Question on flathead oil canister filter housing

1948F-1Pickup

1948F-1Pickup

Well-known member
Addressing various engine items in preparation for when I get my flathead back from the builder.
Cleaning up the housing and pulled the brass fitting near the top on the side of the housing...... standard male pipe thread with inverted flare for the oil line at the other end...... TINY 1/16" clearance hole in this fitting. Is that correct?
 

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That is correct. It limits the amount of oil that is allowed to flow to the BYPASS filter. If too much were allowed to flow it would reduce the amount of oil available to flow to the bearings etc.
The restrictor must be installed between the engine outlet and the filter inlet. If installed on the outlet of the filter it puts more pressure into the filter and makes it more prone to leak.
Mart.
 
Cool. Thanks for that guys.
When I replaced the bottom fitting on the housing because of a weep at the flared portion, that one was merely a "standard" item.
I was surprised at the amount of restriction in this upper fitting......
 
They are called by-pass filters because the oil going to the filter "by-passes" the engine and is returned to the oil galley or oil pan. So, you want to limit the amount of oil by-passing the intended purpose of lubricating the engine bearings and moving parts (and also providing cooling).
 
If the center tube in the filter canister that goes thru the middle of the filter and is connected to the return line has this 1/16th hole, is that not the essential flow restrictor? Leaving the only reason to having this fitting(as pictured above) with the restrictor hole would be to reduce cannister pressure to prevent leaks?

With a restrictor hole on the inlet to reduce the flow, wouldn't that actually increase pressure in the cannister as well?
 
Will D said:
If the center tube in the filter canister that goes thru the middle of the filter and is connected to the return line has this 1/16th hole, is that not the essential flow restrictor? Leaving the only reason to having this fitting(as pictured above) with the restrictor hole would be to reduce cannister pressure to prevent leaks?

With a restrictor hole on the inlet to reduce the flow, wouldn't that actually increase pressure in the cannister as well?
Click to expand...
Every stock Ford filter I have seen has the two holes in the center tube and perhaps some early as well as aftermarket filters did not.
Probably a design change to eliminate over pressure in the canister.
 
I would always want this restrictor to be on the inlet side of the original type filter. These "drip-feed" units don't have that good of seals in the top plate or top-nut/bolt . . . too much pressure/volume, they tend to leak - all over your engine and garage floor! LOL
 
51 MERC-CT said:
Every stock Ford filter I have seen has the two holes in the center tube and perhaps some early as well as aftermarket filters did not.
Probably a design change to eliminate over pressure in the canister.
Click to expand...

Did a little researching and some reading, defies logic but makes sense. The small hole will reduce flow and pressure in the canister when installed on inlet side, interesting.
 
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