Spark plugs for my stang

[Xargon321]

looking at changing the spark plugs in my stang. i have the duraspark II with a msd 6a ignition box and coil and are currently running the stock copper autolites. was thinking of going to platinum but saw that a MSD tech guy on their forums recommends not using platinum because they run to hot with the msd box and to use a copper plug that is one to two steps colder then stock. no i know this is not a ford 6 he was talking about but dose the same still apply? what are good plug to use in my setup. thanks in advance!

oops almost forgot to as that the engine is a 78block with a 80 head and a carter Yfa carb if it make much differnce

 

[rbohm]

8) i agree with staying away from platinum plugs on engines not designed for them. i have used them and have gotten detonation issues that went away after i went back to the non platinum plugs. i also recommend going a heat range or two colder especially when running lots of initial timing and/or electronic ignition.

 

[Xargon321]

ok. so what would be a good starting point one or two steps colder?

 

[wsa111]

NGK iridium WR51X stock # 7510 & gap them at .050" if running a stout ignition system. Bill

 

[Xargon321]

Iridiums are nice but boy they are exspensive is there any gains on a stock motor with a duraspark II with Msd 6a ignition box over copper? also why did they suggest going colder plugs when using a msd ignition?

 

[wsa111]

Sure, the fine center electrode requires less voltage to fire, thus you can gap them wider than a regular sized center electrode.
The engine runs smoother cause there are no misfires.
I use them on all my engines & the heat range is ok even on a 10.5-1 compression engine.
They recommend going colder because the multiple hotter spark keeps the plugs from fouling.
The only time i would not use them is on any supercharged engine that is going to be raced. Bill