Technical Ideas for cool looking by-pass oil filtering on a '41 flathead

It does matter which way you plumb the filter. The outer part of the filter is what is designed to catch the partials. So the inlet to the filter is the line that goes to the series of outer holes.

The return line to the engine is the center hole that has the nipple the filter spins on.




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I think you’ll find the Hildebrand filter is full flow only and won’t work with a partial flow system.

I run an original filacoolator on my 40’s style roadster . Which isn’t correct but I think fits the style and gives me a little more insurance for my flathead investment .

Having flicked though most of the Don montgomery books there seems to be very few that run any sort of oil filters , but then most are 21 stud engines and wouldn’t have the option to run a filter from stock and why would you bother modifying the block to fit one when another motor from the scrap yard is easy as anything ?

 

Bursonaw; thanks for your last post. I have just come back from the shop and looked at the way I plumbed in the Hildebrand oil filter housing. It looks like I have everything done correctly, oil line from the block to the filter and the return line back to the block all look correct. Thanks again for your great explanation of how these filters work! The knowledge here on the HAMB is second to none!

 

A full flow oil filter will work on a bypass system. The difference is that a full flow filters in today’s standards, filters at around 20 microns. A true bypass filter, filters around 1 to 5 microns. If you use the the Hildebrant cover you can only find regular full flow filters that filter at 20 microns that will fit in the cover. The original bypass oil filter systems for the Ford flathead, filtered at 25 to 30 microns.




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Cool, learn something new every day!

 

I believe (no experience with such things!) that many seriously expensive engines like huge diesels and such use a full flow filter to keep dead rodents and lost screwdrivers out of circulation full time and a bypass filter to keep working away at the small stuff.
Parenthetically...I read an article by a NASCAR type on the familiar SBC system. He says that on near stock systems, an SBC is not really full flow at all. The bypass valve is busy when cold and at high RPM, and of course the little filter has to be pretty coarse.
The earlier system, the one use til about '69 with the big removable can over a large filter, is supposedly considerably better...seems likely, since Chevy continued to use it for years on police cars and trucks and sold the necessary parts to convert late engines.
He said that true full time filtering on a high RPM application requires dual filters and frequent changes.

 

I just used a stock Mopar bypass on the 230 in my 48 Plymouth Coupe. Thought it looked decent with just some cleanup and a couple cans of spray paint.

 

@banjorear
I have a real nice filter with a new replaceable filter inside that looks like the one above ^^^^. I'll send it to you. I was going to filter my flathead but I talked to a lot of people that said filtering, due to the loss of pressure and flow, may be more harmful than not filtering. I decided to change my oil more often and not go the filter route as previously stated. I don't have enough miles on that flathead to tell you that was the correct move. That said, I'll gladly provide my filter assembly if that is the route you wish. PM me if you are interested.

 

" due to the lack of the send/return boss"
Huh? I think this is a misunderstanding of something...unlikely that Ronnie is Rong!
I assume this means the bulge the filter is hooked to in this pic.

I think that goes all the way back, and originated to allow convenient drilling of basic oil passages!
The '46-48 bypass filter was available dealer installed before the war...it had to drain into 2 alternate places since the drain in pan wasn't there yet, but was otherwise the same. Bulge i think goes all the way back...will have to visit basement to reassure myself!
There was also an accessory throw-away bypass filter working in same type hookup about '36-7.

By the way...the basic hookup shown in this hotrod conversion was used (and probably originated in) in wartime Canadian 99 and 29 engines, feeding a cooler in tracked vehicles and a big filter in heavy trucks.
If you look in the 1946 edition of the V8 overhaul book the engine shown in many pictures is clearly a 1942 sort... has the "raised" manifold area.
Go back to the clutch section in the book and you will see that it happens to have THREE oil holes like the hotrod one shown here. It is a wartime heavy duty motor made for the desert war!
The 1942 types made from about 1943 (military motors) and the later USA civilian flatheads had a little round boss where the third hole was to be drilled for the warmotors.

 

Also... "filtering, due to the loss of pressure and flow..." Stock bypass filters blow through an .060 hole
(Flatdog experimented and concluded that this was only to keep from blowing out the lid gasket!) and would hardly affect anything. Once, on an engine also supporting the stock filter, I had a cracked oil line...until I figured that out I briefly had a max range of 25 miles before adding oil. Helluva leak and mess, but no problem with pressure as long as there was oil. Flathead pump system is pretty stout.

 

My knowledge is only borrowed @Bruce Lancaster ...but applied.
Only citing the information I obtained HandH when building that 8BA. And it is pertaining to partial bypass not full flow adaptation. I know far too little about these engines to throw down with the likes of you