"95%" oil filter pressure drop across the filter

[40cpe]

Has anyone measured the drop from the input line to the output line of the filter? The convenient location to take pressure readings is ahead of the filter.

When pre-lubing my engine I noticed about 10 # of pressure when the oil hit the filter and once it got to the engine it jumped to 50#. Makes me wonder if the running reading would be lower on the engine side of the filter. I'm considering drilling/tapping the 90 degree fitting going into the engine for my oil pressure sending line. Has anyone done it?

 

[Ronnieroadster]

I doubt there's any noticeable difference in readings before or after the filter. If you notice any pressure drop across the filter the cause is a poor filter design for this application the amount of holes around the outer ring of the filter is an area of concern I have seen some fram and AC filters with six very small holes these filters caused a long delay in seeing a reading on the oil pressure gauge. I always use Ford Motorcraft FL-1 A filters on this conversion their design has eight oval shaped holes for oil flow as well as a larger diameter center pipe which is 7/8 of an inch. Using the Motorcraft filters there's no delay in pressure readings.
So far I have a few hundred thousand miles on my 95 percent converted flatheads never experianced any lubrication issues with the proper filter and oil pump.

 

[Ronnie]

The down stream pressures in a normal running temp engine are always less than the upstream pressures.This will be observed when the oil is up to temp.This is referred to as pressure differential.The filters you mention are all very capable of fulfilling your needs.Remember all the filters out there you see in stores only have to meet the oem requirements,not exceed them.(some do both) Don't try and reinvent the system.As long as the supply lines are not reversed you will be good to go.In your statement about the center tube being larger would have nothing with pressures.The difference will always be less than the bypass valve setting for it to remain closed.I hope this helps.

R

 

[40cpe]

I do have the FL1A filter on it. Do OEM newer engines have the pressure sensor upstream or downstream of the filter? Anyone know? In a perfect world, I would rather see pressures my bearing see rather than what the filter sees.

 

[Ronnie]

Then in your final install put your gauge after the filter.As i stated at operating temp the differential pressure will be less than the bypass valve setting in order to keep the valve closed,that on average is somewhere between 7 to 12 lbs or so.

R

 

[Ronnieroadster]

The down stream pressures in a normal running temp engine are always less than the upstream pressures.This will be observed when the oil is up to temp.This is referred to as pressure differential.The filters you mention are all very capable of fulfilling your needs.Remember all the filters out there you see in stores only have to meet the oem requirements,not exceed them.(some do both) Don't try and reinvent the system.As long as the supply lines are not reversed you will be good to go.In your statement about the center tube being larger would have nothing with pressures.The difference will always be less than the bypass valve setting for it to remain closed.I hope this helps.

R

Actual experience with various filters on this conversion has shown me there is a big difference in the brand type of filter. Fords design with the larger center passage and superior design outer passages far exceed most gm type filters which have smaller inner and outer passages. Volume and flow with that you wont go wrong.

 

[40cpe]

Then in your final install put your gauge after the filter.As i stated at operating temp the differential pressure will be less than the bypass valve setting in order to keep the valve closed,that on average is somewhere between 7 to 12 lbs or so.

R

I tapped the engine fitting to see the oil pressure on the "out" side of the remote filter with a FL1A filter installed. Temp was 160/180. The present reading is 10# less than when reading from the oil pump output port.

 

[Ronnie]

There is nothing wrong with that.

Fixed that pic for the guy's

R

 

[JSeery]

I want to know the oil pressure going into the engine, not what is coming out of the pump. That said, the pressure drop across the filter is not an issue as long as adequate oil pressure is feeding the engine.

 

[Ronnieroadster]

The 90 degree fittings your using are adding a lot of flow restriction to the oil system be careful. If you have more angled fittings on the filter end there's a great deal of restriction.
I have seen the results of bearing damage caused by four 90 degree 3/8 pipe thread fittings to 1/2 inch inside diameter oil lines the two oil lines had a combined total length of just over six feet. It was not a pretty picture.

 

[40cpe]

Sorry about the picture being upside down. It was straight on the preview. Ronnie, the filter end fittings are straight. I noticed the opening at the flared connection was small, about 1/4" (6 AN fittings) but I didn't measure them. The flared hose fittings have small passages in them, too. I don't see how to get larger openings being limited to 3/8" pipe threads in the engine. I'm using hydraulic fittings and lines and that is what the hydraulic shop recommended. Is there something better for the connecting lines?

