81 engine into a 77S.. extra cables/connectors.

teveo · teveo's Garage

Hi there, I am putting a US 1981 engine into my US 1977 911.

The cabling changed somewhat betwen these models, eg my 77 only have one of the large rectangular connectors. What is the common sense, reroute the 1981 engines cables or put the 1977 cables on the 1981 engine before installing the engine?

Any suggestions very welcome.

Flat6pac · 03-18-2009, 01:00 PM

The 81 has a Llambda system that has to be installed and plugged in of thats the large rectangular connectors youre talking about. Plugs on the front of the engine to the interior.
The other 14 prong connevtor in the left rear is mostly standard evcept you have to pull the purple/black tach wire out of the connector and jump it to the chassis harness under the CD box, there is a T 2 wire connector
You need the the 6prong cdbox too

Bruce

teveo · teveo's Garage

Thanks. I did some more searches and found a thread with almost the same setup.
2.7L to 3.0L Engine Conversion / Swap

I was planning on using my '77 exhaust system which from what I understand will be a backdated system" for the '81 Sc engine.

Seems like I need the lambda setup/computer and even a 6 pin CDI to get the swap completed, but does that mean I have to put a later exhaust system/cat with a lambda in the car as well?

Henry Schmidt · Henry Schmidt's Garage

You can eliminate the lambda control unit.
Remove the frequency valve and plug the holes.
Next replace the warmup regulator with the unit from your 77 and install the early exhaust.
Simple and reliable.

teveo · teveo's Garage

Thanks Henry, just what I need to hear.

I checked the bentley manual and from what I can find I will be removing the following components then:

- additional 15% throttle position switch
- frequency valve
- 35 degree temp switch in the crankcase vent (will stay if i dont find a suitable plug)
- 15 degree temp switch in the right timing chain cover (will stay if i dont find a suitable plug)
- the wiring loom with connector to the lambda system
- Warm Up Regulator being swapped with the 2.7 WUR

Based on this the only problem I see right now is the throttle position switch is routed in the same wiring loom/connector that I am taking off. I have to reroute it?

Perhaps the old 2.7 harness will fit to the 3 liter engine? If so I could always swap harness.

Flat6pac · 03-19-2009, 02:30 PM

Removing all the Llambda equipment means the Lambda harness will go away. The control harness is basically the same between 77 and 81, X the tach wire

Bruce

teveo · teveo's Garage

Quote:

Originally Posted by Flat6pac

Removing all the Llambda equipment means the Lambda harness will go away. The control harness is basically the same between 77 and 81, X the tach wire
Bruce

Thanks, you mean I get rid of the throttle switch as well? ( #20 in the pic borrowed from rennlist)

I dont remember perfectly.. but I thought that one was needed. I have it in my 74 cis carrera I think, maybe not? I will check tomorrow.

Flat6pac · 03-19-2009, 05:21 PM

The throttle switch on the74/75 operated differently, there was adjustment for somrthing, I dont remember what but I remember working on it. If its a concern, get a TB from a78/79.

teveo · teveo's Garage

Will try to install the engine in the weekend, all seem to be under control now. The throttle switch is non existing in my 77's CIS, so all the lambda stuff taken off now.

Seems like I have to install the oil return/inlet tube from my 77 engine, it is routed in the rear ("under the flywheel") whereas the 81 is routed in the front (under the fan pulley). I will borrow the 6 pin CDI from my 78 SC and hopefully the car is running early next week.

Henry Schmidt · Henry Schmidt's Garage

Don't forget to replace the warm up regulator.
Take the one off the 2.7 and put it on the 3.0.

You may also find that the 2.7 fuel distributor will also improve performance.
Good luck

teveo · teveo's Garage

Car runs great, thanks to everyone that left advice. I only have the tach connection to do,... test run with a frozen lake in the background..

KR8 · KR8's Garage

Hey Teveo,

I'm changing out a 76s engine 2.7 to a 83SC 3.0 about the same thing you just got done with. Reading through most the the threads on PP I thought I had to keep the Lambda system in. If I'm reading this right - I don't need to?

I will be removing the following components then:

- additional 15% throttle position switch
- frequency valve
- 35 degree temp switch in the crankcase vent (will stay if i dont find a suitable plug)
- 15 degree temp switch in the right timing chain cover (will stay if i dont find a suitable plug)
- the wiring loom with connector to the lambda system
- Warm Up Regulator being swapped with the 2.7 WUR

Based on this the only problem I see right now is the throttle position switch is routed in the same wiring loom/connector that I am taking off. I have to reroute it?

