I had To run to work Sunday morning to meet a customer.So he could drop his car off , and when I got home , I set in the front of the house for a minute just idling , looking at something and noticed the car was running kind of rough. Just pulled the plugs , and I don't know if i've ever pulled them after owning this car a year and and a half , and it sat for twenty five years before that. I put about six thousand miles on it since i've owned it. All the other Ignition is up to good standards.And i've replaced all of it including the dual points ,wires etc. Timing is at fourteen degrees off the bottom and thirty degrees total. This is a 1955 Plymouth , 241 V8 that has had the heads off of it to put in hardened valve seats , new guides in springs 30 years ago. What say you on these plugs. They are kind of white and ashy.
I'm also running cheap ethanol gas 87 octane. And I do have a PCv valve That's been there since before I owned it when the guy had to take it to get a smog, so maybe it's running lean?
It gets that everyday. I've got a hill that I have to go up.That's about half a mile long and it's full throttle the whole time.And by the time I get to the top it kicks down into first and screams for probably the last hundred and fifty feet so it gets cleaned out.
Thinking lean carb as this thing from the factory didn't have a pvc system.gonna get new plugs and check jet sizes tomorrow
I'd scrape the crap off them and put them back in, and see how it does. Doesn't cost as much as buying new ones. You say it's been several thousand miles of driving...did you do the other stuff to the ignition back then, or more recently? Because it might need the dwell/point gap checked again, and perhaps the condenser is getting tired?
Went through the ignition in March and checked dwell today and it's good.replaced condenser at same time with nos old kits.
they look about 30 years old, probably since the head work was done, I'd replace them and check again after a day or two. for me a regular tune up includes cap, rotor, points, condenser and plugs, coil and wires only as needed
If it is running okay, I'm not sure I'd do anything. They look like a lot of plugs I took out of good running engines, just some gas deposits.
In today’s world with current fuels , the plugs do not look all that bad to me . My 2 cents a tune up and slight jet increase , drive it until you get a real issue
I changed to marvel in place of ATF years back... I got a t bird 312 years back that had been sitting... I poured marvel down the carb till it filled..., then just let it sit for bout a month....I then pulled all the plugs and let it drain out... spun it on the starter till it quit spitting... put the new plugs in and got it to fire.... holy smokey batman... looked like the house caught fire....couldn't see the bird...
Over the years I've looked at a lot of spark plugs. I've seen a lot that were sooty and some that were pretty white. I've seen ones like in Brian's car. The only car I ever had that colored the plugs like the middle picture was a 54 New Yorker. The plugs were always picture perfect. However, my dad drove it for a couple of years around town, probably never got over 30 mph. The plugs would carbon foul. A good high speed run would clean them right up. Had to do that maybe every 6 months for him. Because we ran alcohal, the race car plugs didn't color much.
As mentioned, it’s not easy to read plugs like the old days. Best option is an AF gauge and base the meter reading off the type of fuel you’re using. Ie pre-ethanol fuel was 14.1? at cruise, around 13.5 WOT, if memory serves. @gimpyshotrods has posted before what readings you should try to get with ethanol fuel blends. Maybe he’ll come in and reply.
Modern ethanol fuel on the pump do not read like older fuel Formulas blend. The only thing I was ever able to get a Champion Spark Plug since early 90s to live in is a lawnmower and a Mopar & most where straight 6. Afr gauge will make it so much easier with ethanol fuels
Old plugs without any historic information. You stated they have around 6,000 miles on them, back in the points and old gas blends days, 10,000 miles on plugs was at the end of their usable mile range. Replace them. A J18 seems like a pretty hot heat range plug to me, and the plugs look a lot like the plugs second to the left, bottom row of the last plug reading chart. Without history of the plugs, any reading is going to be questionable. You have no idea what those plugs have been through.