The Stovebolt Site Forums The Shop Area Engine Shop Full pressure oil system

Hello, so I purchased this 235 engine which had this spin on oil system. He claimed that the engine rebuild shop "Drilled/tapped" some ports and passages which made this system full pressure? I understand how the old cartridge style systems worked but not the full pressure modification. Based on the photos of the ports and locations does any of this setup make sense? Thank you

Makes no sense to me. It looks like a full flow bypass system that will lower the oil pressure dangerously.

George

It is very possible. And yours looks like it may have been.

One sure way to check is to pull the pan. If the oil output from the filter is dumping directly into the pan, then it is not full flow. But, from the location of that fitting, it looks to have been modified so it might be a full flow system. If it turns out it’s not a full flow system, those lines are way too big and are robbing you of needed oil pressure.

Here is how it’s done in this Legacy Tech Tip: 235/261 Pressure Oiling.

If the conversion of the oil galleries has been done properly, it will work, but i see some potentially fatal mistakes in the plumbing. Using flex hoses and heater hose clamps to carry full oil pressure is like drawing to an inside straight in a poker game. I'd re-plumb the system with 1/2" outside diameter metal tubing, or possibly #8 single braid hydraulic lines with flare fittings, and DO NOT use hose clamps anywhere. If the oil galleries have been plugged and re-drilled correctly, the oil pressure should be coming from the lower forward port, going through the spin-on filter, and re-entering the engine at the main oil gallery- - - -the rear, upper fitting. That flow is backwards to the way it's done with a bypass filter. It's easy to check- - - -remove the line from the lower port, put a hose into a catch container, and spin the starter with the spark plugs removed. You should get a BIG flow of oil as soon as the oil pump primes itself.
Jerry

There is a Tech Tip right here on the 'bolt for modifications to add a full flow oil filter.l

I just change mine every 3,000 miles. no filter or recirculator.

Excellent info guys. I need to be sure it's correct. Thanks again

It appears to me that this is set up to be a full-flow filter. You can see a fitting welded or braised to the right of the bypass filter dump fitting. That is the outlet from the pump that normally connects to the main oil gallery. Now the main oil gallery is fed by the hose coming from the filter to the fitting that used to feed the bypass filter.

I set up a late-block 261 for a full flow filter last summer and remember well the associated hassles. And that had the factory plug that provided for that option. If one does such a modification, 1/2", braided-steel lines, not 3/8", and AN fittings are the way to go and don't buy cheap ones. They leak. Shield whatever lines you use from exhaust heat if it's going to be in truck service. I'm not sure it was worth the trouble. I now have a Franz toilet paper filter besides the full flow as the micron size of available full-flow filters it pretty big. A good one with small pores it the Wix 51515. it's taller than most with low pressure drop.

It probably wasn't.

I read an article in Auto Restorer magazine some years back comparing canister type oil filters and modern, screw-on filters.

The canister type filtered 87% of the oil and the screw on type filtered 92% in the same measured time frame. The extra 5% isn't worth worrying about.

The exhaust heat/flex hose problem can be solved by using a 6 inch pipe nipple threaded into the block to move the flex hoses past the pipe. You could even use braided heat shield wrap like some guys use on the exhaust pipes on "bobber" motorcycles on the oil line extender pipes.
Jerry