I installed a rad on my 1951 flathead which I rebuilt last winter and intend to install in my 1952 F1 and ran it for a bit last Saturday. I have the motor sitting on a cart and I have an oil pressure gauge mounted. I found that the oil pressure went lower and lower as the engine warmed up until it was almost zero at idle. It was about 15 lbs cold. When I ran it briefly a couple of weeks ago without the rad I think it was about 40 lbs but flickering a lot. I thought it might be the gauge so I installed a different one today with the same result. Is there a way to adjust the pressure to get it higher? I see the slotted head of a machine screw or bolt and what looks like a small round plate. I tried removing this but it refuses to budge despite applying some heat. I've attached a picture. Any advice on how to get a more acceptable oil pressure?
8BA Low Oil Pressure
- Thread starter Eagle43
- Start date
JSeery
Member Emeritus
What you are calling a screw is part of the block casting. There is no external adjustment for the oil pressure. What is the "to sump" marked in your photo? That should be an oil filter connection and would require a restrictor. Remove that line and install a plug in the fitting and see what your oil pressure is.
Tinker
Well-known member
Pressure sounds fine except for the flickering. Flatheads are a low pressure system. At hot idle 15lbs is fine depending on the engine your building or what it is.
As oil gets hot it will get thinner. So if you start out cold at 15 and then go to 0. Could be bearings or a bad/worn pump.
As oil gets hot it will get thinner. So if you start out cold at 15 and then go to 0. Could be bearings or a bad/worn pump.
Tinker
Well-known member
Well isn't it normal that there is only one opening there for the electronic oil pressure gauge. People drilled and tapped it for oil filters (later yrs may have both). So maybe someone plumbed this in a wild way after removing the filter?
Certainly if that "to the sump" just drops oil into the pan or valley it would lower oil pressure.
Certainly if that "to the sump" just drops oil into the pan or valley it would lower oil pressure.
51 MERC-CT
Well-known member
The line you have labeled "sump" should be going to the input side of the oil filter.
If you don't have a filter then that port should be plugged.
If you don't have a filter then that port should be plugged.
flatjack9
Well-known member
All flatheads have 2 - 1/4" pipe connections at the back of the block just as his picture shows.
jseery has it, your "sump" line needs to be plugged if no filter, not returned to the oil pan. the bypass system uses that line for the filter, but it is restricted so that real pressure is sent off to the rest of the motor. you have only run it a short bit, i would guess some oil was getting to the bearings and hopefully you are ok yet. plug it, run it, and see what you get
Tinker
Well-known member
Yes... but early fords 38 "21 bolt" back to 32 only had one. At least my early 38 only had one for the oil sensor (maybe I got the only block). I had it drilled on the off chance I might use a spinoff filter. I have plugged it.
Brian
Well-known member
Yes... but early fords 38 "21 bolt" back to 32 only had one. At least my early 38 only had one for the oil sensor (maybe I got the only block). I had it drilled on the off chance I might use a spinoff filter. I have plugged it.
Respectfully, I must question this above quote.....
Flatjack9 is correct.
Every flathead I've ever seen has two drilled and tapped holes at back of block. Some have three. You must have the only block in existence with the one hole, as you state.
Respectfully, I must question this above quote.....
Flatjack9 is correct.
Every flathead I've ever seen has two drilled and tapped holes at back of block. Some have three. You must have the only block in existence with the one hole, as you state.
19Fordy
Well-known member
Eagle43: I think you have your lines reversed in the first photo.
When I removed the oil filter from my 8BA I plugged the threaded return hole in the side of the block and also installed a plug in the horizontal hole at rear of the stock block. I then installed an 1/8 in. pipe thread vertical pipe and and mounted an oil pressure sender sender gauge to the top of that pipe with an oil pressure shut off switch lower down for my electric fuel pump. Oil pressure gauge reads 45 lbs cold and about 25 hot. Ran that for many years with no problems.
In the photo you can see the oil pressure sending unit at the top and the electric fuel pump shut off with the blue terminals attached.
