Which oil filter principle is better?

DRG-ler

DRG-ler

Senior Member
Hey guys, I'm thinking again.

I am considering retrofitting an oil filter to my Model A. However, I'm still pondering on what principle. There are off-line filters and full-flow filters. With the off-line filter system, the oil can continue to get to all bearings if the filter is "clogged". With a full-flow filter system, you can be unlucky because the pressure of the oil pump is no longer sufficient to push the oil through the filter. Especially since the oil pressure is already very low anyway. You have no real control over the oil pressure. What are your experiences?



Greetings from Berlin



Andy
 
Andy, there have been a few recent threads on this. I think the consensus was that the oil pump is actually capable of producing very high pressure if the flow of oil is restricted. Plenty of pressure to open the bypass valve on a spin on filter. I just added the valve cover mounted spin on kit and have no concerns about oil starvation.
 
i use the full flow filter system.

there is no pressure in the system because there is no restriction on the outlet tube in the oil gallery. if that tube is plugged the pump will build pressure.
the stock pump will create enough pressures to overcome the resistance in the oil filter.
the place that will restrict the oil flow more than the filter element is the anti-drain back flap inside the filter.
i have an oil pressure gauge on my engine and with the filter on the gauge never goes over 5lbs, this means there is no obstruction to the oil flow.
try to find a filter with the weakest anti drain back flap.
i have not heard of an issue with filter adapters.
 
I measured the pump pressure before installing the full flow oil filter. The normal oil pump reaches >80 PSI. When the engine is warm, the pressure difference in front of and behind the filter medium is <3 PSI.

Yes, a lot of knowledge can be found in the many previous posts on this permanent topic.
 
FWIW, I run the full flow filters on the side cover on all of my cars. There has never been a problem - about 90 -100 thousand miles between them.
 
Terry Burtz has said that too high of an oil pressure will stress the gears on the vertical shaft and the cam. He recommends no more than 35 psi.
 
This is only true for engines with pressure circulation lubrication through the hollow crankshaft and connecting rods bores and camshaft bearings.


But the A engine has no pressure circulation lubrication, the oil pump only delivers into the (open) cylinder head. The oil only drops down. (Hence the very low gauge reading.)


A distinction must also be made between the oil pressure that the pump can deliver (against a closed line) and the considerably lower delivery pressure in the rotating system.
 
Many Model A motors have been converted to full pressure systems, you have to first confirm what you have.
But, ANY oil filter is better than NO oil filter.

John
 
Werner,

I am a little confused by your statement in post #4, see below. Are you saying that the pump puts out 80 psi as the oil enters the filter. That is why I made the comment that the high pressure is bad for the gears. 80 psi is 80 psi whether the engine is pressure lubricated or not. It is very possible I miss understood.

"I measured the pump pressure before installing the full flow oil filter. The normal oil pump reaches >80 PSI. When the engine is warm, the pressure difference in front of and behind the filter medium is <3 PSI."
 
nkaminar said:
Werner,

I am a little confused by your statement in post #4, see below. Are you saying that the pump puts out 80 psi as the oil enters the filter. That is why I made the comment that the high pressure is bad for the gears. 80 psi is 80 psi whether the engine is pressure lubricated or not. It is very possible I miss understood.

"I measured the pump pressure before installing the full flow oil filter. The normal oil pump reaches >80 PSI. When the engine is warm, the pressure difference in front of and behind the filter medium is <3 PSI."
Click to expand...

I think Werner is refering to the pressure the pump will push if the outlet is closed. In a real life situation the outlet is basically open/unrestricted so nearly no oil pressure, just volume.
 
The oil pressure on a Model A is very low because there is virtually no restriction, which is needed to built up pressure. The full flow filter has very little restriction. If it becomes clogged there is a bypass. Use it without worry. (You mentioned that you started thinking again. When I do that it usually gets me in trouble. Particularly around the house where any thinking that needs to be done has already been taken care of, but also in the shop where I tend to over-think things. )
 
Guten Tag nKaminar.

Thanks for your response. I may have expressed myself unclearly. The written "80 PSI" is the pressure that the pump may create if the oil outlet is closed. The pump's power reaches 80 PSI.

The necessary pressure up to the filter inlet/valve chamber is very low, since only approx. 10" height has to be conveyed from the pump up to the filter chamber. That's the true oil pressure, shown by the indicator/pointer of your oil gauge. -



Again; only with pressure lubrication, the bearings of the crankshaft and connecting rods can be damaged if the oil pressure is very too high.

But that doesn't matter with the A motor because it only has a gravity lubrication, there is no pressure.
 
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