[wsd42]

Heres one for the real Techs guys (& girls) here at AFM.....Our GTs come with one temperture range Autolite spark plug (call it "0"), so if you Supercharge or Turbo Charge your engine, you are supposed to go to a "-1" or cooler SP. I am now seeing a "+1" or slightly hotter SP offered. Benefits??? Since I now do not plan (at least for a year or so) to SC my GT, but add under drive pulleys, hotter spark Coil overs, larger billet throttle body, possibly larger injectors (Recommendations/comments here as well), billet fuel rails (more for looks), in addition to the shorty headers, Borla exhaust, DSP tune, and Steeda CAI I have already installed. Is there any benefit to the hotter SPs? Thoughts, comments, etc...

[MSgt46270]

You have the part numbers wrong. The HT1 is the stock spark plug and the HT0 is the one that has the cooler range.

[wsd42]

I was not quoting a part number, just using the numbers ("0" as OEM, "-1" as Colder and "+1" as hotter) as reference points. Sorry if this confused you. So, with that said....any useful comments as to the heat ranges and their applications????

[GTRaptor]

Colder plugs are most commonly used when you increase compression, advance timing or add a sc or nitrous.

With basic mods, stock plugs are ok.
The best way to know is by reading your plugs, which can point to rich/lean - hot/cold conditions with which you will select a spark colder or hotter than stock.

The best thing to do considering a change in plugs, is swap for a stock heat range COPPER PLUG, yes, no fancy plat or iridium. Copper is hands down the best choice for performance applications.

Example, in my case, with a 625 RWHP SC'ed combo, you might guess i went "fancy", not so, i use 2 heat ranges colder COPPER Motorcraft plugs with great results, and no problems. I always keep 2 spare sets of plugs, in case i need to change them. And all for less than $40.

[wsd42]

I assume by "Reading" your plugs what I heard a long time ago:

White tip with no residue - burning ok
Blackened tip - running rich
Black tip with some residue - burning oil possibly

Since there are not too many manufactures of the SP's for the '05-'07 engines, we will have to stay with what Autolite is manufacturing (the three ranges - hot, cold, OEM neutral). I understand the colder plug to prevent detonation in a SC/TC engine.

Why would I want to run a hotter plug?

[Erjan]

ok this is a good topic since just recently i have a spark issue (i think).. the problem: mild bucking at idle and very light acceleration, at 1/4 throttle it fine... while it bucking, i get rich gas odor (like running rich) and while down shifting the car is backfiring quit extremely, as if the muffler has fire crackers going off.
what i have is a well built 306, b-cam, 24lbs, bigger mas/bt, trickflow upper/lower, trw forged pistons... for spark i got motorsport 42p (not sure what heat range), msd cap/rotor/msd 8mm and msd coil...
the question is, am i running the right plugs. i pulled out the pass rear plug out and it was clean (white/ no residue). i was told to run stock app. autolite 25s, but someone said to run a hotter 27s to burn out the fuel from the 24lb injectors. the plugs gaps where check .54 didnt need to gap.
any suggestions?????