Packard Forum Index » General

I tuned my '41 Clipper (new plugs, wires, points, condenser) and she starts on the first crank and runs smoothly . . . until she gets warmed up. After maybe 10 miles she begins to run rough; I think I'm loosing at least one cylinder, maybe two. I've rechecked the plug wire connections and they seem fine and they all snap when connected to the plug and cap. Could I have a bad plug, or could the gaps be ok when cold, but incorrect when warmed up? Help!

First thing I'd do is to replace the coil and retest. Just pick up a universal 6-volt coil and install temporarily.

Also the new condenser could be opening when hot.

We had the same experience with our 51 henny. new every thing. plugs,wires,cap,rotor,points and condenser, and coil. it turned out that there was to much resistance in the coil wire, and as we all know, electricity seeks the path of least resistance. it was arcing back to the coil housing, or any place it could arc to.

i noticed while uncle had it running, i could hear the electric "snap" we shut the lights off in the shop, and then you could see the light show around the coil/coil wire.
we have recently seen this issue re-emerge with customer's cars.

try checking it that way and see what you get.

I had a similar experience that was baffling. Everything was new, gapped properly, timing and dwell set by a friend with proper equipment. When warmed up and driving it would start to miss.

What fixed mine was I loosened the distributor, advanced it a bit then tightened it back down and everything went good.

I discussed it with my local mechanic today and I brought up the possibility of a weak coil. It tested okay on his meter. It's an Autolite system and the coil only has a hot connection. We assume the ground is through the housing via the screws into the firewall. He suggested cleaning the area and reattaching the screws to make sure of a good ground. He thought that maybe after running awhile, it could be breaking down, possibly because of a less than perfect ground. Tomorrow we are going on a cruise that will cover about 125 miles so I'll report back . . .

Denny, There are two wires to the stock Autolite coil. One is at the back of the coil under the metal cover and inside the shield cable which you will find when you remove the coil from the firewall. This is the anti theft ignition switch wire. I think that if this is the original or old replacement coil this could be your problem. I had the exact same problem with my '47. Ran fine until warm and then miss. A new coil fixed that. I doubt you will find a coil like you have that is new so you may have to find an alternative mounting location.

Thanks clipper47, I will probably be shopping. What about rebuilding it? Max Merritt has them if you send a core. Good idea?

Quote:

I would just try installing a new coil just to see if that is your problem before spending the dough on a rebuilt one. If it is the coil you and are concerned about absolute authenticity the rebuild would likely be your best bet. What I did was find a bracket that would fit the mounting holes and installed a much less expensive regular two pole coil in the same fire wall hole. There was room to splice a wire to the the shielded ignition wire. These brackets occasionally come up on Ebay as they were used by Chrysler and possibly others as well. I may even have one in my parts bin but will have to look around and see but I have seen them for sale quite often.

If this wasn't happening before the tune up, then I would seriously consider the replacement parts. My first thought would be to check the point gap and distributor for wobble. If the points are set a tad "wide" the gap will increase as the components heat up and expand, thus possibly causing a miss. You could reinstall the old condenser to see if that is the culprit as well. Also, check the new rotor to see if there is a resistor built in that could be causing the miss. Lastly, I would examine the distributor cap to see if it is cracked or shorting. I have had new caps with faulty "casting" connections that caused internal arcing after the engine heated up.
If you know someone with an older "scope", they should be able to hook it up and see what the spark pattern looks like and pinpoint the location of the miss.
HTH,
John