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wiring for 325i conversion in a 320
Posted: Sat Aug 13, 2011 8:22 pm
by retro-bmw
I have got my very early 320 ready for my 2.7 donk to drop in. I have everything sorted apart from the engine wiring plug.
What wires do I have to mess around with?
I have read somewhere that its 6 wires which go to the fuse box?
The engine which is going in is a facelift 2.7. Car is originaly a 1976 320 auto but is being converted to a manual using a 323i box etc
any help would be appreciated asap
Pictures/diagrams are more than welcome

Re: wiring for 325i conversion in a 320
Posted: Tue Aug 16, 2011 10:01 pm
by murran
west midlands? where abouts. if your within 50 miles i'll come and help you out for fuel money and beer.
and i'll come in mine! if i get my diagrams off drjim before hand i'll bring them too.
basically the big round terminal block on the e30 loom (c101)... theres 6/7 wires that need contecting to the e21 engine loom that plugs in the fuse box. theres also a perm live ring terminal into the e30 loom and an earth ring terminal.
Re: wiring for 325i conversion in a 320
Posted: Wed Aug 17, 2011 2:54 pm
by DrGonzoPOW
Just give him your pictures mate, there easy enough to follow. I managed it and im retarded
Re: wiring for 325i conversion in a 320
Posted: Wed Aug 17, 2011 11:54 pm
by murran
takes ages finding the right ones on my photobucket acc tho.....
there in my build thread and on gonzos build thread too. seek and yee shall find!
Re: wiring for 325i conversion in a 320
Posted: Fri Aug 19, 2011 1:26 pm
by retro-bmw
murran wrote:takes ages finding the right ones on my photobucket acc tho.....
there in my build thread and on gonzos build thread too. seek and yee shall find!
Thanks for the offer murran Got a bit delayed and ended up having the engine bay painted as it would have been rude not to when the rest of the car is going to be painted very soon. I will be hopefully be getting the engine in over the weekend but will be in out all day. Will have to find your build thread for this diagram

Re: wiring for 325i conversion in a 320
Posted: Fri Aug 19, 2011 11:20 pm
by murran
ok ive not really got much better to do tonight!
this....

needs wiring to here....

like this.... in the bottom right of the picture you can see ive mounted the c101 plug to the bracket where the old ignition modual (tci unit) used to be.

better pic.....
from the e21 engine loom plug to the c101 round plug on the motronic loom.
- ing. feed to the coil - green/violet to solid green, pin 7
- starter solenoid - big black to black/yellow, pin 18
- rev counter - smaller black (different pin to starter wire) to solid black, pin 9
- alternator exc. - solid blue to solid blue, pin 1
- oil light switch - brown/green to black/brown, pin 5
- water temp. - brown/white to brown/pink, pin 4
- fuel pump is simply earthed and fed switched live via the violet/red, pin 13 (id suggest putting an in line fuse in this just as it comes out of the c101 connector). run it into the fuse box and mount the fuel pump fuse somewhere like this...... with a trusty gluegun!
then run this wire back to the fuel pump live.
oh also in the pic above you can see i chopped up the holder for the three motronic relays and gluegunned them to the side of the fusebox.
the rest of the wires separate from the c101 are black sheethed wires grouped together with ring terminals on. brown/violet and solid brown both need earthing.
and 4 reds same deal need perm live.
i fashioned an under bonnet live pole out of a rubber mounting with m8 studs on either side.

live from the battery comes up to the pole then live to starter/alternator and lives to motronic loom come off it.
you also need to move the coil to the o/s wing and lengthen the wires on the motronic loom to reach it.
good place for it....

strip in to the remains of the e21 loom to pinch the coil wires.
youll need to fit the e21 dash temp sender in the e30 housing swap it with the brown one on the housing and convert the terminal.
can you add anymore tips gonzo??
Re: wiring for 325i conversion in a 320
Posted: Fri Aug 19, 2011 11:28 pm
by DrGonzoPOW
My tip would be to follow your wiring but do what varden did and use connector blocks before soldering everything up. I got some cheapy ones from Asda

