[gtojeff1967]

I want to block the bypass spring on the oil filter housing, What oil filter should I use?

[steve25]

Are you running headers?

[wheneaglesfly]

If you do the Oil filter housing modification blocking the bypass then use only a Wix Racing Oil filter.
Or K&N HP 2003.
A Fram Racing Oil Filter is Ok too.

There has been devolpments that the Bypass valve should be retained.
Pontiac V8 engines need lots of Oil Volume flow.
Even a stock Pontiac V8 oil pump flows more oil than Big Block Chevy Oil pump does.
The bypass valve insures full.oil volume is delivered 2,000 Rpms & up.

I blocked the filter bypass valve in past too.
But I won't anymore..
K&N HP 2003 is all ever used and still do.

[TedRamAirII]

I think all oil filters have a built in bypass. When that bypass was built into the Pontiac housings, the oil filters were "full flow". I think I would block it off, you dont want the old one in the housing "leaking". Am I wrong? ; )

[428goat]

I have a oil filter housing with the bypass blocked if you are interested

[wheneaglesfly]

The bypass valve built into the oil filters is actually an anti drain back valve.

All oil filters used on 1959-60 -81 Pontiacs are Full Flow style.

Its a confusing topic. I spent 2 weeks and reading on another Hotrod & Race Forum I am on.
All makes & engines welcome.

Some of the best info was put out by a guy not liked here much.
B.F. Rock & Roll Engineering .
If You Google you can read yourself & decide.

[wheneaglesfly]

The modern ultra high efficiency dirt capturing oil filters do just that.
Filter down to 5 microns or less.
But also flow just 4-5 gallons per minute only.
Pontiac V8 oil pumps flow 11-13 gallons per minute.
Modded Pontiac pumps flow near double volume.
19-21 gallons per minute .

Best available spin on oil filters to fit the Pontiac Oil filter adapters flow at best 9-11 gallons per minute.

The Oil filter is always the restriction believe it or not.

Bypass valve Needed. Opens intentionally off idle speeds.
FULL FLOW OIL SYSTEM.
WHAT PONTIAC ACTUALLY MEANT.....BUT NEVER SAID DIRECT.

[wheneaglesfly]

If you examine the 1959-81 Pontiac V8 oil filter adapter its actually a very ingenious design .
Very High flow layout with net zero flow restriction.
That is once the phelonic fiber washer bypass valve opens intentionally off idle speeds crank rpms.

Chevy SBC, BBC, LSX does the same.
All do still.

[wheneaglesfly]

I did not want to believe also.
The guy heading the other forum I am on daily is a Retired Mechanical Engineer.
And he is good.

[TedRamAirII]

Originally Posted by wheneaglesfly

The bypass valve built into the oil filters is actually an anti drain back valve.

All oil filters used on 1959-60 -81 Pontiacs are Full Flow style.

Its a confusing topic. I spent 2 weeks and reading on another Hotrod & Race Forum I am on.
All makes & engines welcome.

Some of the best info was put out by a guy not liked here much.
B.F. Rock & Roll Engineering .
If You Google you can read yourself & decide.

A lot of modern filters have a Drain Back AND a By-pass valve. Of course the Pontiac filter cant "drain back" unless the filter is upside down. The drain back valve is usually a silicone flap just under the inlet holes to the filter, the by-pass is down at the very bottom and will open when there is a restriction in the filtering media or the oil is cold and too thick to flow "through" the filter. So that means you will have 2 bypass valves. One in the filter, and one in the housing.

[wheneaglesfly]

I am buzzing my 1965 Olds 425 V8 to 6,000 rpm.
Stock 40 psi pump.
Oldsmobile uses a similar cast aluminium oil filter adapter as Pontiac V8..
Left the bypass valve alone.
Zero issues.

