I am installing a mechanical oil pressure gauge with a T-piece so I can also plug in the oil light sender.

The hole at the front of the block in my motor where the oil light sender normally plugs in has been blocked.

I have noticed that the block has another hole at the back just under the drivers side side cover with a bolt in it that has the same thread dimensions as the oil-line T-piece.

I'm pretty sure this hole can be used for the oil pressure T-piece but would like to know if anyone else has done this or seen this setup before.?

Here's a photo of the hole at the back of the block (bolt removed) and also of the T-piece that I want to screw in and the bolt that came out of the hole;

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Your imagination is only limited by the size of your wallet
"61 850 original and crusty (Mavis)
"64 Smooth Roof Van (Colin)
"67 Deluxe resto project (Monty)

NO
That is a vac connection on the intake side of the pump.

Put a tee into the oil pressure sender hole on the front of the block.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I'm glad I asked !!
Thanks again Doc, that could have been a disaster.
I'll remove the plug at the front and attach the oil T-piece there.
What is the vacuum connection for?

_________________
Your imagination is only limited by the size of your wallet
"61 850 original and crusty (Mavis)
"64 Smooth Roof Van (Colin)
"67 Deluxe resto project (Monty)

would be a handy spot for pressure priming the oil pump, but I do it from the oil pressure outlet on the front of the block... I always have oil pressure right up to the rockers before hitting the starter on a motor for the first time

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Not real good for priming the pump, it'll tend to just run down the BIG suction drilling and back into the sump.
Best spot to prime the pump is the banjo bolt on front of block. This puts a head of oil above the pump, then turn engine backwards a turn or two.
Don't prime using the relief valve hole, it is too low.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Is that hole at the back of the block anything to do with a PCV system (ie, attach a hose from there to a catch can and then back into the inlet manifold via a PCV valve)?

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Your imagination is only limited by the size of your wallet
"61 850 original and crusty (Mavis)
"64 Smooth Roof Van (Colin)
"67 Deluxe resto project (Monty)

No, it goes into the oil pickup gallery between the oil pickup strainer and the pump. It need to be SEALED.
If air or fumes get in there you will have NO oil pressure.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

That settles it then, the bolt and copper washer go back in and won't be moved again.
Thanks Doc

_________________
Your imagination is only limited by the size of your wallet
"61 850 original and crusty (Mavis)
"64 Smooth Roof Van (Colin)
"67 Deluxe resto project (Monty)

That gallery plug at the back is where the dry sump feed goes in!

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The formula for the length of a piece of string is simple: Twice as long as from one end to the centre!