Wiring diagram for 3.0 SC engine in 1972 911 Coupé

[jsoderbe]

Hi Guys,

I have to be a crappy search-engine-user, since I couldn't find any good posts going through a 3,0 SC install in an early 911. I know a lot of you have done it already! I have found a few conversions changing to Weber's, but I decided to stick with the CIS for now.

I have a really nice 1983 204 HP 3.0 SC engine on the engine stand, going into my 1972 911 T coupé RS-clone. I think I have all the hardware and stuff to make it, backdated the exhaust, backdated the oil lines, and are about to merge together the engine and 1972 gearbox. So, that part should be ok, but I have no idea about the electric part.

I have the wiring diagrams, so I might be able to do the connections even though it would be easier if someone had a conversion diagram. To actually find the physical wire is and where to ut it is another thing. Do I have to change the tachometer?

Anyone who had made a writeup about this? Would be great....


Johan

[jsoderbe]

Hi, this is the beauty going in:


I had to "massage" the heat exchanger to be able to fit it, since it rubbed against the oil cooler.


This is what's left of the 14-pin contact, and this is my main concern. This must work together with the contact to the left in the engine compartment.


This one should be to the CDI box, but the other one I am not sure of. Fuel pump?



Please let me know if you have any information that might save me some work.


Johan

[Flat6pac]

You have more information wire coming off the 3.0 than the body is capable of using, There is 2 wires for oil pressure, you ll use only the variable guage and it needs to be a 0-10 atm sending unit to match the guage vs the 0-5 atm of the 3.0,
Yhe temp unit on the engine has to be changed to the 901 brass sending unit vs the chrome 911 part number.
The chassis harness contains the tach drive wire so you have to pull the purple.black tach wire off the engine 14 prong connector and jump it over to the chassis harness.
The chassis harness has the red wire powering the CD 3 prong and you have to tap that into the 6 prong unit to power the CD.
Hope this is some help, its off the top of my head but most of the 14 connector goes into the chassis as designed and meets the necessary info wires.

Bruce

[jsoderbe]

Thanks Bruce!

I found another interesting thing, while mating the 3,0 with my 1972 915 gearbox. The 1972 starter only has the large plus cable and one connector. The engine wiring harness from the 3,0 has the plus cable and TWO more wires. Does that mean I have to change the starter to a newer version?

Thanks,

Johan

[jsoderbe]

So, now I think all things are in order. I switched to a newer starter, changed the temp sender unit (even though they looked the same) and changed the oil pressure sender unit to a 10 bar one.

I think I will put it back in the car now, and sort out the electric part after that. I have to switch fuel pump too, but I will do all of it then. The car has been stored for so long I actually plan to switch even the fuel tank and clean out the whole fuel system.

I'm sure I will ask some more question once it is back in the car!


Thanks,

Johan

[Flat6pac]

You need a brass colored oil temp sensor with a 901 part number on it.
The trans will be too fast for that much power, try to find a 75.
With the engine in you need the larger rear bars to hold the extra weight. 25 or 26mm bars will level you well.
Bruce

[jsoderbe]

Thanks Bruce,

It's a brass one from the 72 2,4 T enginge, but the 3,0 had a brass one already. Couldn't find the part number on the 72 one, unfortunately. Will the reading be all wrong if it is the wrong one?

I kind of like the 7:31 gear box, I think I'll give it a try. And your right, I have a set of turbo bars to handle the alu engine. It is H E A V Y, me and a friend lifted it into the truck and I had back pain for a week after....

Regards,

Johan


Thanks,

Johan

[jsoderbe]

Ok, now it's time to sort out the connectors. Now I have compared the different 14 pin in the chassis and for the engine:

Chassis:
Pin 1,
Pin 1, yellow, starter solenoid
Pin 3, black, oil temp
Pin 4, green/red, oil press indicator
Pin 7, red/black, solenoid valve
Pin 8, grey/red, oil press switch?
Pin 9, black/purple, tach signal

The rest seems to be connected to the alternator.



