M20 Engine Swap question from a 323 to 320

[fgin]

Hi guys


I hope you can answer this quiet easily. I have searched but im not seeing a definitive answer.


I have a S1 84' 323 manual coupe that has a fairly good running M20 engine and transmission.
There is some rust and panel damage in it which will cost a fair bit of effort to fix so not keen on going that path if I can avoid it.


however I found a S1 88' 320 convertible with no rust at all and everything intact cosmetically but has no engine + transmission (was originally manual too). Rest of the car is in great shape and worth restoring.


I am thinking of swapping the 323's M20 engine and the manual transmission into the 320 vert. I have access to a hoist, tools and some help. I was hoping this could be a quick fix.


From what I have figured out so far which has started to worry me is that,
- the 323 has the Jettronic Rectagle c101 plug
- the 320 has the Mototronic Round c101 plug


So my question is,
Based on the table here
http://www.e30zone.net/e30zonewiki/i...ine_Swap_-_M20


Can I make a harness like this but in reverse ?
https://www.flickr.com/photos/312317...n/photostream/


That is to fit the Rectangle engine harness to a Round body harness?


Please note that the 320 did not come with the engine or engine harness.


Any help will be much appreciated ?


Thanks a lot.

[superj]

I would imagine you could make the harness if you had the diagrams. I cannot open your link so I cannot check what that is

[nick325xit 5spd]

Ideally, you'd want to just convert to the late Motronic setup.

[fgin]

Ideally, you'd want to just convert to the late Motronic setup.

You mean modify the engine to have the toothed pully , crank sensor etc and use a motronic engine harness ?

[nick325xit 5spd]

You mean modify the engine to have the toothed pully , crank sensor etc and use a motronic engine harness ?

Yes.

But nothing would prevent you from converting the square plug to a round plug.

[fgin]

Am I overthinking this ? e.g. wont the motronic ECU in the 320 be expecting certain signals from the engine (such as the crank position) to enable ignition, fuel pump etc? the 323 engine wont have these sensors
or do i need to change the ECU and maybe the ecu harness in the 320 to the one off the 323 as well ?
At this stage my aim is to get the car running with least effort and cost.
Thanks for your help and advice

[nick325xit 5spd]

Am I overthinking this ? e.g. wont the motronic ECU in the 320 be expecting certain signals from the engine (such as the crank position) to enable ignition, fuel pump etc? the 323 engine wont have these sensors
or do i need to change the ECU and maybe the ecu harness in the 320 to the one off the 323 as well ?
At this stage my aim is to get the car running with least effort and cost.
Thanks for your help and advice

The ECU directly attaches to the engine harness. The only real difficulty is 1) getting the square plug connected to the round plug on the chassis (please don't cut the chassis harness), and 2) if the emissions inspectors are really serious, you may have difficulties getting an older engine with old engine management smogged.

Edit: To be 100% clear, you need to swap basically everything that attached to the engine to the 320.

[fgin]

The ECU directly attaches to the engine harness. The only real difficulty is 1) getting the square plug connected to the round plug on the chassis (please don't cut the chassis harness), and 2) if the emissions inspectors are really serious, you may have difficulties getting an older engine with old engine management smogged.

Edit: To be 100% clear, you need to swap basically everything that attached to the engine to the 320.

1) I dont intend to cut anything but make a harness like this but in reverse. Im guessing your advice not to cut is based on being a purist like me ? If not please explain.
https://www.flickr.com/photos/312317...n/photostream/

Im pretty confident in finding the make/female connectors and making this harness. So no problems there.

2) I doubt this will be an issue here in Australia

If you think 1) is my only challenge then is it correct to assume the following is what I need to do to get this car running?

- I take the 323's M20 engine+transmission, engine harness (with rectangle c101) and the ECU from the 323 and move it to the 320.
- build the conversion harness so I can connect the rectangle c101 engine harness to the round c101 on the body of the 320.

This should get me going?

I know Im being a pain but thanks for the patience.

[nick325xit 5spd]

1) I dont intend to cut anything but make a harness like this but in reverse. Im guessing your advice not to cut is based on being a purist like me ? If not please explain.
https://www.flickr.com/photos/312317...n/photostream/

Im pretty confident in finding the make/female connectors and making this harness. So no problems there.

2) I doubt this will be an issue here in Australia

If you think 1) is my only challenge then is it correct to assume the following is what I need to do to get this car running?

- I take the 323's M20 engine+transmission, engine harness (with rectangle c101) and the ECU from the 323 and move it to the 320.
- build the conversion harness so I can connect the rectangle c101 engine harness to the round c101 on the body of the 320.

This should get me going?

I know Im being a pain but thanks for the patience.

Yes. You should be able to find the pinouts pretty easily from a M5x swap guide.

While the engine is out, you should plan to do all the hoses, the manifold gasket, and the bitch tube o-rings. Note that you will probably need to use the late cooling system as I don't think that the 320 will have the mounts for an early style radiator. But you really should replace the radiator anyway.

[fgin]

Yes. You should be able to find the pinouts pretty easily from a M5x swap guide.

While the engine is out, you should plan to do all the hoses, the manifold gasket, and the bitch tube o-rings. Note that you will probably need to use the late cooling system as I don't think that the 320 will have the mounts for an early style radiator. But you really should replace the radiator anyway.

Pin outs are here so no probs with that.
http://www.e30zone.net/e30zonewiki/i...ine_Swap_-_M20

Yes, Im planning to do a good refresh on the engine before it goes back in.

Already did the oil pan gasket as I got the car with it cracked. So had to do to see the engine running. Im kind of sad to wreck the 323i as its a manual coupe with a straight body. Only rust I see is on the firewall near the battery tray all eaten away and the floor. Rest of the car seems solid and no rust at all. Interior was stripped but has all the bits to put it back together. Now that I found the convertible I am inclined to get that up and running instead. Maybe once the engine is out I can attempt the firewall fix. If all goes well M50/M52 or M54 it

Anyway the rest of the work I had planned for the engine was
1. New Oil and Filter - Already did with oil pan
2. New Fuel Filter - Already did prior to start
3. New Water pump - todo
4. Timing belt kit - todo (Wondering how hard it will be on the older engine. Saw a DIY on the toothed crank pully version on the m20 which is not the case for me. That looked like a lot of work)
5. New ancillary belts - todo
6. New hoses and intake boot - Engine revs high once I start and I think its because the intake boot is cracked. Where can I get all those bendy vacumm hoses from?
7. New transmission oil
8. Manifold gaskets
9. Which o-rings are you referring to ?

The 320 has the radiator so I might try to keep it if in good condition. Apart from mounting points, are the radiator hoses etc any different ?

Apart from the radiator Im thinking of replacing;
- Clutch and bearing (no noise at present and it seems to be working fine)

Will the 323's exhaust fit straight into the 320 convertible ?

I will take some pics of the 2 cars soon and upload here.