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 Post subject: Oil filter bypass
 Post Posted: Thu Jan 10, 2013 12:47 am 
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Joined: Mon Apr 30, 2012 10:01 pm
Posts: 140
What is the deal with blocking the bypass? Do you tap it and plug it? Do you need a special filter then? Does this raise the gauge pressure? Is this really a good Idea. Some say it causes all of the oil to filter. Is the bypass just there as a safeguard against the filter from bursting. Also is there a chance that a Wix or Napa Gold could burst if pressure goes beyond 60? I have heard of some of the old-timers making there own high pressure pumps by shimming the springs and the filter burst. I have a higher pump, but I start at 55 and go down to 40 with a Wix and 20w 50 (Champion hot rod oil). I am just past my second oil change after a newly machined engine.

This is on an Olds 455. Yes I am an oddball.


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 Post subject: Re: Oil filter bypass
 Post Posted: Thu Jan 10, 2013 7:43 am 
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The filter bypass was built into the stock SBC filter adapter to allow oil to bypass the filter if it ever became clogged, for whatever reason. That bypass could also open when the oil is cold allowing unfiltered oil to engine bearings. Not sure how the Olds one works but I do have a friend that does Olds engines and I'll ask him what he does with his.

On an SBC this is a simple matter of removing the relief valve and spring from the filter adapter that's mounted on the engine block then using a 1/4" pipe tap to thread it then inserting a pipe plug in the hole with locktite. I've done this on every SBC I've ever built that uses a stock filter adapter and never had a problem.

As for the filter blowing up, I've heard of this but never seen it. I've run high volume/pressure BBC oil pumps in SBCs since back in the 1970s (yeah, I know they rob HP but.....) and I've also seen oil pressure @ 100 psig before too and never blown up a filter.

FYI, some oil filters have a built in bypass valve also. The external oil filter I run on the race engine is a NAPA Gold for an Isuzu truck that has NO bypass or drain back valve.

If you use the search function here on the board you "might" find some additional info on filters WITHOUT bypass valves.


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 Post subject: Re: Oil filter bypass
 Post Posted: Thu Jan 10, 2013 9:24 am 
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Joined: Mon Apr 30, 2012 10:01 pm
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I guess the loctite seals it from leaking, since it will only dry in the absence of air. I hate to expose Teflon tape to a system if I don't have to. Small pieces will never dissolve.

What is the appearance of a filter without the bypass. How does it look different? Is it solid except for the threads? Without the rubber plugs going around the outside?


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 Post subject: Re: Oil filter bypass
 Post Posted: Thu Jan 10, 2013 10:27 am 
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There was a link on here at one time to a site that listed which filters had the bypass and which did not. The "Search" function on here is your friend. ;-)


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 Post subject: Re: Oil filter bypass
 Post Posted: Thu Jan 10, 2013 8:44 pm 
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Joined: Mon Apr 30, 2012 10:01 pm
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Ken, I thought you were the "Search" function!

OK, I will try it. I am not in a real big hurry. I Had to go back to work.


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 Post subject: Re: Oil filter bypass
 Post Posted: Thu Jan 10, 2013 10:00 pm 
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just primer wrote:
I Had to go back to work.


I had a job once! =; Never will forget it! ;-)


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