Backfire and idle issues

[anothersteveg]

Hi Everyone!

I picked up a '77 about a week ago. It had been sitting awhile and I've had a number of things to do, here is where I'm at:

I've gone through the brakes and I think it's all sorted. Rebuilt 3 calipers, had to replace one. New discs and pads, they are ok for now, will probably need to be bled again.

Drained the gas and replaced all the fuel filters, the tank looks clean.

I rebuilt the carb, new wires, cleaned and gapped the plugs (they were in pretty good shape), and got a new coil (old one had some corrosion and the resistance measured wrong). The timing is set at 10 degrees.

It's a 32 ADFA carb and I'm having some issues with the idle. The choke seems to be set right and idles about 2200-2500. My low idle is off though, fluctuates between 1000-1500 and adjusting the idle speed screw doesn't seem to make a difference. At 1500 it idles pretty smooth, at 1000 it's rough and misses, I don't seem to have any input on what speed it decides to idle at? I've checked all the vacuum lines and they look good, emission is still connected though.

When it's cold, the acceleration is off and will die or backfire. Once warmed up it's great, although another problem - the secondary doesn't open much. It's not stuck, just seems like the mechanical linkage doesn't have enough travel with the pedal?

I received a shock today while checking the timing. I touched the distributor and got a jolt. Never had that happen before.

Lastly, it backfires on shutdown. Loud exhaust bang after it's been running.

Tomorrow I'm going to check:
1. Spray carb cleaner and look for intake/exhaust leaks
2. Cap and rotor don't look bad, but I'm going to check the points
3. Double check the choke in the morning when it's cool again
4. Check compression

Anything else you can suggest? I appreciate the input!

Steve

[kilrwail]

I'd suggest the idle mixture may be too lean, which would cause the symptoms you described. I've had this problem in the German car and making it richer at idle solved them both, especially the backfire at shut down.

[anothersteveg]

Thank you for the reply.

Any suggestions as to how much to enrich? I've read the tuning pages, and with the idle speed being off, I don't know how to guess the adjustment? I was planning on pulling the plugs and seeing what they looked like after a bit of driving, should've said that.

Anyone else?

Thanks!

[majicwrench]

Set idle as slow as you can. With car running (poorly) hold hand over carb to restrict the air a bit, does that improve idle?? Can you now lower idle with screw?? IF so, your idle is too lean because...
Should be alittle solenoid on side of carb facing drivers fender, it's the fuel shut off. It should have power with key on, and click when wire hooked/unhooked. If that works....
THe idle mix passages on these plug very easily. The tiny jet is under a hx bolt facing out to the drivers fender just under the air horm. Any blow-up pic will show it. There is also a secondary idle/slow jet on the opposite side of carb.
The screw is on the base of the carb to adjust mix. about a turn and a half should get you started.
Don't bother pulling plugs.
Keith

[anothersteveg]

Just a follow up.

I decided to go ahead and remove all the emissions. I then found a more detailed depiction on how to properly tune the choke and got that done, also realized I forgot to put the spacer on the carb when it went back together (buddy was over and it was a late night w/some beer involved). So I got all that done and when I went to start, nothing. Battery was good so I pulled the starter and it's toast. So I ordered one from Ricambi along with a new cap, rotor, points, etc. I figured at this point I might as well start with a clean slate.

Now I have to wait until I get back in town next week to put it all back together again. The good news is I found a couple more vacuum lines that were bad during all this. So that along with the choke and carb tuning, deleted emissions, and hopefully all will be well.

Steve

ps. Next step is straightening out the wiring mess. Any tips on that?