340hp sparkplug choice

[cudaman51]

whats a good spark plug choice for a mild 340 stock cr. and cam. are the champion rn9y outdayted or still a good choice.

 

[AdamR]

autolite 65s is what I use.

 

[moparker]

Autolite. What Adam said.

 

[beepahh]

champions RN9Y

 

[stroked 340]

Autolite..i wouldn't put champions in a lawn mower...

 

[Robzilla]

I run Champion plugs in all my Mopars and they work great!

 

[abodyjoe]

i lile autolite plugs.

65 is probably what it calls for.
66 for a slightly hotter plug
64 for a slightly cooler plug.

 

[flyfish]

NGK 5671A-7, stock# 4091 (I think...pulling from memory) for everyday driving. I used the -8's (stock# 4554) and -9's (stock# ????) for nitrous use on the old motor, but the new stroker likes the -7's.

 

[cudaman51]

the reason im asking i ran down the strip and it didnt do very good. it broke up at high rpm. 2.2 60 ft 91mph 15.2. 1/4. My stock 273 did 14.7 in the late 60s.needles to say i wasent happy so its time to go over the details. Its close to stock, hp. manifolds. i think it should do a lot better than that