I have a 89 TBI 305 camaro and I want to install a 730 or 749 ecm. I know that a 749-730 swap just takes some repinning. what would I have to do. I think My ecm is a 8746

 

Yes, the '89 TBI uses a '8746 ECM. Are you staying with the TBI or going port? If going port then you will need the 8 injector connectors and possibly change the IAC & TPS connectors. As for the ECM side of the harness you'll need to get another connector housing. The '8746 is a 2 connector ECM while the '749/'730 is a 3 connector ECM.

Then it is just a matter of moving the connector pins around until they are in the proper locations. Both the TBI & '730 & '749 wiring info is around.

If going to a port system it may just be better to get a SD port harness. A study of the two systems wiring differences will help to decide which is the better path. It also depends upon which port system, TPI has the IAC & TPS way up front, so those wires would need to be extended. If a single plane port, then they are in the correct location.

RBob.

 

Hi RBob,


The motor will be a zz430 and I have not yet decided how to feed it.
I will go with one of the three
1. ramjet
2.4 barrel Tbi
3. Add injectors to a manifold, for port injection.

I just bought a 89 that has a 305 TBI. I also have a 89 camaro with the zz430 already in . I would like to put the 749 ecm in the car that has the TBI. Then I would like to buy the promintator and learn using the 305. In A couple of months I will swap out the motor and use one of the three methods above to run the motor.
For now I need to run a 305 TBI with a 749 ecm

 

Ahh, OK. Get the wiring diagram for the turbo Sunbird (diy-efi site) along with the TBI wiring. Then use it to see which wires need to be moved to which connector. You will also require another connector shell.

RBob.

 

Thanks for the reference , RBob

Comparing the 749 and 8746, almost every wire will need to be moved. Would it be better to make an adapter harness to adapt the existing harness to the 749? If so where could I find the connector for the 8746 that will plug into the wire harness? If I repin, can you suggest some reading that will show me how to do this?


After comparing the wirring schematics Im not as scared to do this swap, Even though almost all wires need to be moved, many of the wires are the same colors

 

An adaptor harness/board is a nice way to go. This would allow you to run either ECM. The downside is that it is time-consuming to put together. And getting the parts. I know of people gutting an ECM for that side of the connectors.

If doing the re-pinning then a shell can be had at a junk yard. I look for vehicles that the engine has been removed from. Typically they cut the harness out with it. This leaves the ECM ends intact with 2 to 3 foot wires attached. Can get them cheap.

There is a trick to getting the pins out of the connector. I've taken some 1/16" rod/wire and flattened/filed the end. This allows the catch on the pin to be pushed aside and the pin comes right out of the connector.

May need to forcefully pull a pin out to see the catch and how to release it.

RBob.

 

looks like the repin is the way to go for me. I cant see a reason to run the 8746 ecm again. It looked like it wouldent be that bad of a swap comparing the schematics. I know I will have a couple of questions after I have time to study them out more

 

The adapter isn't too hard to do.
Well, after you do it a few times, it gets easier <g>

Here's mine.