Perhaps the old 2.7 harness will fit to the 3 liter engine? If so I could always swap harness.

Then I'm off and running is that correct?

teveo · teveo's Garage

Yes, works like a breeze.

The lambda harness and its sensors goes off. The only part to modify is the fuel tube/hose around the frequency valve. You can plug the holes in the fuel distributor and use your 2.7's fuels hose if you like ..

Ricks911s · 03-30-2009, 06:11 PM

teveo, great post. very informative.

i'm doing a 2.7 to 3.0 swap as well. i kept the brain though for a couple reasons.

(1) wanted to make sure the engine smogged, and
(2) because I thought the engine should be run as it was designed to

The smog stuff is a PITA. This was the main reason I set up my car the way I did (81 engine w/brain in a 1976 chassis). I hope I didn't do this for nothing . . . but would appreciate your thoughts on how your setup would impact your smog results.

I think (2) is a matter of philosophy . . . and something i would probably change my mind if I understood the implications more.

Thanks.

Walt Fricke · 03-30-2009, 08:19 PM

If you want to run the '74 style exhaust, and also want the Lambda system, just drill a hole and weld in an oxygen sensor bung Put it just to the rear of the collector. Better yet, purchase SSIs with a bung already installed.

One or two wires in the 14 pin connector are in different positions in a '77 than they are in an SC's loom. Once you trace things out and figure what is what, it is not hard to disassemble one side of the plug (female, if memory serves) and move things around so they all line up again.

When I put an '82 in my '77 I was told I had to purchase a new tach, as the signal from the reluctor control and its associated CD box was not compatible with a tach made to run from the pulses sent by points opening and closing. So I did. I have since wondered if this was really necessary, but I didn't mess around trying it with the old tach. I still have that, so maybe I should just for grins. MSD makes (or made) a tach signal conditioner, and maybe that would have done the trick also.

Walt Fricke

T77911S · 03-31-2009, 04:28 AM

henry,
why do you say the 2.7 FD may be better? i was planning on putting my complete 2.7 CIS on my 3.0. i like the simplicity of the 2.7's system better, others have siad not to. .
until i puit the 3.0 in, i put the larger TB from the 3.0 on my 2.7, very nice improvment. i am surprised i have not heard of others doing this.

Walt Fricke · 03-31-2009, 05:18 PM

I'm interested in the rationale for the 2.7 FD also. But the 2.7 FD will bolt right up on top of the rest of the assembly, so it can stand alone, so to speak, on the 3.0 stuff, particularly including the throttle body.

But is the 2.7 flapper valve the same as the 3.0? Or do you want to use the whole 3.0 casting on that side of things, and just swap out the fuel distributor?

Henry Schmidt · Henry Schmidt's Garage

The late 3.0 fuel system was designed to be a lean running system.
The 2.7 was a rich running system that used thermal reactors and air injection to remove the extra / unburned hydrocarbons.
It is my experience that the 2.7 fuel distributor supplies more fuel than the late 3.0 fuel distributor.
More fuel allows for more power potential.
The euro 2.7 FD is a very nice piece for improved power.

T77911S · 04-01-2009, 06:41 AM

i love ya henry! several have tried to talk me out of the 2.7 CIS on my 3.0. i will and have mixed parts already. i have 2 complete systems and plan on the best from the 2 on the 3.0.
the only thing from the 3.0 i was going to use was the AFM, it is in better shape than mine. now that i think about it, is the shape of the "bowl" or venturi different on the 2. i have already put the 3.0 TB on my 2.7 for a very nice little improvement. some have even said the TB would not work well on the 2.7, but i have had no problems.

Henry Schmidt · Henry Schmidt's Garage

Quote:

Originally Posted by T77911S

i love ya henry! several have tried to talk me out of the 2.7 CIS on my 3.0. i will and have mixed parts already. i have 2 complete systems and plan on the best from the 2 on the 3.0.
the only thing from the 3.0 i was going to use was the AFM, it is in better shape than mine. now that i think about it, is the shape of the "bowl" or venturi different on the 2. i have already put the 3.0 TB on my 2.7 for a very nice little improvement. some have even said the TB would not work well on the 2.7, but i have had no problems.

I would not use the entire 2.7 intake unless you are running a small port 3.0.
Other wise go for it.