66 newport intermittent misfire

[Alexwesolowski487]

66 newport 383 3 on the tree been dailying it since the weather broke up here in the northeast, took it out this morning got a coffee dropped the son off to school and about 20 minutes into my commute to work it feels like I lose a cylinder, being only 10 minutes from work I brave the rest of the drive and low and behold 5 minutes later it clears up and doesn't come back. Fast forward to later on the day I leave work and do a substantial amount of cruising around and turning the car on and off running errands etc and no misfire. The Mrs. and I go for a cruise and all of a sudden misfire comes back and it's more noticeable than this morning, turn the car around and start heading home and sure enough 5 minutes later it clears up. Car is still points and I did plugs last fall before putting it away, any pointers of where to start digging would be appreciated, I can't imagine it's compression related if it's coming and going so I'm guessing it's spark related but being that it keeps disappearing I haven't been able to throw an inline spark tester on it

 

[CBODY67]

Might start with the spark plugs, looking for differences in ceramic color and such. Then look at the routing of the plug wires between the plugs and dist cap. Check for a failing condenser, too! Might just try a new one for testing, but NOS is better in many cases. Does the oil smell like hydrocarbons rather than just motor oil?

Take the car out for a 2hr run on the Interstate at 60+mph to get it hot, stay hot, and cook out some of the accumulated carbon in the combustion chamber. Plus make sure all of the old gas is used up (even if it might have been diluted a bit with fresh gas).

Just some thoughts,
CBODY67

 

[halifaxhops]

If it is a new parts store points and condenser.........Start there the points have terrible spring tension and the cond are hit or miss, usually act up in a heat cycle.

 

[65sporty]

Even though you replaced the plugs last year I would still give them a look. If the wires are an unknown, I would do wires also. Full tune up would be a great place to start, points, condenser, dist cap, rotor, fuel filter, plugs, wires, check the timing. I don't know how long you have had the car or how much you have done to it, but I like to do these things so I know what has been done.

 

[CBODY67]

Even though you replaced the plugs last year I would still give them a look. If the wires are an unknown, I would do wires also. Full tune up would be a great place to start, points, condenser, dist cap, rotor, fuel filter, plugs, wires, check the timing. I don't know how long you have had the car or how much you have done to it, but I like to do these things so I know what has been done.

Even IF the current items are doing decently well, you KNOW that at some point in time, they will need to be looked at. Might as well do it now and get it out of the way and move on to other things to deal with on the car's engine. I fully understand the issues with living in CA and dealing with emissions issues. Key thing is to determine WHERE the oil smoke is coming from, if from a leak getting on the exhaust system or from the motor itself, or both. The old comment "It's old enough to smoke" isn't funny in this case.

Please keep us posted on your progress,
CBODY67

 

[cbarge]

Get rid of the points, either go Pertronix or get a Mopar type conversion kit with ECU, harness, and distributor.
New points type parts nowadays are inferior Chinese crap , especially Condensors.
They crap out a lot unless you score NOS or NORS quality parts.

Hope this helps.

 

[Alexwesolowski487]

Coming back to update, simplicity seems to prevail I filed the points and here we are several days later without issue. 2 theories I have mustered up, 1 being of course the points and the 2nd being that I have never had to put more than 6 to 8 gallons in the car at any given time as the fuel gauge doesn't work so I stay on top of it. The day of the issue the car took 12 gallons so I am curious if it there was any moisture in the tank if it had gotten low enough to suck it up

 

[CBODY67]

Moisture and ethanol'd fuel results in "phase separation" where the moisture-fueled gunk settles to the bottom of the tank. Guess where the fuel pickup tube is located. That stuff can cause some flaky running, but not sure about exhaust smoke.

Just some thoughts,
CBODY67