Are guys still blocking off the bypass oil filter housing like H-O used to say to do
 

I'm building a stroker 462ci for someone and I'm not sure if I should block off the oil filter housing bypass like HO had in there book back in the day. I always have done it, but over this pasted summer, with my own motor I had my Wix filters clasping one after the other. So, I'm just wondering if anyone else has had this happen to them with or without it blocked off?

Thanks

Used to, but stopped that, and not gonna block em. Sick a magnet oil plug in and feel better about it.

2 rules of thought on this, one, you don't ever want to have unfiltered oil pass thru the engine. Two, in most cases if it does bypass the filter, it won't make enough of a diff to matter and the bypass is a level of safety.

Most oil filters do have some type of bypass built in, so...

Obviously, if the filter collapses, that's not good, and it would be better to have a bypass in that case.

You have to be mindful of you filter choice(s) and warm up procedures, especially if you block it off. Your oil psi needs to be kept in mind too.

When an engine is cold, without a bypass, you could potentially starve the engine for oil for a period of time before it reaches where it needs to be, longer than if the bypass were to open.

Filters need to have a higher burst rate rating if you block it. Or should. So it's good to know what that rating is for a filter you choose.

If the filter media filters to a refined level, it can clog faster and that would decrease oil flow, hence increase back pressure/decrease oil psi. This is one reason I don't use K&N filters, they need to be changed more frequently or they restrict flow and increase risk of blow-offs/collapse. I think the HP line does have a bypass, can't recall at the moment though.

Oil filters don't universally have a bypass valve, it can be dependent if the application is known to have a built in bypass valve or not. If you pick one for an app that is known to have a OE built in bypass, and you block the OE bypass, then you run the risk of collapse/blow-off.

This can be the case when people switch to remote filter setups, eliminating the OE bypass.

Long story short, in general, leave the OE bypass in place. IF you do choose to block it, be mindful of the filters you use.

I generally don't block them, the risk comparison to me is a wash. I do though have it blocked on my 535, but that's only because the builder chose to do so. I might change it back, but haven't gotten to that thought yet.

What's the part number on the Wix that you are using, and what are your oil change intervals?


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HO racing at that time sold the Lee Maxi filter ,
This was a two stage filter and had a section in it to still filter the oil and feed the engine when the bypass opened.

If you want to block the bypass you need to run either a 2 quart filter that can handle the highest volume of oil that the pump can move, or a screen type supplement filter.

That's great, all filters should have that, but it would compromise the life of the element.

A larger body filter would overcome the limitations of flow, but with headers it would be a task to fit without going remote.

O-Berg or screen type is an option, no worry of collapse, but the small filter area makes it to where you would have to clean it fairly regularly.


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Are you sure that's how they worked? Trying to figure that one out. Do you mean if the bypass in the filter opened if would still be filtered?

https://www.youtube.com/watch?v=Z9DAp4DXsQY

https://www.hotrod.com/features/oil-...-982-1046-98-1

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I’ve collapsed quite a few Wix filters even with a factory bypass on different platforms. Cold weather really tests them. We use Wix a lot, but these days there are often better made filters, they seem like they are cheaper made all the time.

My preference is to pick a filter that has a higher built in bypass pressure with the external GM bypass blocked. The original external bypass pressure on a lot of GM stuff was in my opinion to low. The low bypasss was ok for flat tappets, but causes a more issues with roller cams. I have mine blocked with roller cams, unblocked with flat tappets. I see a lot more bearing scars when running a stock external 3 to 5 low pressure bypass. The internal filter bypasses generally have higher differential pressures for better filtration.

Which filters do you use now?

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I run Baldwin filers and never have blocked the bypass.Tom

The B39?


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Ok thanks, that clears up a lot of what I was thinking about on this. Ever since this past summer having had my motor spin a bearing, I've been trying to figure out what actually made this happen, so I didn't make the same mistake again on the rebuild. So, after seeing the collapsed filter I started thinking back to the day before. I was beating on the car quite a bit and was noticing that the oil pressure was going really high thinking "this is odd" and was also thinking that it can't be a bad thing, so I continued and never thought anything more about it. Then I realized that the provision on the oil filter housing for the oil gauge is before the oil gets filtered through the pleats. So, if the filter collapses the oil is going to have a harder time getting through which is going to show higher oil pressure at the gauge. So, I can only imagine how low it must have been on the other side in the middle as it was getting fed into the motor. Yikes! lol So now I drilled and tapped a new location on the top of the housing where it will read after the filter. Now the oil pressure over all is different. It seems lazier not in a bad way but in a way that I understand why its acting different. That probably sounds stupid but it's hard to explain. ha-ha

Thanks for your theory on this it really helped me decide what to do for this build. It's for someone else so I want to get this build right with no problems

It was wix 51258

Would you ever use a non-blocked off filter housing or do you always block them?