 

[Ronnieroadster]

Sorry about the picture being upside down. It was straight on the preview. Ronnie, the filter end fittings are straight. I noticed the opening at the flared connection was small, about 1/4" (6 AN fittings) but I didn't measure them. The flared hose fittings have small passages in them, too. I don't see how to get larger openings being limited to 3/8" pipe threads in the engine. I'm using hydraulic fittings and lines and that is what the hydraulic shop recommended. Is there something better for the connecting lines?

Heres what I use which I feel would be much better for flow.
For fittigns I use barb type brass that have 3/8 pipe threads they are flared but they have an ID of .375 which I then open up to 421. This slight increase in size will not hurt the flare design for sealing. That .421 diameter is the size of the cross oil passage in the flathead block. This way there's no added restriction to at least what Ford designed for the passage in the block. The hose end of the fitting is for 1/2 inch ID hose.
I get all my fittings from Mc master Carr they are barbed for press on hose. The hose I use is from Aero Quip which is also avalible from Mcmaster its blue in color or black. The hose is good for 150 psi. The fittings and hose are common in the hydraulic field. Using these parts I make up the hose to whatever length I need myself.

 

[Bored&Stroked]

If you're going to need/use 45 or 90 degree fittings, then buy the high-flow versions that are designed for performance oiling systems. The fittings are not cheap, but they restrict the flow the least amount possible.

Here is the type of fitting I purchased from Jegs:



Here is an example on a 100% full-flow setup that I built (hidden inside of a Fram filter). I used -10 hoses as I wanted to minimize the restriction through the system. I also increased the oil fitting sizes on the back of the block to 3/8" NPT and used a 7/16 drill to bore-out the main horizontal oil return passage back into the block.

 

[Ol' Ron]

My new remote filter has a gauge output on the engine side of the filter. I have an oil gauge in the glove box with a small gauge for the oil and temp as backup.

 

[Ronnie]

I don't see a problem with 10 lb difference in pressure.
What is pressure before filter and after? Also what are the pressures at start up cold engine?

R

 

[mike42]

You know it's funny.....when I was a kid and had a 1950 Ford. I just started it up Summer or Winter and ran the hell of of it. Never a problem. Now we are all worried about so many different things and nursing these flatheads along ! It makes me chuckle....!

 

[JSeery]

You know it's funny.....when I was a kid and had a 1950 Ford. I just started it up Summer or Winter and ran the hell of of it. Never a problem. Now we are all worried about so many different things and nursing these flatheads along ! It makes me chuckle....!

I agree! BUT, it is a little more difficult to fix a screwup these days. Had a grandfather that told me he never maintained or fixed anything on the old Fords. He drove them until there was some issue then got rid of that one and got a replacement. Not that easy now days.

 

[40cpe]

It looks like I'm buying and education. I have 3/8" ID hose and it looks like Ronnie uses 1/2" and Bored & Stroked uses 5/8". I found 3/8 pipe to -8 fitting. I'll get everything mounted and then buy larger fittings and hoses.

The pressure ahead of the filter was 55# and 45#on the engine side with 10w-30 oil. The temp was 170 average between the two sides but the oil wasn't that warm. I'm TRYING not to run the engine until I get it in the car.

 

[BillM]

It looks like I'm buying and education. I have 3/8" ID hose and it looks like Ronnie uses 1/2" and Bored & Stroked uses 5/8". I found 3/8 pipe to -8 fitting. I'll get everything mounted and then buy larger fittings and hoses.

The pressure ahead of the filter was 55# and 45#on the engine side with 10w-30 oil. The temp was 170 average between the two sides but the oil wasn't that warm. I'm TRYING not to run the engine until I get it in the car.

It would be interesting to see the pressures after you change the fittings and hoses.

 

[40cpe]

I measured the ID if the -6 fittings I have, it is .271. The rear main already has it's oil, so the filtered oil goes straight to the valley tube, less what is lost at the fuel pump rod. I just checked the diameter of the valley tube and it is about 23/64. These fittings won't deliver all the volume a loose engine could use, I don't think.