There is no need to spend big money for magic spark plugs, and there is no benefit to doing so. The trick plug for regular use in a '60-'74 slant-6 head (w/spark plug tubes and gasket-seat spark plugs) is NGK #ZFR5N, which has projected electrodes to move the spark closer to the middle of the combustion chamber, away from quenchout and shroud areas. This plug design was developed by the major reputable plug companies in the '70s in cooperation with the automakers who were trying to get their newly-desmogged engines to run acceptably. Moving the spark away from quenchout/shroud areas made for more reliable ignition of difficult-to-ignite, borderline-lean mixtures. First application was AMC 258s. First Mopar application was '81-'83 EFI Imperials, and there are numerous more recent applications (4.0 Jeeps, 3.2 and 3.5 LH cars, etc.) Cost is the same as any other regular NGK plug, and they come
without any of the bullѕhit used to hawk E3s and other scam plugs. Remove the metal ring washer before installing each plug if you're using a '63-'74 head. If you've got a '60-'62 head, leave the metal ring washer in place. See
here for details on the ring washer issue.
The Chinese-made E3 plugs are a scam, just like every other "magic spark plug" scam in the last eighty years or so. Nothin' new under the sun. Wayyyy back in the days of gas price wars that started at 29¢/gallon and went
downward from there, JC Witless had full-page ads hollering
RUN YOUR CAR WITHOUT SPARK PLUGS! Back then they called 'em "fire injectors" rather than "E3", but the baloney still smells the same.
The claims made for what they do and how they do it don't square with any reality we live with in this universe, and are easily debunked by any 8th-grader in the top half of his science class -- and some of them (such as "the spark plug hasn't changed since 1904") can easily be squashed by the kids flunking everything but Smoking Area.
As for the magazine "test" of E3 plugs: Yeah,
no doubt.
Think: automakers spend enormous sums of money to squeeze every last possible bit of fuel economy and efficiency from their engines. If these (or any) magic spark plugs did even a little bit of what they're claimed to be, you would see them as original equipment. You don't. There's a good reason.