Yeah I don't think that one has a built in bypass. And suspect you have the filter housing bypass blocked too. Which would give you erratic oil psi if the filter collapsed.

You should just put the oil psi sender by the distributor, which is at the end of the oil passage, giving you a more accurate reading of what the engine is seeing. If anything gets out of whack in the engine, many times you would see it from an oil psi reading from the end.




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FWIW, the KRE oil filter housings appear to not have a bypass: https://www.kauffmanracing.com/Ponti...%20Housing.htm

I leave the factory bypass in place. Its better to have enough unfiltered oil than to have not enough filtered oil. The factory engineers do things for a reason. I remember an article that was written by a well known engine builder that calculated that you would need 4 filters in parallel to run your engine safely without a bypass.

I used to block all of my filter adapters, never had any problems whatsoever with blowing or collapsing filters. I always used lighter weight oils usually 10w-30.

At first I used the the Lee Maxi 2-stage filters per H-O Racing recommendation. Later when the Lee filters went out of production I switched to NAPA Gold / Wix all without issues.

On my 421 HO build which is essentially a restored factory performance engine I opted to leave the bypass functioning as it was intended.

All of my engines would be considered stock to moderate builds. I always tapped into the port next to the distributor for my oil pressure readings.

B39 and B9 as I remember.Tom

I am not afraid of the stock filter housings with the external bypass on mild flat tappets on mild builds, but that is about it. What I have noticed is the better filter like a Baldwin (it generally has more filter element in it than the Wix) with the stock GM external bypass will often end up providing less filtration, or a very least, make no difference at all. With the better filter, the bypass opens more and it takes longer for debre to be caught in the filters.

When possible, I prefer plugging external bypass’s and switching to the in filter bypass that has a higher bypass pressure between 9 and 15 psi. I have no issues with blocking bypasses on street and strip stuff as long as the oil pressure is read after the filter so it reads the actual filtered galley pressure. That is what I do on Pontiacs with headers. But when blocking the bypass with no bypass in the filter the pressure needs to be read after the filter.

So, am I understanding this right. When you use a roller cam and lifters you will not use a bypass in the housing and you will block it off? I'm asking because I'm using a roller cam in the build I'm doing now, and I'd like to know what's the best way to go.
Thanks

I used to block mine. After swollen ac and wix filters, no more.


Better to have a short shot of "dirty" oil than to have a short starve of oil.

I don’t a run an external bypasses on roller cams. I block it and either run an internal in filter bypass that has a higher pressure differential (9-15 if a filter is available), or no bypass and make sure the pressure is measured after the filter. I try to keep full filtered oil in the oil galleys the best I can on all the roller setups.

So far since the late 70s I have blocked them all. No problems with AC Delco nor Napa Gold. My 500 runs 75ish PSI at WOT.

I still use a lot of Wix. I am not anti Wix. But Wix’s over all trend seems to be to make them cheaper, not better. I have had may share of issues with them. I have collapsed a couple of them and blown seals out.

The main brands we use are Baldwin, Fleetguard, and Wix (including Napa’s by Wix). I prefer Fleetguard of the 3, then Baldwin. Wix gets used when the other 2 are not options.

Fram makes a very nice well designed race filter. They have a screened bypass. The latest Champion laboratories filters appear to be very well designed to. Hopefully they survive the bankrupcy.

I ran a Wix 1049 for years, no issues. They are the early 60s big car filters, larger than the one for a 69 GTO.
But the new 461 got a K&P 35 micron screen filter because of header issues. I then installed a Frantz by pass filter to get the small stuff. The K&P has a very high flow rate and you have the choice of a by pass or no by pass with their filters.
I plugged my adapter and got the K&P with by pass. I take my oil pressure and get oil for the Frantz from the 3/8" plugged spot by distributor.
It all works great.

Don't block the bypass.

Do you do this because you're trying to keep material out of the needles or is there more to it?

What psi will the bypass in the oil filter housing start to open. Does anyone know?

