce what? 76 psi or so?

Yup. I did a Melling 60 psi pump, dropped a hardened 1/16 thick washer (.06-ish) in the spring hole, and called it good. I did this for both of my current engines. I can't remember what the hole diameter was, tho. But use whatever is large enough to fit without getting stuck.

[aceaceca]

Well, I once used a 1/4 nut with the peaks rounded off on a 350 Chevy. It blew the filter up and made a nice mess of things.

[CROCIE JR]

.060 is worth 15lbs on a small journal with .0023" on the mains and .0028" on the rods and VR1 30wt. I think I used a AN washer.

[CROCIE JR]

Thats with a .034" lube hole in the front and back.

[AG]

Thanks all for the recommendations, looks like a 0.060" shim.

[Tom Vaught]

Originally Posted by CROCIE JR

Thats with a .034" lube hole in the front and back.

Don't forget about the .034" lube holes in his engine.

Tom V.

[RA462]

I use a 5/16 lock washer that I flatten out. Usually gives me about 70 psi in a 60 pound pump. You might have to grind a slight amount off the OD of the washer to get it to fit inside the spring cap.

[AG]

Originally Posted by Tom Vaught

Don't forget about the .034" lube holes in his engine.

Tom V.

I always use one.