1940’s 350 hot rod question

[Cannonballkev]

A buddy of mine has a 40’s hot rod that he got when his dad passed, somewhat finished.
Old school Chevy 350 carbed.
We got it running, but idles rough,
While it was running, he shut off the battery disconnect switch, it instantly smoothed out the idle.
We tested several times, smoothed idle everytime.
Any ideas what would cause this?
Thanks 

[Big Dave]

Is that Roger’s? Nice.
Are you saying that when you hit the disconnect it runs better?
It should shut off. Or am I missing something?
I’d check the grounds & remove the disconnect. It sounds defective.

[Cannonballkev]

Is that Roger’s? Nice.
Are you saying that when you hit the disconnect it runs better?
It should shut off. Or am I missing something?
I’d check the grounds & remove the disconnect. It sounds defective.

Yes, that’s what I’m saying.  Disconnect battery, then it’s just running off of alternator .

[extremetownie]

 I would check to see if it has a ballast resistor on the ignition.  In the older Dodges the ballast resistor allowed the engine to start with 12 volt to the coil, but run with 6 volt (approx.) The battery may be asking the alternator to put out more volts when connected, then when disconnected the voltage requirements would drop. Just a way out there guess. 

[8lugLJ]

Chevy 350? Swap it over to electronic ignition and forget it, go get a Streetfire with the internal electronics and the single wire hookup. Also be sure all your plug wires are shielded and you have plenty of grounds, block-frame, block-firewall, firewall-frame, never enough grounds.

[Cannonballkev]

Chevy 350? Swap it over to electronic ignition and forget it, go get a Streetfire with the internal electronics and the single wire hookup. Also be sure all your plug wires are shielded and you have plenty of grounds, block-frame, block-firewall, firewall-frame, never enough grounds.

You nailed it, re grounded everything, Running great on battery, as it should now

[Danny Kinder]

A buddy of mine has a 40’s hot rod that he got when his dad passed, somewhat finished.
Old school Chevy 350 carbed.
We got it running, but idles rough,
While it was running, he shut off the battery disconnect switch, it instantly smoothed out the idle.
We tested several times, smoothed idle everytime.
Any ideas what would cause this?
Thanks 

son of a bitch that's nice! Did he ever finish it? I'd love to see a pic on the road!!

[Cannonballkev]

We got it running good.  He ups still putting the interior together and cleaning up the wiring .
  His dad had lung cancer, was going in for an operation , before that operation he wrote a note to my Buddy (Roger) on a piece of cardboard and stuck it on the dash of things that needed to be finished.  He didn’t make it out of surgery and Roger didn’t find the note untill several months later when he went to haul it home from Raleigh.
  The note just said
“Roger, these are the things left to do” and listed them out.

Pic was taken a couple weeks ago.  I’ll see if I can get a side shot

[clark123456]

I love the note!  and I like seeing modern stuff on there, like disk brakes.