I’m installing an oil pressure sensor into flathead. I have 3 possible ports it sure which to use. Please see picture if someone could help.

 

Really, any of the three. It is usually in the middle one.

Yours must be a Canadian engine. Or military.

Edit: Has your engine been started and run, without an oil filter or oil gauge?

 

On a '51, I believe the OP sender goes in a fitting at the filter, but with yours being Canadian I can't sweat to that being the case.

I would make sure your engine isn't set up for the full-flow Canadian filter system. Pull all 3 of the plugs and make sure a wire inserted in the horizontal hole can be seen in both of the vertical holes.

 

Yes it is Canadian. Nope has not been run. I will be running the speedway beehive filter on it.
ok will in cap all three to see if they are in a common hole

 

Why I asked if it had been run, and Ross suggested you check for the plug:

You may already know this, but if it has the plug (grub screw), shown in the red box below, you cannot run it without a filter, or at least a bypass tube. The front 3/4 of the engine won't get oil.

An entry on the H.A.M.B. from a guy that didn't know: Think Im going to be sick. brand new flathead siezed. | Page 5 | The H.A.M.B. (jalopyjournal.com)

The filter has to be a high-flow type, not the original.



Our U.S. built flatheads use a "bypass" filter system where only a small percentage of the oil actually goes through the filter at a time. We don't have the third plug, the one on the far right above. The Canadian built flatheads can send nearly all of the oil (I think it's 90-something %) through the filter. With that plug removed, it can use the same bypass system as ours, or no filter at all.

There is a history to this, something about high-stress engines and WWII, but I don't know the whole story. It may actually be somewhere in the H.A.M.B. thread above. I had it book-marked but it's been a few years since I actually read it.

 

Nope I didn’t know any of this. Just so I don’t mess it up. I plan on using a remote oil filter. Picture attached. Do I want the grub screw in or out. Seems if it out then oil goes right straight back into filter and n’ont engine. Or am I reading picture wrong.

 

To be clear, Ken's diagram above is for a Full-Flow type filter. The beehive is still a bypass filter, not a full-flow. You DON'T want a grub screw, all passages should be open to each other. The beehive has a restrictor orifice in the filter assembly itself, to limit flow to the filter. As stated, the line to the filter is usually on the center port, but can be on any of them. You could put a Tee in the line to the filter for the OP sender. The return line from the filter goes to a port on the lower block, below the dipstick tube.

 

Can I just plumb. it like what is in the red box couple photos above. Having sensor in top one and the one far right for the return and the horizontal one for flow to filter.
or are you saying I use the top left one and plomb oil recover into it and ignore the top far right one.
also how do I get that worm screw out. Is it threaded in there and I unscrew it.
i really don’t want to screw this up. So want to fully understand it.
will this be a good enough filtering system.

 

First thing to do is find out if there is a grub screw in there. I doubt it, since it is a Canadian engine it likely had the system I posted in Post #3 above. It doesn't use a grub screw, it uses special fittings that accomplish the same thing. After you check for a grub screw, check for the port on the lower block for a return fitting (it may have a pipe plug in it, or not even be there). If there isn't a return port on the block, you will need to get the special fittings shown in #3 above and get a full-flow remote filter (not necessarily the original kind, many people sell them).

A bypass system filters ~10% of the oil coming out of the pump, with a much finer filter than a full-flow element, and returns the cleaned oil to the oil pan. A bypass element can't pass enough oil to be used in a full-flow system. The bypass system obviously won't filter all the oil going to the bearings, but it eventually filters all the oil and gets it much cleaner than a full-flow. Your beehive filter can only be used in a bypass system.

You can't plumb the beehive like is shown in the red box. You go from one of the 3 ports to the bottom of the beehive, and plumb the outlet of the beehive to the port on the lower block (which dumps the oil back into the oil pan). Put the OP sender in any of the other 3 ports. BUT make sure you don't have a grub screw FIRST!

PS -- when you pull the plugs to check for the grub screw, post a picture of them please

 

Ok
had to go check. I pulled all three plugs. Picture from left to right. Large one is from top left input. Plastic red one is center one, I’m sure this is temp plug from builder. The one with square head is from horizontal input. I ran a wire through top left port and out horizontal one. So thinking no worm screw.
the lower block plug is a brass one into original threaded hole
so am thinking this. Let me know what you think.

outflow from my beehive to top left port. Center port oil sensor. Horizontal one remains plugged. Inflow to beehive from brass port on lower block

is that all I will need to safely run engine.

 

You've got it backwards: oil flow is out of the 3 ports, Supply from one of them to the bottom of the beehive; Return from the side of the beehive to the hole on the lower side of the block. Sender fits best in the center vertical port, I'd guess.

On a stock system, the lines have flare fittings like brake lines, and there are adapter fittings with pipe thread to fit the block and filter. I would hope your beehive came with instructions.

I just noticed that your engine has studs/nuts for the heads, instead of bolts like the typical 8BA. Can you post a picture of the driver's side cylinder head?

 

Ah. Ok. I have seen pre made oil lines with proper NPT fittings on line. I do need another one of the port nuts on the head. Really hard to find. Any idea where to look.

Attached is drivers side head.

 

I'm not sure what you mean by a "port nut"? Are you talking about the port covered with tape in the picture?

Interesting that you have Merc heads; did you have the engine rebuilt? Is it really a Merc, or just has Merc heads? I don't know why it would have studs unless that was a Canadian thing, or someone changed to them.

 

Yes, the port that has tape over it .. looking to get a nut like the one just to the right on the other port.
As for the engine. I am in Canada, this is a Mecury pick up. The engine was rebuilt when i got it, unfortunately the person who did it passed away, and i got the vehicle partially restored from the family, who would not provide any information. Initially i was going to replace the heads, but i have decided to keep them as a bit different....not keen on the colour, but that was the colour....the only thing i am doing is switching to 12 volts and going to dual carbs....

 

Mercury trucks didn't come with Mercury (255 c.i.) engines, they came with Ford engines (239 c.i.). Entirely possible someone put a Merc engine in your truck, also possible someone put Merc heads on a Ford engine. Merc heads have larger combustion chambers, so if put on a Ford engine, it actually lowers the compression ratio a decent amount.

The port you are asking about is the location for the temperature sender.