It helps to keep from collapsing a plunger on HR cams. On pressure fed lifters it keeps foreign material out of the needles.

On a flat tappet I don’t care as much. My Grandpa’s 61 Biscayne had a 235 that didn’t even have a provision on the block for an oil filter, the suction screen was all it had. Lol

Those old external bypass’s are usually 3 to 5 lbs to bypass them, and the oil still has to get to the filter. If the spring is 50 or 60 years old who knows what is it yet. Lots of oil goes thru that bypass even a cruising speeds with them. OEM’s got rid of that design for good reasons.

Oh ok, I see why you block it now. If it's by-passing at 5 psi, then blocking it and just getting a filter with a higher bypass built in makes a lot of sense. So maybe I'll do that then because I'm using a roller. Sorry it is taking time to sink in. lol

You can also buy an aftermarket filter housings that does not have that bypass provision and are designed for modern filters with an internal higher pressure bypass. I think it is a different thread filter than a standard Pontiac. I don’t remember if it is nightmare or KRE that makes it.

Maybe for an all out high RPM race engine but overkill for anything else. Filter media blown loose and pumped through the engine is more concerning with sudden volume of high pressure oil than the random chance of hard debris (metal). Blocked bypass had popularity but never proven to save engines that were on their way to catastrophic demise regardless.

The bypass does not open based on absolute oil pressure. It opens when there is a pressure differential between the inside and outside of the oil filter element. An example would be a clogged filter element.

I put the link to the KRE one in post 15 - I have one on my 66 and it takes a standard filter:

https://forums.maxperformanceinc.com...1&postcount=15

I run a remote filter set up using a Wix 51515. Online information shows that it has an internal bypass.

Can't put it any better than that Wade!

For those "on the fence" regarding the bypass, I recommended doubling the bypass spring in the filter housing.

I ran a stock filter housing, no mods and a Wix 1049 for over a decade with a solid roller and had zero issues.
Street motor, leave the by pass alone IMO.

the lee lf 24 had a coarse filter about half the size of the fine filter. There were two bypass valves. 1 valve opened to let oil flow to the coarse filter when the main (fine) filter had some flow resistance and a standard type of bypass with a normal function. Therefore, you almost always got filtered oil to the engine.

Oh crap. 50 ys blocked bypass using delco filters(3 left-they still available?) Straight 30w.oil. Over 60k miles with100' burn outs. Pedal to the floor!

Oh crap. 50 ys blocked bypass using delco filters(3 left-they still available?) Straight 30w.oil. Over 60k miles with100' burn outs. Pedal to the floor! Guess 6200 rpm if shift in time...

This is what I've been doing in oval track engines after the Lee filter went away in the 70s, in street engines I kept the original spring.

With an 80 lb pump and a doubled up bypass spring, I have pushed oil out of the filter O rung on a cold startup. After that experience I always let the engine idle until the oil thinned out a little bit, that was also running 40 Wt racing oil.

Pontiac isn't the only engine brand where this dispute takes place, chevy guys dispute blocking the bypass valve also.

I have seen the filter elements implode a few times on different brands of filters causing lower end bearing damage. I never felt it was worth the chance to completely block off the bypass over worrying about a bit of dirt reaching the bearings. On the off chance a dozen small bits would reach the bearings it will embed in the bearing material and no major damage will result. If the oil has that much abrasive bits in it that it will totally ruin the lower end, you already have a bigger problem than blocking the bypass valve.

Having run a ton of Pontiacs on dirt, you absolutely will not keep all the grit out of the engine no matter what you do, it gets in there somehow. The air filter would ideally keep out anything larger than 10 microns in theory, but upon disassembly of one of these engines you might be surprised how much ends up inside of a formerly clean engine over time.

I adopted the Frantz by pass oil filters after I quit dirt track racing, If I were to build another dirt engine, or even a good street engine, I would currently use a Frantz, (as Troy, Dragncar, has already said he does) to keep the really small abrasive out of the bearings rings etc. All the oil in the engine gets run through a by pass filter every 3-5 minutes, so every drop is filtered to a sub 5 micron level frequently. if your adding abrasive at a rate faster than that, nothing is going to save that engine anyway, been there, done that.