[wheneaglesfly]

Originally Posted by TedRamAirII

A lot of modern filters have a Drain Back AND a By-pass valve. Of course the Pontiac filter cant "drain back" unless the filter is upside down. The drain back valve is usually a silicone flap just under the inlet holes to the filter, the by-pass is down at the very bottom and will open when there is a restriction in the filtering media or the oil is cold and too thick to flow "through" the filter.

Yes. Its not needed on Pontiac oil filters that silicone flapper deal.

[lust4speed]

While the anti-drain-back valve is a necessity on engines with the filter mounted sideways, there is still a benefit to using a filter with the valve on our Pontiac's. Most of the Pontiac oiling system is above the filter, and while the filter remains full either way, filters without the flap will allow oil galleries to drain out through the filter and back into the pan. The valve will keep some of these passages full, and the time for restoring pressure at startup will be quicker.

[TedRamAirII]

Originally Posted by lust4speed

While the anti-drain-back valve is a necessity on engines with the filter mounted sideways, there is still a benefit to using a filter with the valve on our Pontiac's. Most of the Pontiac oiling system is above the filter, and while the filter remains full either way, filters without the flap will allow oil galleries to drain out through the filter and back into the pan. The valve will keep some of these passages full, and the time for restoring pressure at startup will be quicker.

I did'nt think of all that, but I would agree.

[Formulas]

I have actually destroyed the at the time recommended Lee oil filter.. I had a very loose bottom end with BME aluminum rods at .0033 clearance and extra clearance at the mains as well with the blocked bypass the downstream volume exceeded the filters volume and ruined the filter element it was rattling around when I changed the oil so there's that....... I think people get to wrapped up in the phrase 100%filtered in real life contamination is introduced slowly into the oil and at the flow and circulation rate if only 30% of the oil gets filtered the dirt will be captured before long and if your engine is disentigrating a full flow system will only buy you a short amount of extra time. ...So I leave the bypass alone as I experienced a possibility of more damage to my engine vrs. leaving it alone

[wheneaglesfly]

There have been reports of oil filters blowing off of the Pontiac oil filter adapters after blocking them off.
Its never happened to me.


To have 100% Filtration & True flow and no accidents of having the oil filter blow off on the street or track you need a Road race style or high end drag racing remote Dual oil filter layout.
If you go that far a Plumbed in oil cooler would be a nice addition .
All AN Race fittings. #10 or larger. Stainless Teflon.lined race hoses.Earls or Aeroquip.
Fragolia.
The direction I like to use myself.

[TedRamAirII]

Originally Posted by wheneaglesfly

There have been reports of oil filters blowing off of the Pontiac oil filter adapters after blocking them off.
Its never happened to me.


To have 100% Filtration & True flow and no accidents of having the oil filter blow off on the street or track you need a Road race style or high end drag racing remote Dual oil filter layout.
If you go that far a Plumbed in oil cooler would be a nice addition .
All AN Race fittings. #10 or larger. Stainless Teflon.lined race hoses.Earls or Aeroquip.
Fragolia.
The direction I like to use myself.

I wonder if the Pontiac NEEDS both? Maybe one bypass cant keep up and the volume is too great for the built in valve inside the filter?

[Sirrotica]

Quit worrying about the factory full flow filter because it does a halfast job of cleaning the oil anyway. In my engines I leave the bypass valve intact and run a superior filtering system that will keep the oil clean no matter what the full flow filter is doing, along with the bypass valve. I could actually remove the full flow filter, and just use the by pass filtration system with excellent results. If your wondering, it's already been done both by manufacturers and by people that knew the full flow filter is just a redundancy of a good by pass filtration system, 2 filters aren't needed if the first one is doing all the filtering anyway.

If you want the oil clean (1-2 microns) you need an auxiliary by pass filter system, besides the full flow. The by pass filter system does quality and not quantity as it doesn't attempt to filter all the oil before it is run through the engine. It filters the oil to a very fine degree at the rate of about 1 quart per minute and returns the fully filtered oil back to the pan.

