Spark Plugs

[Tom in SW VA]

Other than the Champion X plug, what spark plug have you had most success with? I'm using Autolite 66 and am not real happy.


Thanks.....

[J Franklin]

"Not real happy" is way to subjective to be able to give a good answer. How worn is the engine? What seems wrong? Give us at least that.

[Tom in SW VA]

Originally Posted by J Franklin

"Not real happy" is way to subjective to be able to give a good answer. How worn is the engine? What seems wrong? Give us at least that.

Thanks for your reply. The plugs that I am using (Autolite 66 with adapters) are fouling (black) terribly. I have checked the compression and it is good. I have changed the gap to .035 from .025. If I clean the plugs after every ride, it runs well. If not, it misses. The engine has a high compression head with the regular electronics; magneto, commentator, coils, etc.


I am just searching a solution. I am a fairly new with Ts. I am quite familiar with As.


Tom

[40 Deluxe]

If it's oily black, it is from burning oil-worn out rings most likely. If it is dry black it is running way too rich, which means carburetor is bad.
Generally when plugs are fouling, a larger plug gap is better because a higher voltage is needed to jump the gap, which helps burn off deposits.

[39portlander]

could a worn cam or standard grind 250 have similar dry black deposits with a high compression head installed due to poor or not enough valve opening with that head configuration?

I ask because I have an older high comp head and thought it would be better paired up with a 280 grind cam, any input would be great.

[J Franklin]

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Try a hotter plug and try to adjust the carb for a leaner burn if you can. I think the X plug works well and looks correct. Do the adaptors allow the tip of the plug you use to enter the combustion chamber?

[Royce P]

This might help:
https://modeltfordfix.com/model-t-sp...he-enthusiast/

And this:

https://modeltfordfix.com/cleaning-t...rk-plug-t1386/

Watch eBay. The best plugs are old originals from when the Model T was still being driven every day. Personally I like the Firestone E100F Polonium plugs best, followed by AC #26, and of course original Champion X plugs.

[Low Compression]

I run the new style Champion X plugs on 5 different T's. They are gapped at .025" and clean them once a year whether they need it or not.

[CharlieB]

Their turning black for a reason. (really ?). Usually only 2 things as stated above: oil or running rich. Are you blowing smoke and if so what color is it? Blue is oil black is running rich/fuel. You say the comp is OK. I'd like to see some numbers. In my book 45 or better is OK and would make oil burning (worn rings) a lot less likely. What year & what carb are you running? Going with an incorrect needle valve adjustment here because it happened to me in my early T days. Sooted the plugs up so badly it wouldn't run. Being new to T's at the time I couldn't imagine this happening and couldn't figure out why it wouldn't run. When pulling the plugs for a comp test (out of desperation) I found the problem. As to the plugs: changing to another brand won't solve your problem as something else is going on to cause the coating. Adaptors work as do X plugs in a properly running motor.