The procedure seems pretty straightforward, but I got to thinking about the distributor, and how it doesn't have a tach-drive on it (which I need in the other car), so I was wondering, if I were to tell the computer to ignore the input/output for the distributor, could it cause other problems later?

Of course I'd also need to disable the knock sensor...

 

You don't need to disable the knock sensor, just unscrew the block drain and screw it in.

 

Mechanical tach drive distributor, haven't seen one of those in a long time.

You can have an EFI setup without engine timing control. However, you still need to provide a DRP to the ECM. The ECM requires distributor input to calculate the RPM, handle the crank routines properly, and to know when to fire the injectors. From points: filter it, and level convert to 5V maximum (0-5V Sq wave). Then feed it to the ECM.

RBob.

 

What I do is just install a magnetic pickup and reluctor from something like a Ford duraspark or a Mopar electronic distributor into mine.
Then you can take full advantage of the timing and fuel control.

The other option is to add a timing wheel to the crank and go DIS.

 

Why not just install a electronic disty and wire it correctly?? That way you will have infinite adjustability of your timing curve and wont have to worry about the details??

 

i have to ask, other than having it, is there a reason you have a mechanical tach?

 

It's a C3 'vette, so I want the tach to look stock, the electronic ones don't look right.

I'm running HEI, so it has a tach output plug on it. I think that's a 5v square wave, though I'm not sure. The distributor is an aftermarket unit that looks a LOT like an ACCEL, but it doesn't actually have branded parts inside. I'll bet it's a Chinese copy, but it's worked flawlessly so far.

In any case, if that's all that needs doing, I think running the TBI from my old FB won't be such a problem after all. Thanks!

 

If you are running HEI then you can swap the 4 pin module inside to the 7 pin module for timing control and keep the rest the same.

 

Really?

Not difficult, is it?
Anyone have a tutorial?

 

I'm a little confused on your distr.
You said it's a C3 vette with a 350 running a large coil in cap, HEI distr that is equipped with a cable tach drive output, but also has the tach output plug on the cap.

Is all this correct?

I'll see if i have a large cap distr in the shop but I think all mine are the later small cap distr's.

 

 

Makes sense now.

You can lock out the mechanical advance with either a tack weld or a screw.
Then leave the vacuum hose disconnected.

Then you can remove the 4 pin module and install a 7 pin module.
The pick up wires will go to the P and N terminals and the rest will wire up as per the ECM wiring diagrams.
I didn't have a large cap HEI. I was hoping to document the conversion to keep on file. Sorry.
Did a google but didn't see a write up readily available.
I'm sure if you hit the junkyard you could find a large cap HEI with the 7 pin module and connectors you would need to make a clean install.

 

I'm going to assume that any GM coil-in-cap vehicle between 81 and 90 has one, is this correct?