I need an opinion about plugging the oil filter bypass for my SBC. I've heard plugging the bypass will cause some oil filters to be damaged when the cold oil is forced through it and some have said that oil can be delayed getting to some important areas of the engine. I have had the bypass in my 350 plugged since i built it without any problems. I just thought I'd throw this out for some discussion and an opinion or two.
Thanks
Jim

All the sbc performance engines we build we plug the bypass and use the Wix 51061 or the NAPA 1061 gold has always worked for us. The 1061R flows more oil but has double the micron rating as the 1061 gold.

Fram filters have not worked very well when plugging the bypass due to not enough filter paper for the oil to pass through.

Jim,
If you are willing to use a top quality racing type filter, and ALWAYS warm the engine up before leaning on it, then go for it. We do it on some of the circle track engines we build but we also make sure the driver is going to do it our way, otherwise the bypass stays stock.
HOWEVER I have seen two engines destroyed in the last 4 years due to filters coming apart internally and blocking oil passages ... both times with blocked bypasses. Both were stock type filters. On a street driven car, I just dont see the need to do it. Most of us change the oil and filter more often than needed anyway on our hot rods, so chances of a filter getting clogged is pretty slim. There are a bazzilion Chevy engines running around with the stock bypass valves in them ... they dont seem to cause any problems.
Just my opinion,

Thanks Bill and Carl for your opinions. I too believe the stock setup works fine but when (at what pressure) does the bypass open? Just when the filter gets plugged? I was lead to believe that the bypass allowed 20% to 30% of the oil to be bypassed most of the time and this is why I went with the plugged bypass. I'm planning on putting the bypass back in as a just in case measure soon. This topic came up recently when I found a customers car oil filter leaking. After replacing it I found the filter was all messed up inside (Fram) I replaced it with a Amsoil filter and put the bypass back to stock. When we dicussed the problem the customer told me he was also running a high volume oil pump. I guess it's never too late to change what you believe is a good thing!
Jim

I was told by my engine man not to use fram filters for just that reason. Has anyone had this problem?

I did it on the race BBs using the two quart truck filters but never on a street car. There are two many things that can go wrong with the blocked by-pass on a street driven car that you don't watch every little thing.

I plugged my bypass last year and haven't had any trouble on the street. I use either the Napa gold or Wix filter that CNC BLOCKS N/E suggested.

I also run a std vol pump and 10w30 oil and always warm it all up before reving the engine. I drive my car about 4k miles each season.

If you ever toast a cam or rocker arm you'll be glad you plugged your oil filter bypass. It could save your bottom end.

Hi Jim!

My brother just took his 468 BBC apart last week in order to put a stroker kit in it. Last season he changed the oil filter (not sure which brand) and noticed the center of it had imploded. He was running with a blocked bypass.

On teardwon it was noted that the main bearings looked pretty bad, and this on about a 5K mile motor. Hard to say for sure if it was the fault of the blocked bypass - but best guess is that it was.

Sounds like a double edged sword to me. Pick your poison!

Already put it back to stock. Too scary the other way. At least I feel better about it.
Jim

What is scary to me is the thought of bits of toasted cam or valvetrain getting sucked up in the pan and pushed through all my bearings . . .

A friend of mine last summer lost the fulcrum bearings out of a couple roller rockers. We found every last piece of bearing either in the pan or in the oil filter :eek: Now imagine what a piece of fulcrum bearing would have done to his 427 BBC bottom end had one gone through the filter bypass and into a journal :eek:

If you like the bypass, at least get one of those screens that goes between the filter and adapter to catch any bits . . .

Good Idea Eric. One of those John Andretti screens. I was hoping the pickup screen would catch stuff like that. It's my understanding that the bypass stays closed until the filter is too restricted (how much pressure?)or the oil is too thick. Once again how much pressure does it take to unseat the bypass??
Jim

Do the issues with using a FRAM filter with a blocked bypass include the racing filters, such as the HP4?

How does the HP4 filter compare with the NAPA/WIX filters mentioned above?