The full flow system is flawed at best, and with a good by pass filter system it isn't even needed. Screw on a very non restrictive filter so that the oil goes where it's needed to keep the engine supplied. Expecting the whole volume of oil going through an engine at high RPMs is unrealistic, even at slow engine speeds all the oil is not going to be well filtered.

It gets filtered to a degree of 40-60 microns if the full flow filter is non restricted, and all the sub 40 micron abrasives will continue to circulate unfettered to wear internal components. As engine speed goes up the by pass valve opens and oil that can't go through the filter gets sent with everything carried in the oil right to the wear items in the engine. We already know that anything smaller than 40 microns is going to get to the wear parts because even at maximum efficiency the full flow filter can't remove anything less than 40 microns.

The bulk of engine wear is done by 5-10 micron abrasives that a full flow filter has no way of removing, so if they get sent through the bypass valve, or filtered through the full flow filter, they are still going to cause engine wear. The longer the oil is in a running engine the more sub 40 micron particulate it picks up and re-circulates causing wear.

The full flow filter design is an inexpensive flawed design, engineered by Detroit to do some filtering, but not filter all the oil and because it is stuck on the pressure side of the pump it can never efficiently filter the large quantity of oil pushed through it, or around it through the bypass valve.

There are much better by pass filtration systems made that actually keep the oil filtered to a like new condition and let owners stop throwing their oil out because the full flow filter is inefficient at best, and it is carrying contaminants smaller than the full flow filter is capable of removing no matter whose name is on it or how well they tell you it will filter. Anyone ever hear of any full flow filter that will keep crankcase oil so clean so it can be run for say 25,000 or more miles miles, not change it for over 4 years? I've done it myself in my diesel dually. My 05 GTO currently has 13,000 miles on the oil and 119,000 on the engine since new.

By pass filtration has it's place on all I/C engines, high performance or daily driver, gas or diesel. Clean oil is never going to hurt any engine, dirty oil will definitely hurt any engine. Even oil companies will tell you, oil doesn't wear out, it gets dirty and contaminated by inefficient filter systems.

[wheneaglesfly]

Originally Posted by TedRamAirII

I wonder if the Pontiac NEEDS both? Maybe one bypass cant keep up and the volume is too great for the built in valve inside the filter?

Without Engineering Testing its hard to tell say exact.

Its a complex topic indeed.

The bypass valve system used in the Pontiac V8 Factory oil filter adapter is larger than most other V8's of the past.
I would say the Pontiac Engineering knew what they were doing to begin with .

[Sirrotica]

If you attack the problem from a different angle, and filter the oil in a circuit other than on the pressure side of the pump, inline between the internally lubed engine parts, the solution is obvious.

Any oil system that moves a large volume of oil (I.E. hydraulic systems) don't filter it on the pressure side of the pump. A restricted filter will cause a problem with the system causing the pump to bypass oil and overheat it as well as starve the system. Most all hydraulic systems filter on the return side with no restrictions coming back to tank and at a reduced pressure with a large capacity filter.

There are plenty of race engines running an Oberg style filter that is nothing more than a fine screen to monitor engine health from particulate caught in the screen. They service the screen after each outing and also change the oil since in essence, they have no filter to clean the oil, nor cause a restriction and no real need for a bypass valve.

Maybe your overthinking this?
If you want clean oil, filter it before it hits the pump, and not after it's under pressure, and needing to get to critical engine parts before oil starvation/restriction causes engine damage.............

This quote from Machinery Lubrication, an online magazine dedicated to lubrication and filtering lubricants of all types of engines and machines. The publication is from industry experts as well as engineers in lubrication challenges in all types of equipment.

While having a cleaner lubricant can’t ward off an impending attack from old, worn rings and liners introducing combustion byproducts to the lubricant via blow-by, it can help prolong the onset rate of oxidation. Without exception, the cleaner, cooler and drier a lubricant is, the longer it will last in terms of oxidation.

Remember, fine filtration is always better than no filtration or poor filtration, since the additives will be depleted with or without filters. Plus, your machine and oil life will improve vastly with fine filtration.