Reading my sparkplugs after 22k miles of use

[JM 35 Sedan]

Going over my '35 fordor in preparation for driving to the EFV-8 C/A Central National Meet in Springfield, Illinois next month. Today I decided to remove the sparkplugs (Champion UD16) to get a reading on their condition after running ~ 22k miles on a rebuilt '35 21 stud babbitt main engine that has been bored + 0.030 over the original 3-1/16" bore. I was surprised at how these plugs look. Would be great to get some feedback on what some of you guys think. I am hoping to attach some pictures I took with my cell phone. Probably not the best quality, but hopefully good enough to show their condition. I am wondering things like running too rich, to lean, or just right? Burning oil or not, etc.

[42merc]

They look perfect to me.

[41ford1]

I think you've got the state of tune just right. I'd be tempted to gap them and put them back in. They should be good for another 25K. Go man go!!

[Binx]

Now I'm jealous. After 22k mi those look great!!

Lonnie

[JSeery]

What CR are you running, any idea? I would replace them as plugs break down fairly quickly, but they look really good. The higher the CR the faster they break down but it's hard to get a very high CR on a flathead.

[JM 35 Sedan]

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Originally Posted by JSeery

What CR are you running, any idea? I would replace them as plugs break down fairly quickly, but they look really good. The higher the CR the faster they break down but it's hard to get a very high CR on a flathead.

I know the CR is higher than stock. We shaved the decks ever so slightly, milled the heads just enough to make sure the surface was flat (no record now of how much material was removed on either operation). Ol' Ron will love this part....we didn't think to CC the heads, just made sure we had valve clearance, and put it back together. All I can say is for a little 21 studder, this baby runs good and strong. No need for a bigger ci engine.

[AnthonyG]

Text book perfect, that is the way they are supposed to look always. I think you knew that though! Regap em, Put em back, and keep going!

[BUBBAS IGNITION]

Looks great to me !!!!!
Replace with new ones just like them and drive another 20,000 miles.......

[Blownflatheaddeuce]

Looks Ok to my eyes, gotta love them 21 studders

[FL&WVMIKE]

Sure look good to me !
Is "JM 35 Sedan" just bragging ? LOL
MIKE (mikeburch)

[ford3]

they look perfect, clean, re gap and run them some more, the days of replacing plugs every 25,000 miles are a thing of the past, since the lead was removed from the gasoline, there is nothing in it to foul the plugs, new cars go for over 100,000 miles before the plugs may need to be changed, this is like changing oil every 1000 miles, if you have a filter you can go safely 3000 miles or more, todays oil is at least 5 times better than oil even form 10 yrs ago, and we don't run on miles of dirt roads like back in the 30's and 40's

[JSeery]

It's not just the lead, the plugs themselves break down. If you have ever seen plugs placed in a tester you can see how quickly they breakdown, it is amazing. There is a major difference between modern ignitions and the older systems. I run the plugs in my 2005 mustang for almost 100,000 miles with no issues. On my 67 mustang the plugs started to break down after a few thousand miles and changing them made a big difference in performance. The CR makes a lot of difference also, the higher the CR the bigger issue it is, so a low compression engine can run longer on the same plugs. It would be interesting to have the plugs tested and see how long they will hold up at the lower CRs.

[ford3]

I doubt it was your plugs, it is your ignition system failing, probably your coil or plug wires, spark plugs are manufactured to higher standards and with much better materials than in the 40's or50's

[JM 35 Sedan]

Originally Posted by FL&WVMIKE

Sure look good to me !
Is "JM 35 Sedan" just bragging ? LOL
MIKE (mikeburch)

Yeah Mike, that's right, just a big show off LOL....actually I was concerned that maybe they were too clean, maybe carb set too lean. They were all gapping at about 0.035" when I took them out. Cleaned the electrodes, regapped all back to 0.025" and put them back in. I would have liked to tested them as JSeery suggested, but had no convenient way to do that. I always carry a spare set with me during my travels.

[ford3]

if the plugs were to lean they would be almost white, what your trying for are plugs that are a lite tan

[JSeery]

Originally Posted by ford3

I doubt it was your plugs, it is your ignition system failing, probably your coil or plug wires, spark plugs are manufactured to higher standards and with much better materials than in the 40's or50's

I was referring to testing plugs in a tester at a dealership. Had a friend that worked there and we would test the plugs (out of the car). If you were ever around race cars there is a reason they change the plugs, it makes a difference! When we raced the plugs where changed very often.

[ford3]

lol, we are not racing cars here, this is every day driving

[Mart]

I'd gap them and stick them back in.

But you knew that already

Mart.

[JSeery]

Originally Posted by ford3

lol, we are not racing cars here, this is every day driving

Quite true and I doubt the low CR flathead much cares about fresh plugs. Cleaning the plugs will obviously work, but I would change them. If you don't want to spend the money, any decrease in performance would be so small it would be insignificant. It's just the engineer in me, I like to worry about these type of things. Most folks are fine with good enough and rightly so. But then some are interested in the theory of how these things work and what is optimum.

[ford3]

fair enough, but most of us in here are not engineers, just back yard mechanics that learned to work on these engines the hard way, trial and error, finding out what works and what doesn't, and most of the time good enough is good enough