66 Newport random misfires

[Alexwesolowski487]

Okay to start i haven't begun digging in yet so feel free to chastise me but just haven't had the time with life lately so bare with me. Car is a 66 newport, 383 3 on the tree still running points ignition. Couple weeks ago i was driving the car and all of a sudden it just started shuttering like it was only firing 2 cylinders, put the clutch in at it came right back instantly, couple of the times it would let out one good POP out of the tail pipe which leans me toward ignition issue instead of fuel delivery. This happens a couple more times over the past couple weeks with seemingly no rhyme or reason, not when the car is hot or cold or holding a certain rpm or when hitting a pot hole or any specific situation of the sort. Couple days ago i fired the car up to move it made it 2 blocks and it just keeled over and died, pulled over let it sit for a minute went to start cranking it and it would just skip and sputter and occasionally fire off on what sounded like 3 or 4 cylinders and die. Couple minutes later it fired up fine and drove home 30 minutes without issue. Fast forward to this morning and i wanted to get the car out one last time before winter to get a full tank of gas and fuel stabilizer in the system and it just did not want to fire off, cranked fine for 30 seconds (not consistently, on and off to not burn up the starter) then started cranking real slow like the battery was on its last leg, then randomly would speed up cranking and fire off 3 or 4 cylinders and die, then right back to real slow cranking and i mean REAL slow. It eventually fired off incredibly enough and made it 20 minutes to work without issue. I did check the connections at the battery and ground at the other end of the ground cable and neither were loose or severely corroded.

 

[Toolmanmike]

Just as a guess I would say a bad condenser. If you decide to replace ignition components, get them from Halifaxhops. He has the old "good" stuff. The parts you buy at the store nowdays (especially condensers) are not good.

 

[Fury1969WI]

agree, sounds like an ignition problem. Haven't had points in 30 years, but if you haven't cleaned/inspected and gapped the points in last year or so maybe start there. burned / fouled points could mean bad condenser. good luck and happy cruising!

 

[CBODY67]

I'm wondering if it is really just a few cylinders that hit intermittently, but feel "random"? Only way to verify that wuld be to use an ignition oscilloscope as it will display the firings of each cylinder, in its sequence, visually. THAT, to me, would be the only way to determine if the misfires are truly random or as I mentioned above.

The scope can also allow you to watch/measure the dwell of each cylinder'[s firing, too. That would lead to the same plugs being intermittent, possibly. Only way to fix that would be a new breaker cam for the distributor (with all of the peaks being the same height and non-worn).

I WOULD be concerned about the "slow cranking speed" as that can point to a few other things. Like the battery cables being of the correct gauge of wire. Not to mention the condition of the battery and alternator. Maybe even the integrity of the connections for "the big red wire" going to the ign switch and through the bulkhead connector.

Chase the misfires FIRST. With a known-good condenser to replace the current one.

Keep us posted on your progress,
CBODY67