The Stovebolt Site Forums The Shop Area Engine Shop 235 spin on oil filter

What filter should be used? The old filter that came with the adapter plate has a tiny return oil hole in it and doesn’t seem like it would have enough flow. The numbers have been rubbed off so Napa can’t cross reference it. Will any same thread/gasket filter do? I ran 3/16 pressure line to it and was told by engine shop to regulate it to about 15psi outlet pressure so head would still get adequate oil supplied to it.

That flow control orfice is essential to keeping good oil pressure to the rest of the engine. A 235 bypass filter plumbing setup has nothing whatsoever to do with oiling the rocker arms- - - -that routing went out of practice with the 216 engine. A 235 dumps the filtered oil directly into the crankcase through a passageway just above the oil pan rail. If I'm setting up an engine for a spin-on filter, I use a Holley carburetor main jet as a restrictor, one with about a 1/16" diameter hole in it. Normal full flow filters are intended to pass enough oil to lubricate the whole engine, which makes them pretty good at straining out rocks, marbles, and bowling balls, but not very efficient at keeping oil clean. I'd suggest finding a spin-on Diesel fuel filter and the bracket that it fits, and using it as a bypass filter, since the media can strain out MUCH smaller particles. Any parts store worthy of the name will have fuel filters in stock for Cummins, Caterpillar, or Detroit Diesel engines.
Jerry

Greasy knuckels Some of my engines have screw-on filters mounted on just smooth angle iron hanging down where it's easy to change. They too have a 1/16 metering hole,are just over the counter filters work good.

Thank you both for the helpful responses, much appreciated.

If you can find a listing for a spin on oil filter for an American Motors Rambler inline six from the early 1960's, it had an orfice-controlled bypass filter with a 1/16" hole to restrict the oil flow through the filter. I believe the engine was a 196 cubic inch size, either flathead or overhead valve, depending on the year model. My 1960 Rambler American ran the flathead engine.
Jerry

Amsoil bypass filters have an efficiency rating of 98% @ 2 microns making the oil always look like it was just changed:

https://www.amsoil.ca/c/bypass-oil-filters/331/

Notice the restrictor built into the mount:

https://www.amsoil.ca/p/filter-mount-assembly-bk303/


Here's some mounting ideas:

Those are very clever ways to attach a filter, good pictures. I did get a filter with the small orifice from JC truck parts. For curiosity I also installed a pressure gauge to see what pressure was coming out of filter. I’ve not started rebuilt motor yet and wanted to see where the oil pressure was at and get some oil moving though system. I took the gear off an old distributor and used a socket where the rotor would sit to drive the oil pump. Main oil pressure or 35-40lbs was easily attained with drill at about half speed but shows no pressure in return line from filter. Should there be any there or am I worrying too much?

Because the return line just dumps into the sump, there should be no pressure in the return line.

Makes sense. I used 3/16 line for the filter, theory was to not take too much oil away from pressure side but still get some through filter. It ran for 50 years without any filter. Thanks for reply.

Curt B. Good pictures of ways to mount filters, not sure how to determine how much oil is actually traveling thru there at various temperatures. That aluminum plate mount looks good.

Did you do a "full flow conversion" or are you just replacing the cartridge filter? If you 're replacing the cartridge filter, the restrictor is fine. Most of your engine oil is being routed through the engine anyhow, and maybe 10% through the filter.

Even with the full flow conversion, oil is still bypassed around the filter element. Most automotive filters have a bypass valve that is set at 10 psi differential pressure.

I read an article that compares the full flow filter to the cartridge style oil filter.

The full flow spin-on style filters 92% of the oil. The cartridge style filters 87% of the oil. To me, the extra 5% isn't worth the effort to convert it. I'm sure we all follow the old rule of thumb and change our oil and filters at 3000 miles. I doubt there is any actual benefit to the conversion. The engine won't know the difference.

A full flow filter filters 100% of the oil. Once it clogs up a bit and the pressure opens the bypass valve, it filters it a little less at a time, but still 100% of the oil, eventually. A bypass filter also filters 100% of the oil, it just does it a little bit at a time, and strains out smaller particles than a full flow filter. If you have a filter of either type, you're good to go.