There are IC engines that have no oil filtering systems used in racing (Briggs and Stratton, and Honda clone engines) that run in go karts on dirt and asphalt that run a long time with no oil filters on them, just frequent oil changes keep them alive. In 1961-63 Pontiac offered a block off plate option on the 194 tempest engine to eliminate the oil filter completely, I've posted pictures of that OEM part previously, so Pontiac engineers obviously felt at one point that if you changed oil frequently enough, the filter could be eliminated, and the engine would still be covered under factory warranty. I've also heard the theory that this option was for those that wanted to install a by pass filter system after they took delivery of the car, by pass filters were pretty popular aftermarket add on in this time period.

The air cooled small engines run in a fairly hostile environment when used in lawn care, and construction, and survive pretty well with just changing oil frequently. and no filter system, something to keep in mind when considering how important a filter system is, or isn't. ROI is a consideration, as is the upfront cost of the engine being protected by a filter system. Mainrtenance downtime is also a factor.

Likely the filter systems modified with no bypass valve are doing little in the grand scheme of things to keep the engine alive. I believe that the people that have adopted no bypass valves feel that they have accomplished something that really doesn't amount to to a hill of beans, but probably is comforting to them, and it likely won't hurt their engine unless the filter media collapses/ruptures, and dumps all the abrasives caught, directly into the bearings all at once.

Keeping the oil analytically clean by use of a by pass oil filter will filter much more dirt out of the engine oil than blocking the bypass valve valve of a standard OEM style filter anyway, (40 microns full flow, 5 microns bypass). You also gain at least 1 quart of capacity as well as there is going to be marginal heat loss from the oil as it passes through the extra plumbing and canister of a by pass filter. it's just a better system to use to supplement the OEM style full flow system already engineered into the engine.

Mu current thought would be use the OEM bypass system unaltered from original, supplemented with a by pass oil filter. Never worry about an implosion of the full flow element, and filter your oil to a standard much higher than any OEM system is capable of.

:2cents:

https://www.youtube.com/watch?v=gSFNpW6kmxc


Do Oil Filters Bypass at COLD START?
The Motor Oil Geek
297K subscribers

I don't really care either way. I leave it up to the person I'm building the engine for. Some like it, some dont.

When Bischoff built dads engine 10 years ago he blocked the bypass. It's had wix filters from day one and never an issue with 20-50 oil. It's what Tony did so I left it that way.

On my bird it has a functioning bypass. It's a stock build so I left it that way.

I change oil frequently with good quality oil and monitor with oil analysis so I don't have to worry about it.

Where would one source such a spring?

I 'used to' bend the spring retainer inward, but over time realized that was not a proper approach. I've never found the fiber disc dislodged, but guess that could happen.



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Which Fleetguard part number do you run? I know other non-Pontiac racer-people that run those.


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I removed a used spring from an extra oil filter adapter, then wound the 2 springs together, reinstalled both into the adapter I intended to use.

LF767 for a Pontiac with the OEM filter housing with tight clearance headers.

LF581 when there is more room.

LF3538 when there is lots of room.

The aftermarket filters housing that use the in filter bypass all take a different thread, 3/4” instead of 13/16”. These are common OEM Fleetguard numbers for older GM’s.

The whole unfiltered oil concept is a little deceiving to me as soon as you hear that most peoples thoughts go to immediate engine death OMG should never happen not one drop, But if you step back from the Clift and analyze the life of a drop of oil, It goes in clean and gets filtered most if not all the time one pass or another because they are designed to keep oil clean so there should not be a chunk of death waiting at the door in case of a bypass and if there is your engine is probably disintegrating at that moment and nearly no filtration system known to man is going to help

I agree, oil going thru the bypass basically never kills parts in the rotating assembly. It may leave a scar in a bearing, or a leave a score some place, but that is about it. Most flat tappet cams the lifter bleed rates are loose enough they can eat some debre and sludge and still function.

I do the filtering upgrades on Pontiac’s when the engine has a roller set up to prevent unfiltered oil that a shard of metal or piece of debre getting in the galley feed. It is extra prevention to keep the lifter’s feed free and clear on roller set ups to prevent collapse lifters and extend needle bearing life. That stuff does not apply to as much to splash fed mechanical lifters or a stock engine.

A secondary reason is after destroying engine bearings, with Pontiac’s stock bypass we did not save any of the roller cam parts when that happened, they galleys are all full of metal filings and everything is a mess. $$$$ of roller parts into the scrap barrel. After we started doing filtering upgrades with either the bypass blocked or higher bypass pressures, the roller valve terrain parts usually can get reused after an engine failure.