What spark plugs are you currently using?

I have run 3Xs in the past but now run W-18s. The W-18s run a little cooler than the 3Xs with my set up.
 
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Champion W18 set at .035 with a Snyder's 6:1 head. Just pulled them after the first 2000 miles, looked great... Chap
 
I have used Champion C-4 with good results . The Champion C-4 plugs haven't been offered in many years . I like the look of the two piece Champion spark plugs. Most comment on the two piece plugs and think that they are original . There is a huge difference in the price of of The Champion 3- X and C-4 spark plugs . The C-4 plugs don't seem to be too cold and run clean in the model A's that I use them in. I sometimes buy new old stock C-4 spark plugs when I can find them . Champion W-18 spark plugs are readily available and are thought to be the same heat range as the original 3X but aren't two piece spark plugs like the 3-X .
 
Back in the day (50's-60's), C-4's were considered the standard plug. How times change!! I had never heard of a 3-X until last year when I got back into the Model A world.
 
The first set of spark plugs that I bought for my model A was Champion C-4 . This purchase was over the counter at Thomasville Auto Parts in 1960 . The metal part of these spark plugs was zinc or some such silver colored plating like modern Champion spark plugs . These spark plugs cost maybe sixty something cents or less each . I decided to try these old used spark plugs again after all of these years . I cleaned and gapped the plugs and installed them in the same model A that I got them for 59 years ago . The model A cranked right up and seemed to run pretty good . I decided to remove and replace the C-4s with Champion W-18s . I think I'll try the C-4s again if I need Them . I think that most of us change the spark plugs way too soon in our model A's .
 
If you all make any big changes to your spark plug choice please let us know why. I think this thread has given me a little insight into spark plug selection.
 
This is like many Model A subjects. Since it is not fuel injected, no sensors, not electronically controlled, what works best for one car is not what is needed for another Car. So you tune/adjust the best you can, and choose a plug that works best for you.
 
That's a very sharp statement from 30 CCP!


The low compression and the coarse carburetor as well as the rarely optimal ignition point result in never optimum stoichiometric combustion.

Even the unregulated huge cooling water system and oil volume can not run the engine in the favorable operating temperature. Therefore, sooty spark plugs, once brighter, sometimes darker, are just as normal as a clutch that jerks something, a gear that sometimes scrapes and a wobbly steering.

This is normal for a 90-year-old car, so it pardons many of the mistakes, that modern engines would kill if they did not have 1000 electronic guards.

You have to drive with it, you have to be generous and tolerant like with your beloved old frail dog who does not hear well anymore and sees and hobbles.

That's life with our old iron car "Model A"!
 

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