I think using the screen (as Eric68 mentioned) with a working bypass might be a good answer for the street, although I have my bypass blocked.

Ray

That's just it GMJim -- noone seems to know for sure how much d/p across the filter it takes to unseat the bypass. When I had my filter adapter out the little plunger didn't even seal when closed, the spring had umpteen-billion miles on it so I got the impression it was always bypassing a little bit :eek:

If you have an engine problem and start puking metal bits you can rest assured that the filter will clog and the bypass will open . . . maybe I'm just a bit paranoid.

This is an interesting topic. Please allow me to think out loud for a minute.

If your bypass is left as stock, and you lose a rocker arm needle bearing or similar, as I understand things, unless the filter is plugged to begin with, the debris will go to the filter anyway.

Without really knowing any better, it seems to me that if you change oil regularly, and use a quality filter, it would make sense to leave the bypass in place.

With a blocked bypass, if the filter DOES get clogged, wouldn't the oil pressure then blow the filter up?

I guess I'm having a hard time seeing the advantage to blocking it on a well maintained engine, although it's a common practice among knowledgeable people. :confused:

We have been building circle track and street performance engines for 28 years now and always plugged the bypass and run the Wix 51061 or the 1061 NAPA gold filter with great success.

We have had engines come in from other shops over the years with out the bypass plugged and in most cases the cranks had to be turn as a result of debis getting into the bearings. Rick King from Kings Crankshaft Co. has been to my shop several times and has seen the condition of the cranks and the bearings when we take them out when they come in to be refreshened, 95% of the time we could put the same bearings right back in thats how good they look.

The Wix and the NAPA 1061 has far more filter paper in it compared to Fram filters thats why Fram filter don't work with the bypass plugged so that may give you some idear how much oil goes through bypass instead of the filter.

The more I think about this the more confused I get graemlins/clonk.gif You have valid points on both sides.

For example lets say the filter is not part of the equation, say it has 10x the filtering capacity of a stock filter( infact lets just say the filtering media is the size of my hood) :D lots of flow no back pressure

Now half the guys I ask will say a plugged bypass would be ideal in this situation because the extra large filter would not cause a problem/back pressure/restriction even with engine oil cold at high rpm(100% will flow through okay)

The other half of the guys say with that large flowing filter you can leave the spring loaded bypass in because it will NEVER open, bypass opens if there is a pressure differential between inlet and outlet of filter.

Sorry so long, Ray

Yes & Yes. It all depends upon the maintenance schedule of the lube system.

If stock oil system, leaving the bypass valve together and in the system, a stock engine will work fine.

If a special purpose engine, one is going to have an aggressive maintenance plan than stock.

Having no bypass valve does pump the oil through the filter first. A good thing.

I removed the bypass valve on Rosie and she works fine. I left the truck and others alone, they work fine. If it ain't broke, don't fix it!

I also noticed that my oil stayed cleaner looking with the bypass plugged. I used to change my oil at the 1000 mile mark, now I let it go a little longer.

It doesn't take much pressure to open the bypass. I have one on the shelf, I'll see if I can measure how much pressure it takes to open it.

As for me, on my high preformance engines I've always blocked the bypass, run a WIX filter and 10-30W synthetic oil.

No problems.

Bob.

I will be using the system1 reuseable filter(aluminum housing with stainless screen) I noticed that it has its own bypass(spring loaded ball) on the bottom.

So if I plugged the bypass in the oil adapter it could still bypass in the filter. I contacted sytem1 for their advice and they said many of their customers plug the GM bypass but that I shouldnt plug their bypass. They claim their filter will flow 30 gpm and the bypass will only open if the filter is 98% plugged.

So I guess they have/use a stiffer spring graemlins/thumbsup.gif

Ray

OK, off the shelf and onto the scale. Using a postal scale the GM bypass starts to open at 1-1/3 lb of pressure. With a 0.450" orifice I calc out to 8.3 psi to start the opening of the bypass.

Once the bypasss starts to open it will take less pressure to keep it open. This is because more of the valve portion is exposed (greater area) to the pressure.

Bob.

