Slight Miss After Plug Wires?

[sigchuck]

Hi guys, I was in the process of backdating the heat on my 83 SC and decided to replace the plug wires while I had the AC compressor off.

The engine appeared to have the original Beru plug wires (stamped "W Germany" on the insulators), so it was probably well past time with 150k on the clock.

I used Clewett wires and I've double checked all the connections. I *think* they're all firmly seated on the plugs.

The engine runs fine and seems to drive alright, but it definitely seems down on power and I think sounds a ta bit rougher. I'm also detecting an occasional very quiet pop while cruising. As they're Clewett wires, they're very conveniently labeled, so they're definitely on the right plugs/distributor cap location.

I'm hoping you might be able to help with some questions:
1. Would the engine still run okay with a loose plug connection?
2. The brown ground wire coming out of the harness and attached to one of the studs on the coil bracket is loose. Unfortunately the stud is stripped and I don't have a ring connector big enough to replace it, though I will when I can get to the parts store. Does anyone know what this ground wire is and would it affect running?
3. Any other thoughts on what the cause of the rough running might be? If the plug wires indeed had 150k on them, is it possible the fuel mixture could have been overrich to account for poor wires?

Thanks for your help!

[MichaelSJackson]

1) Check again. Not only are they on the plugs, but are they deep enough in the distributor cap?
Same for both ends of the coil wire? New wire ends are often a bit big and don't seat deep enough.

2) Run it in the dark and look for little blue flashes?

[gomezoneill]

Are you talking about the ground wire that comes off the coil?

[sigchuck]

It's not the actual ground from the coil, but rather a wire coming from the bundled engine harness that's grounded to the coil mounting stud.

I pulled all the wires and re-connected a number of times until I was satisfied I had a good connection and also was able to tighten the abovementioned ground wire (though still not sure what it grounds). The car seems to be running great now. I'm kind of shocked it was running at all before after testing resistance (or lack thereof) on some of the old wires.