How are your Plugs Burning?
The picture to the right shows a comparison of the replacement plugs with the Original 3X and a NOS C-4 porcelain (just for more reference). The BEST match for the Original 3X turns out to be the W18. The second is the TT10/3076, which appears to be a little better match with the C-4 and then the W16Y, which is the COLDEST of the plugs. Also note the hair crack in the above C-4 porcelain. This could cause a misfire plug.
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