T56MaxTorq
Well-Known Member
With that plug out or dislodged, the engine would see higher pressure from dirty oil, but would trash the bearings quickly. This would lower the pressure as the bearings wear out. explaining why the filter is clean.
Low oil pressure?
- Thread starter Cope
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You have other problems like too tight of clearance or not cleaning out the passages, A lot of guy bead blast parts and the glass gets stuck in the casting and wont come out till the temp comes up and then it goes through the pump, if its a cheap filter and the bypass opens at 8-10 psi then at high rpm's it opens and the glass exits the filter and trashes the bearings. I ran the same bearings for years and ran my 340 to 7600 and a few times to 7800 and the bearings looked like they did when I took them out of the box.
Without the plug the oil can Loop back through the oil filter through the oil pump passage in the block back through where the plug is missing back to the filter or the pump blick passage and at the same time be feeding oil into the passage to the passenger side galley.
not saying the oil is going back into the pump. I'm saying it follows that passage back toward it from the pressure of the unblocked passage.
not saying the oil is going back into the pump. I'm saying it follows that passage back toward it from the pressure of the unblocked passage.
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Good oil pressure gauges are cheap. What "I" would do........get a GOOD gauge.....a nice Autometer and make an oil pressure testing gauge. VERIFY that your oil pressure is really low. THEN you will know what to do for sure.
T56MaxTorq
Well-Known Member
Seems counterproductive to design and manufacture a filter that would do its job in filtration, but when differential pressure is too high, the bypass opens and just dumps the debris into the exit passage.
I think the purpose of the bypass in the filter is in case the filter becomes plugged up you will still get oil into the engine by bypassing the filter internally. I may be wrong on that but I doubt it. I may not always be right but I'm never wrong.
Inertia
Well-Known Member
The alternative, oil starvation, would be just as disasterous. Until the filter valve opens the debris is trapped in the filter material. There is no "backflow" to dislodge it. Take a filter apart.
There I fixed your post. lol
agreed on this subject Jabroni
Call me whatever you want to. Just don't call me late to supper.
T56MaxTorq
Well-Known Member
R3 said the debris comes out. I figured that debris would be entrapped but looking online at a bypass filter breakdown, the oil flows past the filter media, so It’s only possible that debris could be picked up and forced in the system.
It should be designed so that the bypass isn’t even a function of the spin on filter, but rather the housing, like every normal differential pressure relief type system.
Inertia
Well-Known Member
If you got that much debris in your oil, you engine is ALREADY well on it's way to catastrophic failure. imho
T56MaxTorq
Well-Known Member
Sand, chunks of cork, silicone bits, carbon chunks, dried out rubber, oil sludge, normal metal wear - all those things can clog a filter and are pretty normal.
**** even extreme cold will force oil to bypass the filter. We have a recurring problem below 0* where a turboprops scavenge filter always pops a differential pressure indicator on startup.
**** even extreme cold will force oil to bypass the filter. We have a recurring problem below 0* where a turboprops scavenge filter always pops a differential pressure indicator on startup.
Marcohotrod
Well-Known Member
If the rocker shafts are on upside down, with stock rockers, pressure would be a little lower. 16 holes would be completely unrestricted
nm9stheham
Well-Known Member
You may be right... all depends on the how well the restriction made by the cam's 'oil flow interruptor' manages flow.
I just looked at a stamped rocker shaft from a '68 273 and the hole on top and bottom are the same size. Same on the adjustable rocker shaft I have here. So that restriction would not change. (Somehow I had the idea that the top hole was smaller.....??? Gettin' old....)
nm9stheham
Well-Known Member
That wouldn't even matter because the rocker shaft only gets a squirt if oil when the cam lines up and that isn't very long even at a idle. I did have a BB that had Mancini rocker shaft shims in them and they don't fit and basically the oil shot out under the shaft and that made the oil pressure gauge bounce bad at a idle but it still had pressure
nm9stheham
Well-Known Member
It actually appears to be part of the restriction.... the flow area restriction at the rocker shaft to pedestal hole and it's bolt (approx .034 sq in) is about 30% smaller than the flow area in the cam holes (approx .049 sq in). It is the smallest flow area in that whole path from cam bearing to inside of the rocker shaft. So when the cam holes do align, then this shaft hole-to-bolt clearance comes into the equation.
(FWIW.... The PRW rockers set that I have has that shaft hole to bolt clearance area reduced to .012 sq in. I called them about it and they seemed to indicate that was for some flow control, though they were a tad vague on that point. It was more of a statement that there was enough oil coming through there.... CYA maybe....)
(FWIW.... The PRW rockers set that I have has that shaft hole to bolt clearance area reduced to .012 sq in. I called them about it and they seemed to indicate that was for some flow control, though they were a tad vague on that point. It was more of a statement that there was enough oil coming through there.... CYA maybe....)
Marcohotrod
Well-Known Member
the O. P. does not have 273 rockers or shafts, he has stamped rockers. Dave Hughes said that as the rpms are up from idle there is a steady flow of oil up to the rockers, and I believe him, think about it, as the cam spins faster the flow is virtually full time. when a 340 shaft is installed correct, the oil outlet holes face down, and are partially blocked. If the shafts are upside down, the 16 holes face up and are wide open, lowering oil pressure
yellow rose
Overnight Sensation
Dave says that a lot, but Dave is wrong. As RPM goes up the time window is less and less. That's why Chrysler has said from the get go never restrict oil to the top end. It's self restricting.
Duane
Well-Known Member
O.K. Duane that's what you get for reading a book, the book is wrong!
look at the oiling system schematic and tell me why there would be no oil pressure. Here is a picture of the bypass plug, I just makes the oil go through the filter if the plug was not there the oil would still go through the motor and still have pressure it just wont go through the filter.
look at the oiling system schematic and tell me why there would be no oil pressure. Here is a picture of the bypass plug, I just makes the oil go through the filter if the plug was not there the oil would still go through the motor and still have pressure it just wont go through the filter.
Duane
Well-Known Member
Well this is only my opinion but I believe without the plug the oil would loop and have no resistance so it builds no pressure. With the plug in there it forces the flow path to go through the filter and then into the motor where it encounters resistance. The pressure then would equalize on both sides of the plug which may be why the plug does not blow out. Just my opinion. The book may be wrong, I just wanted to share another reference.
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