[Formula jg]

I have a mechanical gauge feeding from the hole next to distributor along with the OEM gauge connected to sending unit at the filter housing. The pressure at distributor is approx. 10-15psi lower than the filter housing reading, is this within a reasonable range difference?

[steve25]

Yes.
The oil does not get to that hole until it has passed thru the filter and gone down the passenger side lifter galley and then over to the drivers side galley to then get to that hole last.

[Formula jg]

Thank you Steve.
I have a remote oil filter located behind the pass. side headlight, does that reduce overall pressure a little more?

[Scott65]

What is reasonable? I see 2 psi drop at those 2 locations. Before I'd get nervous I'd try something other than a factory gauge first.

[steve25]

Don’t forget that when the motor is up to temp and the oil is also that the bypass is closed so all that volume is first going thru the filter before getting to any of the galleys and making for whatever pressure drop the brand of filter your running produces,

[Nobuddy]

Originally Posted by steve25

The oil does not get to that hole until it has passed thru the filter and gone down the passenger side lifter galley and then over to the drivers side galley to then get to that hole last.

If I understand what you wrote, that is backwards, at least one the few Pontiac V8 blocks I have worked on. The plug on top next to the distributor gets oil before either the driver or passenger side galleries. Pressure loss there would be the filter housing, filter itself, and the one 90 degree corner in the block. There is a horizontal passage from the filter pad over to the driver side, then up to intersect the driver side lifter gallery, The plug on top seals that vertical passage.

[lust4speed]

Nobuddy is correct, there is only about 12" of passage (8" horizontal and 4" up) between the oil filter adapter oil pressure outlet and the block outlet by the distributor. The B-body 90° filter adapter has the oil pressure outlet after the filter cartridge while the angled A-body adapter has it on the feed side before going through the filter. Even with the A-body design, as long as the filter bypass is working correctly there should be less than 5 PSI loss through the filter.

Gauges are notoriously inaccurate and I would bet that the pressure difference you are seeing is probably a difference in gauge readings.

[Bill Hanlon]

Originally Posted by lust4speed

Gauges are notoriously inaccurate and I would bet that the pressure difference you are seeing is probably a difference in gauge readings.

I agree. Put a T on the filter housing and connect both gauges there. Plug up the hole near the distributor. Crank up the engine and note differences in pressure between the two gauges at various engine RPMs.

[mgarblik]

Originally Posted by Bill Hanlon

I agree. Put a T on the filter housing and connect both gauges there. Plug up the hole near the distributor. Crank up the engine and note differences in pressure between the two gauges at various engine RPMs.

I agree with above. Remove the variables, use a T. However, the pressure should be nearly the same at either location. You are basically monitoring the same passage, one at the bottom, at the oil filter adapter, and the other at the first place oil goes in the engine basically at the beginning of the main gallery. See diagram from 62 factory service manual. There is some filtered oil taken to oil the rear main bearing directly off this passage. That could drop the pressure slightly. Other than the stud oiling, the circuit was unchanged for the life of the Pontiac V-8.

[Formula jg]

That's a very good way to verify any difference in gauge readings, thank you Bill.

[Tom Vaught]

Originally Posted by steve25

Yes.
The oil does not get to that hole until it has passed thru the filter and gone down the passenger side lifter galley and then over to the drivers side galley to then get to that hole last.

I AM SORRY BUT THAT IS TOTALLY WRONG, STEVE.

1) Oil flows from the oil Pump to the filter as you said.

2) Oil flows from the filter thru a cross-passage on the rear face of the block to a vertical channel on the Drivers side of the block. That is where the plug is that is next to the distributor.

3) Oil also flows from the cross-passage toward the front of the block and feeds the driver's bank of Lifters and the related valve gear as well as feeding the main bearings Rear bearing first, then each bearing as the oil moves forward. (The passage that feeds each main bearing also feeds a cam bearing
AFTER it feeds the main bearing.)

The oil is now at the front driver's side of the block, it feeds the front main bearing and there is a drilling that feeds the passenger side lifter gallery.

That passenger gallery gets fed LAST, not first as you have posted.

Some people drill a hole in the plug next to the distributor shaft to remove air from the passenger side oil gallery and lubricate the distributor gear.

Sorry but your post was totally backwards.

Tom V.

That plug next to the distributor can read oil pressure accurately as the oil begins to feed the passages in the block.

[Formula jg]

Update. I added a T-fitting at the oil filter housing and connected the mechanical gauge next to the electric sending unit. The readings were identical for both, I was surprised on the accuracy of the electrical sending unit.

This confirms my setup has approx. 10psi drop between the OEM filter housing and the plug next to distributor. I’m guessing there is a little more psi drop because of the additional distance the oil has to travel to my remote filter located behind the pass. headlight.

[Tom Vaught]

Having done several remote oil filter installs on our Engine Dynos, I would say that your assumptions are pretty accurate with your set-up. We used remote set-ups because we tested at different oil pressures by using a by-pass circuit to control the oil flow actually feeding the engine. We did not mess with the oil pumps/springs which would be a major PIA if we were changing oil pressures.
Tom V.

[johnta1]

How long are your lines?
Rubber?

I usually try to keep it less than a foot to remote filter.
Lots of friction loss in rubber lines also.

[Formula jg]

Lines are industrial hydraulic type and they are long approx. 3ft from block adapter to filter housing. I wanted the filter out of sight and not on the inner fender or firewall so it’s up behind the pass. head light.

[Formulas]

What size / diameter are your lines internally?

[Formula jg]

3/8” ID.
I found the hose specs online based on the code numbers stamped on the hose.

[Nobuddy]

Suggest you use 5/8" ID hose. Maybe 3/4" considering the length.

[lust4speed]

Three feet of hose coming and going adds six feet of additional plumbing. The 3/8" size is small and wondering if the observed pressure loss was at idle? The loss would increase with RPM and could be scary up at higher revs. I've used -10AN on about the same length run to a dual remote filter setup with the filters flowing in parallel and still saw eight pounds loss at shift RPM.

3/8" = -6AN
1/2" = -8AN
5/8" = -10AN

[Formula jg]

Good suggestion, I’ll look at changing these lines out for larger ones.