Electrical help please! (FB to SA engine swap woes)
 

So a while ago, I did a swap on my '79 from an '83. I didn't realize that the two had very different charging systems. Right now, I have the distributors switched but the alternator is not hooked up because the wiring harness is different. Is there any easy way to re-wire my '79, or will I pretty much have to switch out the entire harness? I would like to switch back to the '83 electronic distributor as well. Please someone help me out!

The alternator wiring is really simple, but I've never had a '79 so I don't know what the difference is exactly, does the '79 have an external voltage regulator?

The '83 alt just needs 3 wires, 1 bolts to the stud on the alt and goes to the + terminal on the battery. Then for the plug/connector it's a 12v+ wire switched by the ignition and a ground, not sure which is which without looking at the wiring diagram, the wire colors usually make it obvious, but make sure you don't get them wrong or the polarity will switch, the alt will send + out the ground...it might have diodes inside to prevent this, but I'm not sure. These wires should all be there on the '79 harness, might have different plugs and if it has an external voltage regulator that will need to be removed.

I'd have to look at the wiring diagrams for both dizzys to see what needs changed there, havn't messed with the older dizzys at all. I know they have different ignitors and points vs electronic, but I don't know how different the wiring is.

I can't remember which is which, but the '79 and '83 have opposite internal/external voltage regulators. The cars have different dizzys, alternators, and coils.

Because the wiring to the alternator stays with the engine during swap, the alternator still plugs in. The problem is that there is no wire for the positive out to the battery. If that's all I need to make the alternator charge the battery, I could just wire that myself. And if I must, I can keep the points dizzy. In that case, would I need to keep the '79 coils or switch to the '83?

The 1979 uses different ignitors for the dizzy. The easiest way would be to get the wiring harnes that goes from the coils to the dizzy. It has the ALT positive wire as part of it. I think any 1981 to 1985 one would work. Check out this picture in my profile. There is a harness that goes from the ALT and dizzy back to the coils and runs over the AC compressor. This is what you need.

https://www.rx7club.com/album.php?al...ictureid=41383

The 79 has a external regulator and the 83 has the internal regulator, so using the 79 alt wiring won't work with the the 83, The 79 alt has a positive out wire that connects near the main harness to a white and red wire which then goes to the fusible links. As for the distributor I would go with the 83 electronic dist, no points or condenser to worry about, but some wiring would need to be done and it needs the 83 coils.

The 79 used a points ignition with ballasts - - no ignitors at all. Plus, as noted, an external Vreg.

Considerable differences electrically. It would have been simpler to bring your 79 alt, dizzy & engine harness onto the 83 engine.

Using the 83 electricals will be more reliable, but you've got a number of wiring changes to make. Time to start comparing wiring diagrams.

Please post pictures of your current wiring from the coils to the dizzy. Did you use the dizzy from ther 79 or new engine?

Right now, the dizzy from the 79 is in the '83 engine.

Sorry, should have done this to begin with. I'm going to apologize for how dusty the compartment looks. I just had a lot of body work done and the ass-jockeys that did it did everything with the hood removed. So everything is embarrassingly dirty. You also will probably notice there is no rat's nest. Don't let that trip you up.

I just decided to make a video and take pictures. Hopefully between the two we can figure this out.

Here is the video:

http://youtu.be/HmncccpcOc8

And pictures:

https://i.imgur.com/VwXjW.jpg
https://i.imgur.com/Mr6Gi.jpg
https://i.imgur.com/BkTmd.jpg
https://i.imgur.com/QAngp.jpg
https://i.imgur.com/BmNw0.jpg
https://i.imgur.com/OyzGV.jpg
https://i.imgur.com/HibwP.jpg
https://i.imgur.com/Gqqsw.jpg

As you have it set up now the distributor wiring should be all good, if you want to use the 83 electronic distributor in the future it is a very easy swap with a few simple wiring changes. If I understood what you were saying you used the 79 alt with the 83 wiring harness, which I don't think will work because the 79 alt needs to be connected to the external voltage regulator, the 83 alt has an internal reg, but I could be wrong. The alt positive output wire is a thick 6-8 gauge wire that is ran to a connector near the main harness, so that little wire with the o-ring connector is not it, and I think your right in grounding it.

The bolt your pointing to in ther video is suppose to be connected to the main positive line. Grab the wiring diagram for the 79 from the link below. On page "A" it gives a schematic and also a picture of each plug. The connector is called A-09 in the wiring diagram and is colored black (b). The wiring diagram might help hunt the right wire down.

http://foxed.ca/index.php?page=rx7manual#firstgen

Looking at the pictures, the black wire that you connected to ground sure looks like a ground and not one that goes to the alt.