Running Poorly

[Hurtle]

1965 289 2V

About 100 miles from home, my car starts running poorly all of a sudden while navigating a parking lot at < 10 MPH speeds. Poorly as in really rough and can barely stay running at idle.

I managed to get it home and start checking things. I pull a few plug wires and find that #7 has no effect on the idle when removed. The wire was sparking though as I could see the spark jumping to ground. I pull the #7 plug and it's clean like brand new. I then swap #7 and #8 plugs and unexpectedly, the problem stays with #7. Just for the sake of being thorough I then swapped the #7 and #6 wires and the problem still stayed with #7. I then sanded the rotor and contacts in the cap and that didn't help either.

So I'm now back to the coil or Pertronix unit. The Pertronix unit is hooked to the coil side of the ballast resistor and that arrangement has been working fine for 8 years. The spark plugs are Autolite 45s if it makes a difference.

I just figured I'd post here for opinions before I swap the coil. What are the odds this is a fuel starvation problem that just affects one cylinder?

Thanks for your comments.

 

[Hurtle]

Update - Plug wires 1 and 6 have no effect when pulled off either. 5 and 8 do. So 1,6,7 are problematic and i stopped after that because I was getting burned.

Assuming half the cylinders were problematic, I turned the idle adjustment screws all the way in. Doing so on the driver's side stalled the engine as expected. Doing so on the passenger side had no effect. The gas shoots down both venturis when I pull on the throttle though.

OK. So it looks like the idle passages on one side of my carb are blocked up. Fair assumption? I'm suprised the car can run at all on half the cylinders. Anyway, would the next step be a carb rebuild or can I pass this thing like a kidney stone somehow?

 

[ashford]

ill bet #4 doesn't work either. sounds like half of your carb is dead.

 

[D.Hearne]

I'm suprised the car can run at all on half the cylinders.

You'd be surprised to know they used to use a 302 V8 as an air compressor in tire service trucks. Half the cylinders fired the pistons, the other half were the air compressor cylinders. You can remove the top half of an Autolite carb and look inside to see if there's something blocking the main jets. Take a peek and let us know what you find.

 

[Hurtle]

You'd be surprised to know they used to use a 302 V8 as an air compressor in tire service trucks. Half the cylinders fired the pistons, the other half were the air compressor cylinders. You can remove the top half of an Autolite carb and look inside to see if there's something blocking the main jets. Take a peek and let us know what you find.

I forgot to mention that. It's an Autolite 2100. The main jets aren't blocked. However, I did find a bit of silicon gasket material at the bottom of the fuel bowl next to the valve under the float (IIRC that's the power valve). It wasn't the culprit andI have no clue how it got in there.

 

[D.Hearne]

If you found one piece, there's probably more. Time to take it apart and look for it.