Finding the right spark plug for your 340 or 440 HP ..

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Mudd340

Mudd340

mudd340
Joined
Sep 15, 2011
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If you go to the parts store and ask about plugs for classic mopar or street rod 340 - 440 - 383 etc your probably not going to get the right plug from the parts guy and usually to cold ., If you ask about Heat range forget it ..
Numbers ? some higher numbers mean colder in some brands and some lower numbers mean hotter plugs which do you choose ? :prayer:
 
Champ RN12YC or Autolite 63-66's (heat range, all seem to have good reviews) I always used Nip U-groove and a .050 gap with MSD electronic ignition.
 
I've been using Autolite plugs for 30 years.
BB Mopar #65 SB Mopar #86.
Those 2 plugs seem to last the longest, and run very well.

Good Luck!

George
 
factory specs for 72 340
ignition timing 2 1/2 btdc
spark plug [email protected] 340 had electronic igition in 72 so no dwell or gap specs
idle speed manual trans 900 cali only all others 750. auto 750 in neutral
 
Thanks Guys heat range tho on those is about 5 or 6 .. ok for warm dry weather .. But truth is they no longer make the correct plugs ur using 318 2 bb plugs and 440 RV plugs
big difference .. on heat range . Thanks PS not all of us Have $$$ for crappy MSD system
which had almost last as long as those plugs .. less than a year ..
 
I don't know where you got this info from, but, for example, the Autolite #86 is the plug recommended for 69 Corvette with SHP 350. Maybe the application is the same for 318 engine, but that doesn't mean it's a "low performance" plug.
Best of Luck to you if you decide to spend unnecessary funds on a "drag race" spark plug for your car.

George
 
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