Good call we did not go back too the basics yet.
I am thinking this also or something in the electronic side of the primary ignition. the Pertronix magneto or what ever type ignition they use. Is there an air gap ajustment? I would think the module if it was electronic. i would do the distributor cap off turn the crank and see how much slop in the chain before tearing it apart. start easy then tear the engine apart but dont go straight for engine internals. It could be electrical. How are the grounds for the ignition? any High resistance connections?The vacuum advance can cause instability even when disconnected.
How many shafts are there? I thought the oil pump drive shaft has the gear on top to be driven by the cam. There is a slot in the top of the gear that the distributor shaft indexes into. I don't understand what the intermediate shaft is?The shaft for the oil pump was raising and lowering. A collar shaft locks the iISHAFT AGAINST THE SDIST SHAFT SO IT CANNOT GO UP AND DOWN ANY MORE. If it goes up and down it will definately affect the timong because it is a spiral gear mated to the cam so it will advance and retard as it does it. On a dist machine it locks the shaft and housing in no bouncing. I would look at cloys or a similar brand for the timing set. You will spend 100 on a quality set for sure.
I know stupid.
I think most everybody on here knows we're acquainted.
Yup..never rule out electrical. I only say that because I also worked avionics on A-10s in the service, as well as did my stint at a dealership working electrical issues in cars. i had my dart running recently, and the Auto meter tach was erratic, I thought "w t hell is the ignition system crapping out? as it is wired into the negative side of the coil. It cleared out and started running, but I am waiting for it to happen again.Had this same issue on my Dart, it turned out to be operator error. One of my plug wires wasn't fully seated. Timing jumped around exactly as you said and once I went through all the nightmare scenarios I found one ignition wire that wasn't "clicked" tight
3) I measured chain slop, yes there is some but it seems minimal without a degree wheel on the crank to put an actual number to it. .
check for timing chain slop, anything more than a 1/4 inch is too much. try disconnecting the vacumn advance then see if it jumps around. it could be that its starting to pull the distributor at idle.
i assume that is jumps around at all rpms? or just at idle? Also check the reluctor on the distributor. I had a jumping around problem once turned out the reluctor on the distributor looked like a bunch of mice had been chewing it. Changed the reluctor and the jumping stopped.
how many miles on the motor?
Have you tried connecting the light to another spark plug wire and see if it still jumps? Possibly something wrong with #1 plug wire .
They are called that also the oil drive shaft. I know stupid.
For 1963-1964 Dodge 440 Oil Pump Intermediate Shaft 58663DX Stock | eBay
You know i would not think a reluctor could go bad but maybe, you do have current jumping at it alot. But that is a possibility. I would never have guessed. I would think the magnet part which i think is called a phaser correct me if im wrong.