81 driveline into a 78 body :)

[ritter4242]

Hey guys,
So at long last I have a body for my 81 911!!
To refresh; I bought an 81 911 SC from a junk yard sight unseen, told it was fixable.. and it wasn't (don't worry she'll be made into a race car at some point) and the search for a body began. Well today I went out to Omaha to pick up a beauty that's been in storage since the 90's! (thank you chuckne!!) the interior is beautiful, and the exterior isn't perfect but hey there's the excuse to paint it!! ;D Anyway I was wondering if anyone had done this before (put an 81 into a 78) what I need to watch out for and if there were any tricks to it. I was considering taking the entire rear end off and putting it into the 78 so I don't have to disconnect the axles but I'm not sure that will work. if I did that I would take both the front and rear off and just switch them so the 81 will still roll. I'm really excited to get cranking on the 78 but I'll be heading back to school this weekend. Any ideas suggestion or sympathy? I'll hopefully be posting pictures of the cars soon!

[Dave Colangelo]

78 and 81 should both be SC's so there should be no difference in getting the driveline in there. The only change in the SC was the introduction of the Lambda loop system (I think in came in during the 1980 model year). Other than that all 911's from 78-84 should have a 915 and a 3.0L engine so I dont see any reason why it would not just slip in.

Regards
Dave

[ritter4242]

ok, I'm assuming the loop you speak of is the oil line running along the passenger side? the "hood" says carrera on the 78, had they just not started calling it the SC? just formalities here really I"m really excited to get this bad boy back on the road!

[Mr Project]

Ritter4242, I don't want to damp your enthusiasm, but I looked at that shell as well and it had been hit very hard earlier in life, with a number of panels up front not being straight, including around the smuggler's box, the HVAC ductwork, and the windsheild. Before you put a lot of work into the drivetrain, I think it would serve you well to get the tub measured and possibly straightened if necessary.

[Dave Colangelo]

The lambda loop system had something to do with the CIS injection system. Im not quite sure what it did or how it worked as my 78 does not have it. I know that the system involved some electronics of sorts (some of which were mounted under the seat I think). If the engine lid on the 78 sad Carrera that could mean a few things.

1) its a 75-77 Carrera that they were calling an SC incorrectly
2) its a 78-83 SC that some one at some put put a Carrera badge on
3) its an 84-89 Carrera that they thought was an SC

The Carrera name appeared on the cars from 75-77 and then from 78-83 the SC or Super Carrera name appeared. In 84 they went back to the Carrera name.

If its still there you may want to decode the vin and see when it was actually made.

Regards
Dave

[javadog]

The lambda system was the oxygen sensor and related components. There are a lot of detail differences between a '78 and the '80-and later SC. For your purposes, the engine will go in the car easily but if you want to run the O2 sensor (and I think you should) you'll need to install the O2 sensor control unit and related electrical bits under the seat in the passenger compartment and install the correct wiring harness to connect the two things. There are a few more little odds and ends to do it correctly but some of them aren't essential.

JR

[ritter4242]

Dave-
dammit... that's exactly what I DIDN'T want to hear.. /:
so how do I go about the vin check?

java-
do you know of any other members doing a write up on this? are there any diagrams? I'm going to just take out everything from the 81 that I need, put it into the 78 and have a running car. Then the plan is to take the 81 to a shop have her fixed now that I don't need to worry about having a good body and turn it into a race car.

Mr. Project-
the car is in excellent condition she's one heck of a find. there isn't any damage to the body or frame.

[javadog]

I don't know of any thread that specifically walks you through this. I'd get a set of factory manuals to get the wiring diagrams and I'd get a copy of the 1980 Service Training book that talks about the changes made for 1980. A copy of the '81 books might also be useful. None of this stuff is sitting on a shelf but it can be tracked down if you have patience.

JR

[DaddyGlenn]

Get the Bentley book and use it as a guide to drop the engine and transmission. (disconnecting the CV joints at the wheel end not transmission end) Do the reverse to install it in the other car. Assuming the electrical connections are the same with the exception of the Lambda circuit and the CV joints/axle are the same, it should be just that easy.

[Dave Colangelo]

This should do the trick

VIN decoder - Stuttcars.com

As for the lambda system, you have the motor form the 81 so it will have it. It depends on how far down you plan to strip the car. If you are going all the way to the chassis then I would just pull the electrical system form the 81 and put it in the 78 along with the engine. If you are leaving the electronics in you will have to either mod for the lambda system or back date the engine to run with out it (im not sure if this is possible). What ever you do make sure you install a pop off valve in the air box while you hare in there. I would also look around here for the list of "while its out" projects for your engine.

Another option of course is to alter the engine to run carbs. I have no idea how to do this or if it has any advantages (it most likely brings problems if any thing) but may be worth looking into.

Regards
Dave

[ritter4242]

java-
I plan on taking lots of time doing this, I have my 944 to finish and my friends I "bought" to fix up.. I'll probably get to work this summer or spring break

glenn-
I was planning on dropping the entire rear end, and switching the suspension out front and back on the 78 from the 81. First off it will save me one hell of a headache with the CV joints, had to take them apart on a 944.. ended up having to use a torch and a vise grip.. and I'd rather be running the 81's gear.. I feel it will be more.. "sporty"

dave-
Thanks I will look into the vin.. I guess the plan will be strip the old girl's down and see whats under the skirt I plan on running the 81's engine as is. I heard it run and man she sounds great! I'll probably end up dropping the engine and transmissions and just start swapping parts from the 81 into the 78 until I have everything I need over there ( I was planning on doing something similar with and 85/2 and an 84 944 ..but I'm going to just strip the 85's block down and rebuild it for the 84 but thats a different story :P I'm really looking forward to climbing into that car and being able to start it without ether /: on a side note what is this pop off valve you speak of? I really hope to have my girls out at a meet with you guys someday soon ;D

[ritter4242]

well I looked into the vin.. it IS a 78 and it IS a 911SC /: I guess she has a story somewhere

[redturbo911]

Yes it will fit it.

[Dave Colangelo]

Here is the pelican article for the install,

Pelican Technical Article: CIS Pop Off Valve Installation

The article says its for the 911S (2.7 motor) however the 911SC also had a CIS system on its 3.0 motor so the article still applies.

I have one on my SC and it saved me just the other day actually. Essential when there is a back fire in the intake it allows it to vent out as apposed to the air box blowing up. I have heard many stories of this happening and made sure my car had it when I bought it. If you use the car on a regular basis it is not much of a problem but when my 911 sits around, as it does while I am at school (I bring the 944 with me) it seems to be more susceptible to back fire when I go to start it after a long time sitting.

Regards
Dave

[ritter4242]

Dave,
the previous owner must have really loved her, it has the valve in it already! so there is one less thing that I have to do