Oil pressure too high?
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Oil pressure too high?

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    Default Oil pressure too high?

    A buddy of mine is getting ready to fire the 427 bbc in his flat bottom and when he runs the pump with a drill he is getting 100 psi pressure at the gage. Is this going to cause a problem? He is using 20W 50 Valvoline Racing oil. The engine has been sitting for quite a while, is it possible the by pass in the pump is stuck, would that even cause this? It has the stock GM oil filter adapter .

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    gn7
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    Quote Originally Posted by VD Cruiser View Post
    A buddy of mine is getting ready to fire the 427 bbc in his flat bottom and when he runs the pump with a drill he is getting 100 psi pressure at the gage. Is this going to cause a problem? He is using 20W 50 Valvoline Racing oil. The engine has been sitting for quite a while, is it possible the by pass in the pump is stuck, would that even cause this? It has the stock GM oil filter adapter .
    Its possible that the pumps RELIEF is stuck. The filter BYPASS has nothing to do with oil pressure except if the filter is blocked or the filter cannot pass enough oil because it too thick or the filter is too small.

    I'd fire it, keep the Rs down till the oil heats up and see what the pressure does. Its VERY possible that the engine doesn't need a 20-50 oil and its simply too thick.



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    Quote Originally Posted by VD Cruiser View Post
    A buddy of mine is getting ready to fire the 427 bbc in his flat bottom and when he runs the pump with a drill he is getting 100 psi pressure at the gage. Is this going to cause a problem? He is using 20W 50 Valvoline Racing oil. The engine has been sitting for quite a while, is it possible the by pass in the pump is stuck, would that even cause this? It has the stock GM oil filter adapter .
    Is there oil coming out at the rockers?

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    He didn't run the pump long enough to get oil out of the rockers. Also I wasn't there to see what was going on. How much pressure will a filter take before it ruptures?
    Thanks GN7 for getting me straight on the terminology.

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    A good filter like a Baldwin, K&N, or Wix will hold about 300 before rupturing. The internals will collapse well before that, but thats only if the pressure into the filter is considerably higher than the leaving. 200 in and 175 out (in the block) will not harm the filters internal. But 100 in and 25 out will crush it. Its the DIFFERENCE between the in and out that crushes the internals. Usually caused by a lack of a filter bypass, along with the oil too thick/cold, clogged or too small of a filter.



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    I had a situation where the oil wasnt getting past the lifters and up the pushrods. It showed high pressure. Had to do a little dremel machine work to get the oil up the pushrods and circulating.
    Actually if first started with the oil not getting past the cam bearing at the back of the block, had to put a groove in the cam in order to get the oil past, then I had the situation with the lifters. It is the early model big block 1966
    Last edited by PropWorks West; 09-08-2012 at 07:19 PM.

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    That's thick oil when it's cold. I'd fire it. 100psi cold isn't uncommon with grease in the pan. I don't understand why people feel the need to run that thick of an oil....modern production engines mke more HP per cube than what most boats are making and they're good on a high HTHS 5w30, or thinner in many cases....with a whole hell of a lot less bearing surface. Remember...fluid pressure is simply a restriction against flow.
    Last edited by lbhsbz; 09-08-2012 at 07:54 PM.
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    Without the engine spinning and passages going open and close I would not go into panic mode until the engine was spinning with plugs out to get oil up top and see what it reads! My opinion!

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    Quote Originally Posted by PropWorks West View Post
    I had a situation where the oil wasnt getting past the lifters and up the pushrods. It showed high pressure. Had to do a little dremel machine work to get the oil up the pushrods and circulating.
    Actually if first started with the oil not getting past the cam bearing at the back of the block, had to put a groove in the cam in order to get the oil past, then I had the situation with the lifters. It is the early model big block 1966
    Ah-ha! Yes, this is something you Chevy guys should be aware of. The early big blocks did not come with the rear cam bearing housing in the block machined with a groove all around it, like all the later blocks do.

    There is a special, different part number for the early BBC cam bearing set, made just for these engines, that has an oil groove cut into it, to send oil up to the lifters/pushrods/rockers. It's common to early 396 blocks. It's in the Dura-Bond application book.

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    Thanks for the comments guys. The guy bought this deal about 11 years ago. He saw it run, but didn't take the boat out, he said the oil press was pretty high then. We changed the cam and looked at a few bearings, the engine looked good inside. Don't know any history on the engine, it may have the wrong cam bearing in it and yes it probably doesn't need oil that heavy. I'll suggest a lighter oil.

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    my 427 runs 80 psi cold idle and hits 100 at 5k warm so it may just be the way they are. warm idle goes down to 65 but still hits 100 even at 180* anyway nice engines for a well balanced flat <br><br><br><br><br>
    It may be OLD ,it may be Slow ... but at least it's MOBILE !!!

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