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Recently tuned up my '54 Clipper Super 327CI/165HP L-8 with new points/condenser/rotor/distributor cap prior to a 300 mile road trip. Cleaned plugs and re-set plug gap prior to the trip also. With idle at 450RPM, timing is right on the mark per inductive timing light strobe. Car idles fairly nicely, but slight waver in the RPM, especially at lower RPM. I attempted to set the dwell at 31deg, but with 31deg dwell, idle at 450RPM and timing set per the strobe, the car became hard to start and would not idle without stalling. I reset the point gap to .016 with a feeler gauge, checked for correct timing with the strobe, idle set at 500RPM. Idles with a slight waver in the RPM, but idles pretty smoothly. When I increase the RPM, under load while driving, or in my driveway, the engine has a fairly pronounced 'miss.' Appreciate your thoughts in helping me diagnose this issue. PS--the fuel pump/carburetor have been rebuilt in the last two years, and the coil is about three years old (NAPA 6V). Thanks Again!

Bit of a long shot, but cross-firing between closely spaced (or touching) spark plug leads can cause this exact situation. Are the wires new? If not, I'd replace them.

Hmmm..the wires look ok, but they are at least 3 to 5 years old. I have had the car over three years, and I have not replaced the wires. I imagine they were on the car at least a couple of years before I bought it. I will inspect the new points for wear condition after having just completed my road trip and probably replace the wires per your suggestion. If I ran the car at increased RPM in a dimly lit or dark garage, might I see the spark 'leakage' you are referring to. Thanks Owen-D!

If I ran the car at increased RPM in a dimly lit or dark garage, might I see the spark 'leakage' you are referring to.

Worth a try, it only takes a minute or so. If the wires go thru a metal sleeve you might not see it but still worth the effort IMO.

If I ran the car at increased RPM in a dimly lit or dark garage, might I see the spark 'leakage' you are referring to.

Worth a try, it only takes a minute or so. If the wires go thru a metal sleeve you might not see it but still worth the effort IMO. If they do go thru a metal sleeve and you can easily do it, remove and reroute them and give it a second test, firing to ground within a metal sleeve isn't unheard of.

Thanks again Owen_D..I will give it a try. They don't go through a metal sleeve so it should be an east test.
-Warren

I had the same problem with a much older Packard than yours, it was caused by wear in the distributor drive shaft and bush allowing the points gap to vary widely. The car would idle and run at moderate speed but as the engine revs increased it missed badly.

Go back and read the FIRST PART of post #2 above. The wires should not touch each other on ANY engine of 8 cylinders or more.
The steel tubed wires are touching yes but der stell tube acts as a grpund to filter out e leakage.

Thanks DavidM and PackardV8...I will be trouble shooting the ignition cables as a possible easy fix. My last and more expensive resort will be rebuilding the distributor..which in my heart, I suspect, is the real culprit. In the mean time, it wouldn't hurt to sort out the ignition cables. Thanks again to everyone!
Warren

Went in today and cleaned the distributor breaker plate, cleaned the breaker points, and reset the gap, set the timing mark dead on with idle at 500rpm. When I set the timing, I did it with the vacuum advance disconnected at the distributor. I then increased the engine speed to high RPM with the vacuum advance still disconnected at the distributor..smooth as glass with no misfiring. When I reconnect the vacuum advance, and increase the engine speed to high RPM, the engine starts misfiring. Should I assume from this that I have a bad vacuum advance? Should I replace it, or just leave it disconnected (just kidding).
Appreciate all your further thoughts!