The Stovebolt Site Forums The Shop Area Engine Shop 235 full pressure conversion

Does anyone know why on a 235 full oil pressure conversion,the diagram on the tech tips section, does not use the original hole from the engine to the filter. It would be the hole with the oil pump under it in step 2. Also in step 2 if you do not use the old hole do you have to angle the new hole to the left to intersect it. If not is that just an open rail that runs dow the side of the engine?

Yes I found I had to angle the supply hole slightly and it sits between ribs. Remember, you are blocking the supply to the oil galley in the block between the pump and galley, it takes a long 1/8" npt tap that I had problems locating to go up in the block to add the plug. Large 3/8 npt tap is to supply enough oil volumn to filter and back to oil galley. I got my lines filter base etc. fom Speedway motors. Had to go to a machine shop supply & order the long tap. I would think you could enlarge any existing galley hole for the return. Good luck with yours Zeke

There is a more detailed explanation of the full-flow conversion at Inliners tech tips and also a GMC diagram which is quite different (easier) than the 235.

Thanks for the info, but I am still wondering why you can not use the original hole there. Is it just not big enough to spread to a 3/8 or what?

Somebody with some knowledge of fluid dynamics can probably explain this better than me, but going from a 1/8" NPT fitting to a 3/8 line would rob the oil flow - plenty of pressure but restricted volume. You don't want anything to interrupt flow of oil to the bearings. When GM designed the 261 remote full-flow system they made the fittings larger, because the spin-on elements flow a lot more oil than the bypass system was designed for.

Sixpack, I am on the same track as you with the diameters, but my question is about opening the 1/8" factory hole to 3/8"? I want to know if this can or can't be done.

Codman, yes, the original 1/8 npt hole in the main oil galley can be drilled and tapped to 3/8 npt.Then use a tee screw up close for the guage or sender becomes the feed from the filter to the block. You can also go in the front near the timing cover where the galley plug is.These conversions are nothing new guys did them 30 years ago.Did one different once,never had even seen the insides of a 235 before that .The block was assembled,needed to keep the drilling mess to a minimum.I removed the curved line from the oil pump,plugged the hole in the block . Then 1/4 brass pipe was used to extend the pump outlet through the side of the oil pan. The original steel tube is 3/8 ID, same a 1/4 pipe.A coupling just inside the pan allows unscrewing the nipple if the pan ever needed removal.A home made washer and O ring seals the hole.Then I drilled and tapped the original oil galley port to 3/8 pipe.Then used adapters to go to 1/2 od rubber hose.This engine 7 years later is now in our 2 ton truck.
Ok, just for you guys I crawled under the 45 2 ton to get photos of the oil galley hole tapped to 3/8 pipe, the hose nipple is also handy for throttle return spring anchoring point, heat shield on the pipe to protect the hose.... 235 side view .. this second photo shows my through the pan job... oil pan
You should avoid the use of sharp 90 degree elbows like I used here due to clearance problems.Each elbow reduces pressure by a few psi.Man, that gas welded exhaust pipe looks a little sloppy,close your eyes if your anal about such stuff,lol.

Tony, thanks alot man. That is exactly the answer I was looking for. You are exactly on the same track that I am. I really like the idea about coming out the side of the oil pan, and with a little creativity I think I can improve the already excellent idea. I appreciate everyone's info, and it's guys like all of you that keep me from having to use a mechanic.