2.7L to 3.0L Engine Conversion / Swap

[Ricks911s]

This is absolutely perfect. Thanks.

[kristan]

From the wiring diagram I get that the black/violet cable from your speedo
is connected to the Electronic ignition unit.

From there - and now I am guessing - it goes through the 14pin connector
to the front.

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_Part1-2.jpg

Christian

Update: I can confirm that it goes through the 14pin connector at terminal 12!
Late Update: In a SC, probably not in your car :-(

[don gilbert]

rick, on the tach, find the b/p wire in the main harness (in engine comp) coming from the fire wall. its there, but not in the engine harness. others might chime in and say this is wrong, but ive always hooked it up to the hot side of the coil. mine and others ive done this way worked fine with thousands of miles with no probs.

[Ricks911s]

Is this what you mean Don? (see this other thread)

Tach Wiring

[boyt911sc]

Rick,

The 14-pin connectors for '76 & '77 are the same as those in the SC's. The black/violet wire from the tach goes to pin #12. Your wire harness (engine side) should have the black/violet in #12 too.

The two-port fuel accumulator will work well for both SC's and '76-'77 cars. No need to change unless you want to spend and buy a three-port FA. The 3.0 liter motor you bought will have a return line for the fuel accumulator. Plug it for 2-port FA or use it for a 3-port FA.

If you are using the 6-pin CDI, it will be a simple plug in work. Not familiar with the MSD 6AL ignition set-up. Keep us posted.

Tony

[boyt911sc]

Originally Posted by don gilbert

rick, on the tach, find the b/p wire in the main harness (in engine comp) coming from the fire wall. its there, but not in the engine harness. others might chime in and say this is wrong, but ive always hooked it up to the hot side of the coil. mine and others ive done this way worked fine with thousands of miles with no probs.

Don,

Connecting black/purple wire from the tach directly to the hot wire of the coil will work for '76 & '77 cars because they have points (distributor) and use 3-pin CDI. On the other hand, the SC's are using 6-pin CDI and wired differently. The wiring diagrams for the '76 & '77 and the SC's are completely different for the ignition system.

I'm interested to know if you have done this on an SC engine with 6-pin CDI. As you said it, this was done by others too and would like to learn something new. BTW, the wire in pin #12 (engine side) should be black/purple and will plug in directly.

Tony

[HarryD]

Originally Posted by Ricks911s

Some progress to report.

... Purchase these parts:
- Lithium Grease (for all electrical connections)
... -

I would not use Lithium grease for electrical connectors. Get a tube of DIELECTRIC GREASE which is made specifically for this purpose. It is thicker and will not tend to run.

[Ricks911s]

I just received the rest of the parts to finish up the clutch and think I know enough about the tach wiring to try a couple things and see what works best. I still hope to hear from Don on where he wired the harness to the front fuse panel.

Thanks HarryD, I did mean dielectric grease, not lithium grease. So thanks for giving me the added reminder.

I ended up drilling the hold for the ECU a little low (advice for further people drilling this hole). To make sure you don't do this, just don't drill the hole in the bottom right hand corner (passenger side). Go a little higher, at least halfway or more up. (sorry about the bad pics)



As a result I had to wire the harness over the transmission.



I'm going to take a closer look to see if I can simply make the hole a little bigger to negotiate a more direct route.

Thursday I have a day off and I am going to do several things including some of the "common oil leaks" Wayne suggests in his book. I'll probably mount the ECU unit under the passenger seat also.

Re-install clutch, plug in related wires, new fuel filter, re-mount engine, plug in all the lines (oil/fuel), new oil/gas and turn the key (hopefully this next Monday).

[Ricks911s]

I made some progress with mating the engine and getting it to a position where it could be installed. The engine doesn't want to go in! (engine install)

Now I'm to the point where I need to tie off some lose ends in order to finish the conversion/swap. And, as such, I now need help from the electrical gods.

Felixcontour helped out by posting a picture here '81 CIS ECU wiring question of the '81 wiring deliema. Tony (Boyt911sc) helped out by answering the questions directly but I'm in a situation where I'm trying to figure out what fuse ('76 chassis) goes to what wire ('81 engine harness/dme).

As I understand it the three wires in question on an 81sc -- The Diagnostic connection (red) and the 2 wires (red & red/white) that come directly from the ECU.