When I removed the oil filter from my 8BA I plugged the threaded return hole in the side of the block and also installed a plug in the horizontal hole at rear of the stock block. I then installed an 1/8 in. pipe thread vertical pipe and and mounted an oil pressure sender sender gauge to the top of that pipe with an oil pressure shut off switch lower down for my electric fuel pump. Oil pressure gauge reads 45 lbs cold and about 25 hot. Ran that for many years with no problems.
In the photo you can see the oil pressure sending unit at the top and the electric fuel pump shut off with the blue terminals attached.
Attachments
Last edited:
Zeke3
Well-known member
The OP's engine appears to have a plug under the word "What" in the picture. You should confirm whether this engine has a grub screw installed in the oil passage where the line to the sump is plumbed. See the attached link for more discussion about the screw.
https://www.fordbarn.com/forum/showthread.php?t=272160&highlight=grub+screw
https://www.fordbarn.com/forum/showthread.php?t=272160&highlight=grub+screw
JSeery
Member Emeritus
Why would it make any difference which hole at the back of the block was used for the oil pressure sending unit, they go to the same passage!
Desoto291Hemi
Senior Member
The What is it looks like a casting mark left over from the original molds.
I have seen these many times in other engine blocks.
I am new to Flatheads ,,,,I could be wrong,,,but that is what it looks like to me .
Tommy
I have seen these many times in other engine blocks.
I am new to Flatheads ,,,,I could be wrong,,,but that is what it looks like to me .
Tommy
51 MERC-CT
Well-known member
JSeery
Member Emeritus
Good catch 51 Merc!! That needs to be checked to see if the horizonal passage is open or plugged. The horizonal passage that has the 7/16 Allen screw in it has to be open. The screw should not be there in your application! And of the two ports on the left in the diagram labeled 3/8 NPT, one should be plugged and the other used for the oil pressure sender. Does not matter which port you plug and which you use for the oil sender. The port on the right labeled oil return should be plugged as well (as it appears it already is).
I would guess the set screw is already removed and the issue is the one 3/8 port being plumbed to the sump. But it would sure be worth checking for the set screw just to be safe.
I would guess the set screw is already removed and the issue is the one 3/8 port being plumbed to the sump. But it would sure be worth checking for the set screw just to be safe.
Attachments
Last edited:
19Fordy
Well-known member
Eagle 43: Are you using the required oil restrictor fitting on the inlet line of your oil filter canister? This effects oil pressure reading. Read about it here:
https://www.fordbarn.com/forum/showthread.php?t=215241
First photo below: Special T restrictor fitting where oil enters filter canister. Oil pressure sending unit is at top of fitting.
2nd photo: "S" shaped line from block that goes to inlet restrictor fitting on canister.
3rd photo: Oil return line from bottom of canister to threaded fitting in block where oil returns to pan.
This canister came off a 1950 Mercury car.
Also, Thanks to all for the helpful input on my "reversed lines" theory. Will be interesting top see the final outcome. Hope it works out well.
https://www.fordbarn.com/forum/showthread.php?t=215241
First photo below: Special T restrictor fitting where oil enters filter canister. Oil pressure sending unit is at top of fitting.
2nd photo: "S" shaped line from block that goes to inlet restrictor fitting on canister.
3rd photo: Oil return line from bottom of canister to threaded fitting in block where oil returns to pan.
This canister came off a 1950 Mercury car.
Also, Thanks to all for the helpful input on my "reversed lines" theory. Will be interesting top see the final outcome. Hope it works out well.
Attachments
Last edited:
Desoto291Hemi
Senior Member
51Merc,
That looks much better,,,the original pic was inverted.
The third plug was hidden behind the words,,,,I thought I was losing my mind,,,lol.
isn’t the third one where the oil line should go,,,according to the diagram,,,if running a full flow filter ?
Isn’t that why the set screw is inserted into the oil passage,,to keep the oil going in the right direction ?
Tommy
That looks much better,,,the original pic was inverted.
The third plug was hidden behind the words,,,,I thought I was losing my mind,,,lol.
isn’t the third one where the oil line should go,,,according to the diagram,,,if running a full flow filter ?
Isn’t that why the set screw is inserted into the oil passage,,to keep the oil going in the right direction ?
Tommy