Technical flat head ford V8 oil pressure.

Removed original ford canister oil filter set up on my 46 ford. I removed it because i did not like the look of it, and i change my oil every 12 months, I do not drive the car much as i have other cars as well.
Only travel 500 - 800 miles a year. before removal oil pressure was 45-50 psi @ 2500 rpm now it is 70-75 psi @ 2500 rpm. I use 20/50 oil, is this too much pressure ?? It has a mellings M-15 oil pump. Should i join the 2 hoses together that ran to the filter to drop the pressure back down or just leave it ?

 

Change to 10-30 and see what the pressure is after the change. Has the engine been rebuilt?

 

Karl, post this over on The Ford Barn & you'll get the info you need. Good luck. Love your avatar.

 

You can put a plug in the block where the oil line comes out, and put a plug the hole going into oil pan.

 

What route does the oil take after it leaves the canister normally?
On the early Cads it drains back to the crankcase via the timing chain area after it leaves the filter for lubing that area.
Their canister has a restrictor/orifice in the fitting on the input side which restricts flow of the oil through the filter and keeps the pressure constant in the system,then flows through the filter,draining via the above and back to the sump.It is only bleeding off and filtering a small amount of oil going through the system ,hence the need for the orifice.
If you have simply plugged off the lines and they have the same system there’s possibly where your pressure build up is.
Just a thought.

 

Barrelnose has it. If your flathead has the original style filtering system it only filters some of the oil and then it simply drains back into the pan through that hole in the block and yes, there is a small orifice it drains through to keep the pressure up. This is why if you are building a performance flathead you go through all the efforts to convert to a full flow system like the guys at H&H do. Don't connect the two lines together, simply plug the inlet to the filter that is in the block. You have now eliminated the constant hole in the oil system that is the orifice and your oil pressure will rise because of it. A full flow system is of course better but it involves drilling and tapping a new hole and plugging another and that all should be done when the block is disassembled for rebuild. The question is: Is it always necessary, I don't think so. Our oil today is so much better at keeping things clean and that combined with much more frequent oil changes means the oil and the engine are probably better off than ever. Would I do the full flow when building the engine, absolutely? In your case drive the wheels off of it and change the oil whenever you have the urge every thousand or so.

 

Why not just put the original partial flow oil filter back on, it's better than no filter. Or if it's just the looks that bother you, get a bee hive filter to replace it. It's traditional.

 

Are you using the gauge on the dash? install a mechanical gauge to get the correct pressure

 

Are those readings hot or cold? Mine drops substantially when it heats up.

I have a bypass filter with the 1/16"restriction. The output hose will fill a mason jar in about 30 seconds at idle. It won't stop a catastrophic failure from getting to the bearings but it no doubt filters the oil well.

 

70 to 75 psi is getting too high for the old bearings. Its more about sufficient flow that total pressure. I would be wanting to put a modern mechanical gauge on to get a base line number .

 

Thanks for all your replies, this reading is cold. I plan to take car for a run on sunday to see what it is hot.
I disconnected oil lines from back of block where sender unit is and plugged T fitting. Return line went into front of timing case via one of the distributor mounting bolts. Bolt has an orifice about 1/16 inch, do i need to keep oil going into timing case for lube or is it simply a drain back to sump ?

 

It is only a drain.