It appears the Test connection/diagnostic wire goes to rear fuse #22 (25a). It also appears the ECU red wire goes to Fuse 18 (5a) and ECU red/white goes to Fuse 30 (Fuel pump relay). I can make sense of where the red/white wire form the ECU goes but not the other two (diagnostic red wire and ECU red wire).

The question becomes this: what are the corresponding fuses from an '81 to a '76 for the diagnostic port Fuse 22 (25a) and for the ECU red wire Fuse 18 (5a)?

[Ricks911s]

Okay, well it's time for an update. Made a lot of progress but have
started several additional threads because there were some specific
questions I had that wern't answered here.

With the help of Tony, (ECU wiring) we figured out the proper wiring to help my '76
evolve into something with a "brain" (an ECU/DME harness from the
'81). Thanks to his guidance, I wired the red/white line from the ECU
went to terminal 30 on the FP relay, the red line form the ECU went to
my fuel pump fuse (#18). The rear diagnostic line I wired to the rear
middle fuse and grounded to the chassis. I hate wiring or electrical
stuff . . . so Tony's help was very very appreciated. Hopefully the
vampire clipping will work until I have more time re-do my fuse box .
. . which I hope to complete somewhere down the line.

Putting the engine in was a PITA. Based on the help of others, I
think this was due to inproperly disconnecting the shift coupler
(stupid me . . . since that's one of the easier parts of the engine
install). Anyway, I pulled the trans out, replaced the shift coupler
seal and the main driveshaft seal (thanks to the suggestions of others
and only minimal pain to my wallet) and slapped the two in. Well,
maybe not slapped . . . since it took hours and hours or figuring out
the right way to do it with the engine on an ATV jack and the trans
on. but anyway, it's in.

my fuel pump (FP) had been leaking before due to using an aftermarket
Walbro pump (since I couldn't afford the original 76 pump from PP).
The banjo fuel line from the pump to the rear pressing down on one end of the fuel pump, putting pressure on the fitting . . . thus creating a leak. After cutting the line shorter, refitting the banjo, and connecting everything up . . . it now works
without leaking. Whew . . . thank god.

There are several remaining issues, the biggest of which is the oil
line from the crossover oil pipe on the '81 connecting to my '76 oil
tank (see post crossover tube help needed! 2.7 to 3.0). It's hard to explain in words . . but the crossover pipe in a
'76 comes under closer to the front of the car. The '81 crossover oil
pipe runs closer to the back of the car. The upshot is that the line
from the oil tank just can't be adapted without pinching the line. So
I need to find the appropriate line for the intermediary solution . .
. or find the rest of the lines for front cooling (i have all lines
except those that goes from the engine/tank to thermostat).

The second issue is the return fuel line. They're different sizes on
the 76 chassis and 81 engine side. I've a temporary solution . . .
but will have to figure something more permanent or long term.

There's one plug that I can't figure out. But I don't think it's
mission critical. It has a different plug than all the others.

I replaced the breather hose on the '81 with the one from the '76 since
the breather hose on the '81 was cracked. When putting in the engine,
the hose was pinched between the engine and the chassis. I got it
loose, but now it's not properly routed and it doesn't exactly reach
to the oil tank. I'll have to wiggle that thing around until I get
enough slack.

I still need to do the tach wiring, but plan to do this soon. I'm
simply going to extend the purple/black line in the rear of the
engine. If that doesn't work, then I'll run the wire all the way
through (from tach to engine compartment and to pin #12 on the 14
pin).

Aside from all this, I'll need to pay more attention to the inside.
But that's not critical to the swap / conversion. So I'll update
after the engine starts and I confirm everything works.

[Ricks911s]

A few years have passed but I'm back to where I ended up. I pulled out the 3.0 and did a top end rebuild after a couple of years and need to hook back up the electrical wires in the back.

I forgot to take pictures of where I had connected all of the wires and I'm trying to work with the mechanic who is putting back in the engine (in Emeryville) to get it all going. Shig (my mechanic) has been doing a great job, but he and I are both ready to be done.

There are a few wires that we need to sort out. For those of you that haven't read the entire thread, I am updating my 1976 chassis with a 1981 3.0L engine.

There are two groups of wires. (see photo)

The wires with the red box around them I've isolated first. The black/violet wire goes to the tach (pin 12 on the 14 pin connector). I think you can jump the connection over, as I recall (see photo for pin top second from the left).



The other two red wires in the red box, I'm unsure about. My memory says they go to the other wire that is in the first picture above (left of the red box...the wire with the masking tape around it). BUT, I also remember that I jumped from the top fuse between the red box and the other wire. I cannot remember where!!

