Large Combo Gauge Swap Questions

[1968DT]

I want to use a "S" or "L" combo gauge with temp/pressure in place of a standard temp/brake gauge. Is all needed wiring in place already? Do I just swap out. I assume the temp / pressure sensors may need to be changed out and the gauge calibrated. Is this straight forward, am I missing anything here?

Reason being for this is I will be running a higher compression engine.

[lorenzom]

Assuming you are using the correct era oil temp sensor, this is a direct swap. New oil pressure sensors will plug into the system just fine. BTW, the top 'idiot light' in the right gauge is for your handbrake warning light and is yellow.

Existing wiring harness has three wires into the engine bay for oil: one for temp, one for pressure, and one for oil level.

There is another wire, buried in the harness, that was used for the Sporto oil temp switch (located at the top of the bell housing, on the starter's side of the engine compartment seal) that might be used for an oil pressure 'idiot light' if you desire.

I just did this exchange on my '69 912...

[1968DT]

Good to know, thanks. With a 912, did you upgrade your original gauge or locate one with temp/pressure to do the swap?

[JPM]

Assuming you are using the correct era oil temp sensor, this is a direct swap. New oil pressure sensors will plug into the system just fine. BTW, the top 'idiot light' in the right gauge is for your handbrake warning light and is yellow.

Existing wiring harness has three wires into the engine bay for oil: one for temp, one for pressure, and one for oil level.

There is another wire, buried in the harness, that was used for the Sporto oil temp switch (located at the top of the bell housing, on the starter's side of the engine compartment seal) that might be used for an oil pressure 'idiot light' if you desire.

I just did this exchange on my '69 912...

Taking this one step further, where does the oil pressure "idiot light" show up since on the large combo temp/press gauge the top light is for handbrake and the bottom is the alternator light. The green oil pressure light only shows up on the standard temp/brake gauge so the wiring is in there somewhere. I am swapping a 2.4L engine (into my '69 911) which has provision for an oil pressure switch. My question is do I need a new combo gauge which has the oil pressure idiot light instead of the handbrake light and secondly where does the handbrake light go then.

[Phil Planck]

http://www.stoddard.com/90174155102.html

Is this the correct sender for both pressure and idiot light on same gauge?
Seems there would be 2 connections at the sender.

[Jim Breazeale]

Taking this one step further, where does the oil pressure "idiot light" show up since on the large combo temp/press gauge the top light is for handbrake and the bottom is the alternator light. The green oil pressure light only shows up on the standard temp/brake gauge so the wiring is in there somewhere. I am swapping a 2.4L engine (into my '69 911) which has provision for an oil pressure switch. My question is do I need a new combo gauge which has the oil pressure idiot light instead of the handbrake light and secondly where does the handbrake light go then.

There is no idiot light on a period correct oil temp/pressure gauge. You are swapping the idiot light for a pressure gauge. The idiot light wiring will be used for the pressure gauge. You just need to change the idiot light sender to a pressure sender (www.stoddard.com/90174155102.html)

Regards

Jim

[Jim Breazeale]

http://www.stoddard.com/90174155102.html

Is this the correct sender for both pressure and idiot light on same gauge?
Seems there would be 2 connections at the sender.

Yes, that is the correct sender. 74 and later 911s do come with both a idiot light and a pressure gauge. They use 2 separate senders.

Ciao

Jim

[Phil Planck]

Jim
I have to buy 2 of the above senders for the gauge you sent me? Or, 1 of above plus old blue light sender?

[Jim Breazeale]

Jim
I have to buy 2 of the above senders for the gauge you sent me? Or, 1 of above plus old blue light sender?

Phil

I don't remember what year gauge I sent you. There should be a date stamp on it or better yet, post a picture. The idiot light sender is simply a on/off switch and is cheap. You should already have that one, though.. The pressure sender isn't quite as cheap.

Regards

Jim

[JPM]

There is no idiot light on a period correct oil temp/pressure gauge. You are swapping the idiot light for a pressure gauge. The idiot light wiring will be used for the pressure gauge. You just need to change the idiot light sender to a pressure sender (www.stoddard.com/90174155102.html)

Regards

Jim

Thanks Jim, this helps clear up the question about what happened to the idiot light wiring. I found on Pelican that you can get a two pole oil pressure sender VDO-360023 with one pole for use with green light on gauge. That is an advantage over having two senders in separate locations on the case. I looked into getting a post '74 3 light gauge like the 911.641.104.29 but other than the considerable expense, there is no solution to getting an extra wire to the idiot light. So for now I plan to operate just one pole with my two light gauge.
http://www.pelicanparts.com/cgi-bin/...ressure+sender