Engine:
Pin 1, yellow, starter solenoid
Pin 3, green/black, oil temp
Pin 4, green/red, oil press sensor
Pin 9, green/white, oil press switch
Pin 10, red/white (WUR?)
Pin 11, blue, alternator light
Pin 12, black/violet, tach signal
Pin 13, heater ventilator (removed by me)

So, have I got these right? Can I just switch the ones that I need, and drop the alternator ones from the chassis? How about the WUR pin for the engine harness?



Regards,

Johan

[jsoderbe]

So, I found this in another thread, an it supports my previous guess:

1. yellow starter solenoid
2. no wire connected
3. grn/blk oil temperature sensor
4. grn/red oil pressure sensor (for oil pressure indicator)
5. grn/yel Backup light switch
6. grey Backup light switch
7. no wire connected.
8. no wire connected
9. grn/wht oil pressure switch (for idiot light)
10. red/wht power for WUR, temperature valve, supplementary air valve
11. blu (x2) from” D+” terminals on regulator and generator
12. blk/vio from ignition box, to tach (tach signal)
13. yel/blk heater fan motor power
14. red generator output.



So, now I got it running right, and I just have to sort the last few things.

The good:
- The starter works great
- The engine is running smoothly
- The generator is charging, and the generator light is working
- Oil pressure indicator gauge is working

The bad:
- Tach is not working (still have the 1972 carb tacho installed)
- Don't believe the oil temp is working (not sure though, have not been driving on the road yet. I switched to the 901 brass sending unit.)
- Can't verify that the WUR is working, is pin #10 just 12V power? If so I can just bridge power to that pin.


Anyone that want to help me with the last outstanding questions?



Thanks,

Johan

[jsoderbe]

Now it's starting to look and drive as finished. I'm going to do a write-up when it is finished, if someone else is going down this road.

One thiing that is quite annoying is the oil temp. I only get it up to 70 degrees celsius, which is around 160 degrees fahrenheit. It seems to low, even though I switched to the 901 brass unit. Are there different versions of the 901 unit, so I might have taken the wrong one?

Reason I ask is that the engine feels a lot warmer than 160 degrees. A guess would be that is should show around 200 degrees fahrenheit.

Anyone?


Thanks,

Johan

[Dekens]

Do you allready have any news on how to solve the problem with the 1972 tacho that is not working?
We are doing the same conversion on a 1972 car... but we changed the K-jetronic by Weber carbs...

[jsoderbe]

Hi,

the tacho is not working because of the 6 pin CDI box, as far as I understand. I used an 1976 2.7 K-Jet tacho, and it works great.

I believe you have to switch the ignition parts too if you want to keep your 1972 tacho.


Thanks,

Johan

[Dekens]

And if we change the 1972 tacho by a 3.0SC tacho? Would that work?

[jsoderbe]

Hi, if you have the ignition system from the 3,0 SC engine, meaning distributor and 6 pin CDI box, then it should work. Make sure the tach wire is on the right place in the 14 pin connector.

Thanks,

Johan

[Flat6pac]

Your tach wire has to be jumped out of the 14 prong connector from the engine and outside the 14 prong connector jumped over with separate wire to the chassis harness under the fuel filter console.
The tach will run

[Sweendk]

So, here we are 10 years after the original posts: I'm finding them very useful on my quest to install a '79 CIS 3.0 into my '71 T chassis.
Thank you for posting!
PS: would love to get original colored wiring diagrams. Source?

[timmy2]

78/79

https://www.dropbox.com/s/yjfoxfvwlci6lys/911_electrical_78SC_USA.pdf?dl=0

70 (basically same as 71 for what you are doing)

https://www.dropbox.com/s/32266dstkfqnwrx/SL35-Master.pdf?dl=0

[Sweendk]

Dennis,
Thank you so much! These are MUCH nicer than the scans I had.
Also, I'll be getting back to re a replacement engine harness for the SC engine. Mine has some mice damage..
Regards,
Kirk

[l_turn9]

Don't know if you need this anymore but it's a good detailed map of the 14 point connector.


Enjoy -

[Walt Fricke]

Left Turn - that's a great diagram, I've saved it. It's for a 2.7. The 3.0s have a couple of the 14 pin connections on different pins (I went through that when swapping a 2.7 for a 3.0 in a 2.7 tub). Is there such a diagram for the 3.0s? Some source for whatever the eqrlier models, or the 3.2 and 3.6 motors used?