If I look at the 81 ECU diagram (see below), I WANT to say that the line from the ECU brain that I installed under the passenger seat jumped into the wire to the right of the top fuse. I am having a hard time remembering the outcome of this post: '81 CIS ECU wiring question



Can anyone help? Last step until my mechanic in Emeryville and I celebrate this very very long project.

Thanks....

[jeffs9146]

When I converted my 75 914 to an 83sc 3.0L I found it easier to understand the plug from the chassis and knowing which wires you will be able to use and which ones you wont! I was able to switch the pins on the motor plug to match the ones that were a direct conversion on the chassis plug. The ones that are left from the motor plug that didn't match anything from the chassis were pulled out and run externaly or the unused pins from the chassis plug used and the chassis end connected to the proper item...ie:Oil Pressure sender that the 914 didn't have!

I don't know if any of this is helpful but when I was done the motor fired on the first click for me so it worked! As for the brain power I just connected it to an ign source that was hot after the motor started under the dash and grounded it under the seat!

[timmy2]

Brown with black stripes wire that is taped is the wire for your fuel safety switch. It needs to be jumpered to the white plug on the engine harness brown/red wire. I don't know what else Tony had you do so i cant advise.

I would have had you wire up the tach signal to the male 14 pin connector on the fuse panel and leave the engine harness alone.... Along with 2 other chassis harness wiring changes to make it completely plug and play.
There are only really 3 wiring changes that need to be made to mod the '76 &'77 cars to accept the '78 to '83 harnesses for plug and play.

Move the purple tach wire to the 14 pin male connector terminal 12, move the brown/black wire to the white T connector and one other that I can't remember off the top of my head....

Edit, brain kicked in, it was moving switched power to the white T connector as well. (Both changes to the chassis/male side of T connector)
Doing it this way allows for the 6 pin CDI to work properly and have a clean plug and play installation.
No messy jumpers or wires hanging around.

[Ricks911s]

Thanks Timmy/Jeffs.

The wiring is all sorted in the front fuse box and the ECU is installed and everything worked before. I'm trying to remember how I did it in the back.

Jeffs, which wire are you referring to as the white T connector? Is there anyway you can help me think through what the third connection is?

I'm so close!

[timmy2]

I believe you can take switched power from the top fuse of the 3 fuses on the rear panel if unused.
See edit to my earlier post.

[jeffs9146]

Timmy was the one talking about the white T!

Are you still working on the main engine harness or the FI harness? The FI harness is just constant power, Switched power ground, 02 sensor and temp sensor (depending on year)!

[Ricks911s]

Thanks Jeff/Timmy...

So, looking at the ECU wiring harness (yes, I've installed this under passenger seat and wired to front), I am trying to determine the connection points in the back. After you wire it through the firewall to the back there (1) pin connector -- this is easy mate up, (2) the O2 sensor -- hangs off, (3) ground, (4) and loose wire. Everything except for 4 makes sense. I think, per Timmy I jump this into the right side (front of car) between two top fuses (rear engine compartment drivers side).

Timmy -- thank you for the update. I'm just not grasping the edit "it was moving switched power to the white T connector as well. (Both changes to the chassis/male side of T connector) Doing it this way allows for the 6 pin CDI to work properly and have a clean plug and play installation. No messy jumpers or wires hanging around."

I jumped wires before...and I'm trying remember even that.

[timmy2]

Do you have any pictures from your original install?
I was reading your earlier posts and they jump all over so I'm not sure what you did originally.
Pictures of your current engine harnesses would help as well.
This is a prime example of why we need to document our mods, laminate them and keep them somewhere safe!

The edit was referring to the one other change I couldn't remember when I first posted.
I could direct you in how to do the wiring changes starting from scratch easier than trying to guess what you have done before.
I'll have to look at my schematics at home tonight before saying anything else.

[jeffs9146]

I don't have the two wires hooked to anything! The red one and the brown one with the small ground loop are just wire tied to the 02 sensor wire! When I did my conversion I was told by a Bosch Injection Specialist that they are not needed! He did tell me what they are for but I can remember!

[timmy2]

Originally Posted by jeffs9146

I don't have the two wires hooked to anything! The red one and the brown one with the small ground loop are just wire tied to the 02 sensor wire! When I did my conversion I was told by a Bosch Injection Specialist that they are not needed! He did tell me what they are for but I can remember!

Are you talking about the injector harness?