72 Oil Flow and Conversion

[luvndasun]

Hi,
I have a 72 and am putting a 81 3.0L into it. The car has a fender mounted oil cooler.

I read that the 72 oil T and P senosrs and gage use lower amps than the oil T and P sensors on the 3.0L. I bought the sensors used on the 72 engine. The oil T sensor was a direct bolt in on the 3.0L. The 72 oil pressure sender has much smaller threads than on the 3.0L oil P sender. In the pic, the 3.0L oil P sender is on the left. How can I install the 72 oil P sender, is an adapter/coupler availble?





Also, the 3.0L also has an oil pressure switch. The 72 does not have an oil pressure switch. Does the oil pressure switch need to be hooked up? If so, what would I wire it into.

What is the orientation of the 72 oil console oil thermostat? If I am standing at the back of the car looking into the engine compartment, should my thermostat be mounted in the coonsole with the lower and normally closed tstat opening be facing the passenger/right side of the car?

[budge96]

I doubt the amperage is significantly different to prevent the guage from reading ,I'd suggest
you use the sending unit made for the engine not your chassis.
I believe the orientation of the thermostat is correct once it reahces correct temp the spring will of course close the opposing side ,I have an extra off the car I can confirm if you like,thanks Bert

[luvndasun]

Hi Bert - could you verify the thermostat orientation? I just want to make sure. The tstat on the engine can only be installed one way. But on my oil console, it seems like I have a choice....not good.

I think that there's a problem with using the higher amp P sender unit with the lower amp Oil P gage on the dash. The higher amps of the later P sender causes the Dash gage to read high(peg), I could be wrong. I would sure like to use the later P sender. can somebody confirm if I can use this sensor and gage together?

Also, going to the Carerra Oil Cooler there are two hard lines. One line from the oil console and one line to the bottom of the 72 external oil tank. Does it matter which side of the Carerra Oil Cooler each of the lines are attached to?
Thanks.

[Grady Clay]

luvndasun,

The engine oil thermostat will install only one way – the mounting is asymmetrical.
The exact same thermostat is used in the Factory ’72-only oil filter/thermostat/pressure relief valve console.
The mounting studs should be asymmetrical.


The issue with the oil pressure sender is many-fold.
Yes, use the ’72 (’73 and earlier) sending unit. This allows your gauge to read correctly.
Your ’72 did not originally have both an oil pressure gauge and a low oil pressure warning light.
It was ‘either one or the other’.
That said, you can have your combination instrument modified with provision for the warning light.
There is a 2-terminal sending unit available and there is an extra (Sportomatic) wire available in the main harness.

There is a fitting for the crankcase (near the breather) for the smaller thread sending unit.
This is from all non-MFI engines prior to your 911. I think the same part is used on the CIS engines, including the 3.0.
I recall a fitting version that is a few mm shorter than usual.

A BIG issue is the clearance under the CIS for the sending unit.
This is why the sending unit was moved to the right cam oil line (and the smaller low oil pressure warning switch left under the CIS).
This is a non-issue with MFI and carbs.

I don’t have the answer as to how you can fit the 2-terminal sending unit under the CIS.
Perhaps the short version fitting and side directed electrical connections.
Keep in mind that the CIS air box is somewhat rubber mounted and can move about a bit.

I have never liked the oil pressure sending unit cantilevered off the small cam oil line fitting with the big (heavy) adaptor block of steel.
There was a small-thread fitting at the left cam oil line for the ’73.5 911T CIS.
This was a brake line ‘banjo’ fitting and a unique fitting for the crankcase.
I would only use this with a warning switch, not the pressure sender.



What is your front mounted cooler – original optional 911S full-fin version?
If something other, how is it plumbed?
What is the cooler?
Is there an electric fan?
How is the cooling air directed?
With a 3.0 in your ’72 you will need ‘Carrera-like’ oil cooling.
The ’81 3.0 should have the 245 mm engine cooling fan with the 80-83 mm pulley.
You can improve the cooling by replacing the 127 mm crankshaft pulley with the 134 mm version from the ’78-’79 911SC and other.


Best,
Grady

[luvndasun]

The good thing is that I am not using the CIS, so I can access the oil pressure switch and replace it with the early oil pressure sender. I am not going to use an oil pressure switch. If all it gets me is an idiot light indication on the dash, i can just look at the oil pressure gage and determine if pressure is not within the normal range.

The oil cooler that I have is a Carerra Cooler and hard lines. I had my oil console machined to accept the thermostat. Then its plumbed just like any other 72 with a fender mounted cooler.

Thanks!

[jmcn3rd]

The adapter you have imagined exists. This adapter allowed me to keep my 73.5 pressure sender on my new 3.2. I do not know it if would work on a 3.0 but it looks close.

[Roger 911]

jmcn3rd,

Where did you find that adapter? I need to do the same thing you did, i.e., install a early pressure sender on a 3.2 motor.

Thanks.
Roger