Oil pressure sending unit

[Sloggie]

Hi,

I put on some aftermarket gauges last year (i'ts nice to read oil pressure) on my 67 429.  I'd like to get an electric fuel pump and hook up and safety switch for an electric fuel pump.  Do folks think there would there be any issues if I put in some plumbing to make the fitting into 3? 

Should I be using Brass or some other material? 

[tedsled66]

I have been working on this same project myself but I am not sure about the pressure cut off switch or as how/where to install it. I wanted to keep the original red idiot light and install a pressure gauge too. I don't know of any three way connecters. If you get a brass "t" connection make sure it is high enough for the the sending unit to clear the block.

Where are your gauges mounted? I found a sweet spot under the dash and used pre-drilled screw holes to run the wires.

Tedsled

[Sloggie]

I have been working on this same project myself but I am not sure about the pressure cut off switch or as how/where to install it. I wanted to keep the original red idiot light and install a pressure gauge too. I don't know of any three way connecters. If you get a brass "t" connection make sure it is high enough for the the sending unit to clear the block.

Where are your gauges mounted? I found a sweet spot under the dash and used pre-drilled screw holes to run the wires.

Tedsled

I put the gauges under the dash.  On the 67, the Oil Pressure Sending Unit is behind the Carb.  For a 3 way connector, I woudl just get some fancy plumbing or use two Ts'

[bcroe]

There are plenty of T type fittings on my oil pressure gauge/idiot light combinations, no problem.  You can get an oil pressure switch with 2 extra terminals, to cut off the fuel pump when the engine stops (ignition still on).  I'll need to put up a picture, it keeps coming up.  Mine is a  FILKO  OP-67X    Bruce Roe

[73eldo]

Ya unlike a temperature probe that has to be in the flow to work correctly pressure is pressure so other than how ugly it will look you could in theory plumb in as many as you want.   Be sure to take into account how easily damaged things can be, you dont want to end up with a whole tree sticking out where it could be hit with something off the road or a wrench or something like that.

Good thought on leaving the light hooked up.  I have now done that on all my engines after having an oil pump failure.  With oil pressure you only have a second to react and the light will get your attention quicker so you look at the gauge.   

[Rhino]

I have used brass T fittings to do exactly what you are talking about in at least a dozen cars. I always take the pressure switch with me to make sure I get the right threads. I buy the T's at a PLUMBING supply house, always use brass and teflon tape. No problems. You can even get a manifold so you can hook up a safety switch, idiot light and gauge.

[Sloggie]

I have used brass T fittings to do exactly what you are talking about in at least a dozen cars. I always take the pressure switch with me to make sure I get the right threads. I buy the T's at a PLUMBING supply house, always use brass and teflon tape. No problems. You can even get a manifold so you can hook up a safety switch, idiot light and gauge.

Brass and teflon tape?  That I can do.  Thanks.

[73eldo]

If you have single wire electric sending units the teflon tape may screw things up because its an insulator.    Single wire senders ground through the body.  To check you can use an ohm meter with one wire to a clean grounding point and the other wire to the body of the sending unit, you should read very close to zero ohms if its making a good connection.  If you got several ohms the tape or other sealant is not letting the sensor ground. 

[guidematic]

 Liquid teflon sealer works well for me. The stuff in the tube.

 Mike

[olds34dude]

I just got a tee fiting from napa so I can have the inferior working Classic Instrument still hooked up and use a mechanical gauge on my 429 powered '37,  fitting WH 3750X2,  $3.72; to go to the mechanical line fitting WH 68X2 @$1.86.  You may want a straight fitting to elevate the whole thing, I had to put the tee on w/o the side fitting installed because the adapter plate for the 700 trans sticks up too high for clearence to screw it in assembled as one unit, don't use teflon onthe electrical part . works great Dave

[guidematic]

 A good selection of brass fittings is good to have. Many hardware stores, plumbing sores and most of all HD truck shops will carry a good selection of them.

 In my part of the trade I use them all the time. And you'd be amazed at what you can put together with them.

 Mike

[tedsled66]

So I finally wired up my sending unit and gauge under the dash and I am concerned about my oil pressure. The gauge sits at near zero while idling and only raises up to about 12-15 while on the highway. Since I should be reading 30-35p.s.i. at 30 mph and 10p.s.i. at idle I feel something is amiss. My idiot light does still work because it comes on when I am a quart to a quart and a half low and that should be at below 8p.s.i. Is there something I can do to check my gauge to see if it is working correctly or a secondary way to get a reading on oil pressure?

[The Tassie Devil (Bruce Reynolds)]

I would be suspecting a faulty gauge, or a mis-matched sender unit.

The best way to check is to get one of the el-cheapo capillary oil pressure gauges and temporarily plumb that in.   Even though they are cheap, they read pretty well.

But, if the initial readings are correct, then you have an internal problem either in the pump, or excess clearances in the bearings.

Bruce.

[73eldo]

Is this an electric gauge?   If so does it have 2 terminals or just one?  If its one then it has to ground through the adapters and such to the block.  If you used teflon tape you may not be getting a good ground. 

[tedsled66]

Is this an electric gauge?   If so does it have 2 terminals or just one?  If its one then it has to ground through the adapters and such to the block.  If you used teflon tape you may not be getting a good ground. 

Yes, it is an electric gauge with one + terminal, one ground terminal and one terminal for the backlit light which I have not connected. I don't know of what ground adapter you are referring to? I have it grounded to some steel framing under the dash. Should it be grounded else where? Thanks for the clarification.

Tedsled