Spark plugs

What plugs are the best to use in a 340 6pak. Has anyone tried the E3 Plugs?

My 340-6 runs great on Bosch Platnums. I wouldnt waste my money on those E3s. IMO multipul ground electrodes may shroud the spark..

Working as a tech for at least 30 years.Worked on Mopars for better than 40 years.Run either Autolites or NGKs.I cant count how many sets of Bosch I had to replace because they were all total crap.I always tell people if you have them that run good go play Powrball.You are really lucky.Champions also run well in some Mopars.Rocky

Autolite. Running a 64 in my 340.

Autolite 65's or Champions in my old smallblock Mopars.

I have used the OEM plug heat range, N9YC non resitor or the resitor # RN9YC Champions in many 1968 to 1971 stock type 340 with great success I would use the better RC9YC now, they are the 5/8 socket plug size, a little easier to install That or the hotter RC12YC if your carbs. are rich at idle and part throttle In Autolite I would use either the #64 or #65 or the resistor plug # 84 or 85 Both brands should work well and there both easily found at most auto parts stores

Thanks, I am running autolite now and they seem to miss sometimes.

I was a Autolite fan for years, bought a fresh set for my 440 last year and boxes said Made in China. They lasted 2 months... Switched to NGK and love them, no looking back.

Mine are about 2 months also, 800 miles. I will look for USA made in some other brand.

I looked on the back of one of the E3 plugs, and they are made in China also.... I wont use them. I use and always used Autolite. Run them in everything I have, cars, trucks, tractors, go karts. As far as them being made in china, ive never seen those, but I have seen them from Mexico, and the U.S. my

Ive run Autolites since the 60s.Changed to NGKs in my 12.5 440 2 1/2 years ago.Seems a lot happier with them.Its street driven and the Autolites would develop a slight roughness after say 400 miles.The NGKs run cleaner also.Same set for almost 3 years now.Rocky