Re: wiring for 325i conversion in a 320
Posted: Fri Aug 19, 2011 11:41 pm
by murran
^^^^ this.
oh you also need to hole saw the hole in the baulkhead somewhere on the passengers side to pass the loom thru then mount the ecu above the glove box or indeed ..... in it!

or do what i eventually did and take the glove box out and throw it away (never used the damn thing anyway) then mounted it the glove box hinge mounts.
Re: wiring for 325i conversion in a 320
Posted: Fri Aug 19, 2011 11:47 pm
by drjim
I drilled the hole for the loom below the glovebox so it comes through the vertical part of the bulkhead. Absolute bastard to secure it, I ended up making a metal ring which I bolted over the rubber grommet to hold it in place.
Also if you are wiring to the engine side of the C101 not the body side as in Murrans thread, there are two green wires you need to connect together, one of them goes to pin 27 and tells your ECU to switch on. Read my Baur rebuildathon thread to see how I discovered this!
Re: wiring for 325i conversion in a 320
Posted: Sat Aug 20, 2011 7:15 pm
by retro-bmw
Thanks for all the input guys
Got the engine all in today but did'nt go as smoothly as I wanted
The 323i gearbox is mega tight in the tunnel it is cathcing in quite a few places and is giving grief.
Any idea's why
Its a very early 320i auto which the engine is going in.
I have used a 323i subframe, wishbones, antiroll bar, 323i metal engine mounts, 323i rubber engine mounts.
Is something missing? Or am I going to have to give the tunnel some Hammer Action
Will upload some pictures later here and in the gallery section
Re: wiring for 325i conversion in a 320
Posted: Sat Aug 20, 2011 8:44 pm
by retro-bmw
A few crappy pictures
More pictures in the gallery section are being uploaded
Re: wiring for 325i conversion in a 320
Posted: Sat Aug 20, 2011 9:52 pm
by drjim
Tight fit there, I suspect the early cars had a smaller transmission tunnel as they were all 4 pots.
Important thing - Presumably your gearbox is like mine with the reverse switch at the top just behind the bellhousing, if so connect some wires to your reverse switch before you bolt it all in place, and check it works. Absolute barsteward to do with everything bolted together even with the car comfortably supported on a 2 poster. I would also get a holesaw and make a hole in the tunnel above it in case you need to change it in the future.
Re: wiring for 325i conversion in a 320
Posted: Sat Aug 20, 2011 10:30 pm
by retro-bmw
drjim wrote:Tight fit there, I suspect the early cars had a smaller transmission tunnel as they were all 4 pots.
Important thing - Presumably your gearbox is like mine with the reverse switch at the top just behind the bellhousing, if so connect some wires to your reverse switch before you bolt it all in place, and check it works. Absolute barsteward to do with everything bolted together even with the car comfortably supported on a 2 poster. I would also get a holesaw and make a hole in the tunnel above it in case you need to change it in the future.
That was my thoughts reagarding the tunnel Looks like im going to have to pannel beat the area a bit Its only a inch each side. Gutted wanted it all connected up today underneath.
Will keep the reverse wire in mind before I put it all together

Re: wiring for 325i conversion in a 320
Posted: Mon Aug 22, 2011 8:05 pm
by retro-bmw
Right bit of an update got all the running gear in and secured, Prop,323i tank with 325i pump, gearbox all mounted up.
I have got all the wiring through including the battery cable etc.
Fuel pump is wired up and works fine with the ignition.
The fun part:
I have temporarily connected the wires from the e21 loom to the e30 loom via block connectors as sujested following the diagrams but the statrter is not turning over with the ignition.
The E21 black wire is connected to the E30 black/yellow but it does not seem to have any live coming through.
I have traced the Ignition wire back to the Ignition point and it is the same story there no live to the black wire?
Any suggestions of what it can be?
Re: wiring for 325i conversion in a 320
Posted: Mon Aug 22, 2011 9:03 pm
by drjim
The other thing I discovered was that in an auto there is a start inhibit relay under the dash next to the wash/wipe controller. You need to pull it out and jumper two of the terminals - can't remember which and my car is now reassembled so I'm not able to check easily. 5 minutes with a multimeter some crimps and a bit of wire will get you going.
Jim