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This could end up becoming a process of elimination but you are on the right track. Check the plug wires as well. If you have an ohm meter, that would be the way to go.

Hibbing_Coronet_500 Wrote:Update:
FLIR camera shows a cold cylinder. Passenger side #2 from the front.
Timing light shows no movement of the mark at idle through the shudder. Just as you pass through the shudder the mark jumps.

So? Would a worn distributor cause this? Also the miss doesn't help either.
Gonna can the Taiwan dist cap and rotor and get mother mopar ign parts.

Thoughts?

Which way does the mark jump?

Jumps to advance.

We have a result!
After supper I went back out to the garage and pulled the #4 plug wire for giggles.
Started the car and it ran and idled the same. I ran it up through that "SHUDDER ZONE" It shuddered all the way up to 2000 rpm. I hit the key to off!
It shuddered like a dead miss!
So I have a low rpm miss fire?

Im going to wait on any other tests untill I get QUALITY IGNITION parts installed.

Sounds like distributor...get an MP electronic conversion.

I have the MP distributor. I tore it down and all looked fine. No gum or goo. Springs (pink) intact.

A Quik test............ Swap the wires from cyl. #4 and #6 at the cap and plugs. Run the engine and see if the exhaust temp goes up on 4 and down on 6. That way you know if it's just a wire. If the miss stays at #4 you may want to do a comp. test as mention earlier.

Will do!

Another update.
Tested cap and wires against the new replacements. Not much difference
Pulled the plug out of #4 hole and took my DVOM to it. Measurment showed open from tip to center electrode.
Ive worn plugs out. Never had one go "open"

Im sure the low speed misfire was due to low voltage at idle and it would jump the gap inside the insulator to compleate the discharge at a higher rpm.
Would that be a safe asumption?

gotta run for new plugs.

Frustrated!