I drove about an hour today, varying from 60-70 MPH in my car - 330, Q-jet, bone stock - and the motor started running very very rough. Would not stay cranked, and sputtered some and backfired a couple of times when I wasn't revving the motor.
Sounded like it was only hitting on 6 cylinders.

I believe I had the dist/rotor/plug wires/plugs replaced 6 mo or so ago right after I received the car. The car has been in the body shop, and I just got it out a few weeks ago, so it has only been driven much (~400 miles, maybe) over the last 3 weeks.

Could a rich mix have fouled the plugs out that quickly?

Anyone have any suggestions as to where to start?

 

possibly coil to distributor wire?

 

Do you still have a points ignition, my Cutlass suffered sudden unexplained crappy running after running great two summers ago, real rough running. It was the condensor. I did the usual checking of carb, points then replaced condensor. They can and do suddenly crap out.

 

I have an olds HEI I was planning on dropping in at an opportune time - this is probably going to be that time. All signs point to ignition problem, including a worn and weathered coil under the hood.

 

If your choke was sticking closed or something like that to cause an extreme rich condition, the plugs will foul in a hurry and the engine will run like crap.

If they look as bad as these:
https://classicoldsmobile.com/forums...html#post71550
Then that is your problem and you would need to find the root cause of the fouling.

Pop the disty cap to look at the cap and rotor.
If any were a poor quality, then it would be evident.
I had a new cap on a 4 banger fail in about 1000 miles (alum. terms) - i put back on the original and it has been running ever since.

 

Dropped in an HEI today - runs better than previously; solved my problem

now if I could only figure out an annoying, intermittent, upper engine tick/knock