Gerald Morris
Senior Member
Tell us how you like 'em!
spark plug recommendation for a 70 440 TNT
- Thread starter marko
- Start date
Tell us how you like 'em!
70NEWYORKER
Well-Known Member
The 14's are a hotter plug than the 12's
70NEWYORKER
Well-Known Member
Gerald Morris
Senior Member
OK, THAT WAS THE DATA I NEEDED! I wonder WHY though the 12s would ping, but the 14s don't? I ran 11s when I had a batch of those even, with some racket. Why would the FSM spec the 14s for a 2 barrel carb and 13s for the 4, or 10s for emergency vehicles?
70NEWYORKER
Well-Known Member
Different compression ratios and time spent at high engine speeds/temps.
oldkimmer
Active Member
I have never ever had a problem with Champion spark plugs. I’ve been using them from the mid 70s in all my Mopars from stock, mild to wild. My last engine dynoe’d at 655 hp and 620 tq. I tried other brand plugs and always went back to Champions. Kim
Gerald Morris
Senior Member
Oh I've found Champion plugs to be the best for the 383 and 440 I had 16 yrs ago too. I've tried Bosch and Autolite in addition to Champion and have found them the most agreeable with my 383 in particular. Be this as it may, the modern J12Y recommended by Rock Auto for a 2 barrel engine would give me some pre-ignition pinging, while the NOS J13Ys and even smoother, the J14Ys make that old motor purr ever so smoothly. This has been the little conundrum which has irked me some, and led me to wrongly conclude the plugs are rated hotter with the lower number.
Anyway, if I should exhaust my horde of old NOS J14Ys, I may try the modern J14YC as a replacement.....
Last edited:
Ghostultramarine
Active Member
Okay, what is going to be the performance difference or actions of the RJ14YC vs the J14Y?
I have a small stash of these from my dealership days.
Waiting for that special car.
Waiting for that special car.
ive installed the NGKs and so far am happy with them, no issues or concerns
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