Occasionnal rough idling and misfire

[frankfou999]

I have a stock '72 with everything original (coil, distributor) and sometimes I have this rough idling, misfire and lack of power. I changed everything from the contact breaker to the leads, the rotor and distributor cap and it happens again. What amazed me is when I pull the lead from certain plugs the engine doesn't react and if I just put the wire wire close enough for the spark to jump on the plug then everything goes back to normal and if I put the wire in place then the rough idling comes back.

Any clue ?

[madkaw]

I think I would try replacing the spark plug wires if you haven't already.Some how the shielding my be screwing with your spark. Are these custom made wires?

[frankfou999]

I think I would try replacing the spark plug wires if you haven't already.Some how the shielding my be screwing with your spark. Are these custom made wires?

The wires are brand new and from the highest quality I could have at UAP/NAPA. The very strange part of this is that it looks that when I pulled the wire away from the plug just enogh to have the spark to jump to the plug instead of the direct connection, it solves the problem.

[madkaw]

That is Murphys law hard at work. If these wires were already assembled I guess I would go back to checking connections and tightness of the plugs and their tips. Good luck!!

[Coastieee240z]

If it's sporatic like that check the point gap. Happened on my 72 once as well. I replaced the wires, plugs, cap , rotor, tried different coils. I even adjusted the timing and it got better a little after that then it got worse again. I didn't even think about the points. A friend told me to check the points and when I did there was no measureable gap :eek:

[frankfou999]

Hey guys ! I finally found the problem. A worn distributor shaft. It had a slight slack sufficent to lose the timing occasionally. Replaced it with a rebuilt one and the problem is gone.