All good points. Al I look at it the other way, (not disagreeing with you at all) If you maintain your engine your filter won't get clogged and you can plug the bypass??? :confused:

I would like to add another twist to this. When I talked about this with my part time boss at the engine shop he said, what about Ford, Chrysler Honda, Mazda etc... (Being a Chevy guy, I'm not familiar with these) They don't have a bypass!!! All the oil goes through the filter. He also said he has found bits of the off the shelf Fram filters in pick up screens! :rolleyes:
Jim

On your Fords etc. the bypass is in the filter.

Since this question has come up I've been looking at a web site that did an oil filter study.
http://minimopar.knizefamily.net/oilfilterstudy.html It would seem that all oil filters have a bypass?
Jim

The by-pass opens at 10 psi.

You guys can do what you want, however i blocked off my bypass.

The K&N oil filter i have on the motor now has a burst pressure rating of 550psi.

The Wix Racing filter i have ready to go for the next oil change has a burst rating of 500psi.

I've changed my oil twice already and thoughly enjoy the fact that the oil i pour out of the engine is clean and the oil i pour out of the filter is dirty.

However i would NEVER wait 3000 miles to change my oil.

Make your own decision, its your motor.

Be carefull of the 1061R filter it is double (which will let bigger pieces through) the micron rating of a regular 1061 Napa gold, one other thing, Look how many holes are in the top of the 1061R for oil to pass through there are only 6 and on the 1061 Gold there are 8.

Ww have seen better results with the 1061 gold

cool, i'll pick up a napa gold.

I was thinking of using a Amsoil filter with a plugged bypass. I'm assuming the Amsoil has a built in bypass but I'm gonna check first. Anybody have any info on this filter?
Thanks
Jim

I think only the Furds and Moparts have the built in bypass.

I don't think any of the Chevy filters have an internal bypass.

The Amsoil filter has a bypass like the Ford filters, We didn't see good results with those filters in our performance engines.

If you going to block the by-pass on a street car keep an eye on the oil pressure guage and change the filter as soon as you see a drop in pressure.

Thanks oger
I've been researching this lately because it's been a topic of disagreement around our car circle. IMO What it boils down to is do you need a bypass on a street motor and I think the answer is yes. Not just because of leaving oil in the engine too long (most of us change our oil long before the average person), but because of thick oil on cold starts and those days when you're running a little late and you pull out of the driveway without warming the oil up long enough for it to pass through the filter fast enough. The idea of one eye on the oil pressure gauge and the other on the road all the time isn't a comfortable way to drive your baby. If you wanna race and do away with the bypass so be it. I think I'll use the stainless screen and keep my bypass working. This has been an interesting learning experience. I've never paid much attention to filters, bypasses and the pros and cons of either. The stuff iv'e read sure changed my mind about some filters I thought were the best.
Jim

I have had problems on the race car with cold weather and the 40wt race oil we used. I ended up changing the filter to get any oil pressure with the thickness of the oil and the partial plugging of the oil filter. Before you question the use of 40wt this was in a dragster with no radiator. When you start running laps the oil temp got real high and 40wt was the lightest we could use.

All good points here. I run mine blocked and have done so for years. I always use a quality filter and do not rev it much till the oil pressure comes down to operating pressure and temperature.

For those of you that do not want to run a blocked by-pass for your daily driver or any other reason, I would like to add this to the discussion. When you are breaking in a fresh cam, you can end up with a plugged oil filter from all the moly paste used on the cam/lifters. That is where the moly lube will go as it comes off the cam. Now that the oil filter is clogged with moly paste, the oil will bypass the filter while you are breaking in your new engine (or cam). :eek:

This critical break-in period is happening without any oil filtration. Not a good thing! If you can find an extra oil filter mount laying around, I suggest you could plug it up, install it for the first few hundred miles with high quality filters and then switch it back to unplugged after the break-in is over and the oil has been changed out. The filter mount is easily accessed when you do the second oil change and is held on with 2 cap screws.

Keep your by-pass and still protect the engine during start-up. Sort of a middle of the road answer ;)

-Mark.