It's not confusing - they are different stock applications. One is naturally aspirated and one is supercharged. The combustion chamber temperatures and pressures are vastly different.
There's no magic to spark plugs. Basically you want to run as cold a plug you can without fouling. You could jump right in the deep end of the pool and get the 103s or the Lightning plugs for your N/A stock engine.
What you should do is run a set of plugs(32C) awhile and then inspect them. Change them out for a one step colder set(22C) and repeat. When the plugs start fouling(12C?) - go back one step hotter to prevent fouling. Everyone's experience will not be the same.
According to the article, and autolite 103's are one step colder. I have them, they ran well with out my tune on. but when the tune was added the engine revved slower and there was a definite power loss. so i took them out and put in the 764's. two steps colder are autolite 94's which would be equal to your AWSF-12C.
my 103's did not foul at all - but the car was retarding timing knock sensor i guess.
bottom line is I want what plug is going to work right with my tune, and that I was told was the 764's and change them often. so far so good, the only thing i did notice with the 764's, after wot runs i get a bit of a sulfer smell... where with the 103's i could beat run wot pulls all day and never smelled the rich sulfer smell - so i guess more fuel was being burned??? this is just my experience.
I was all gung ho about "colder plugs" for the nitrous im going to run very soon. Gene says that with his tune and the 764's I can comfortable my 100 - 150 shot with the 764's. (im assuming he is taking account for an adjustable fpr and walboro 255.
regardless im going to dyno tune this, and i have both sets right now... 103 and 764, and wouldn't mind buying the 94's if need be. I also am on the fence for wires, taylor livewire and nology are tempting, FFRP will probably be enough wire for what I have planned hp wise though, I see the cobra guys making huge numbers with those exact same FFRP wires.
so yea your argument about running colder until fouling is well based and valid. My argument is that those awsf plugs have to be bought online through someone who has them on the shelf. There is nothing wrong with autolite... I don't see why you don't run an autolite plug in the colder heat range, there should be no difference between them and your motorcraft awsf 12c and autolite 94's - both two steps colder. the 103's are one step colder than stock, so them and the motorcraft awsfa-22c shoudl act exactly the same, i ran 103's and they didnt cooperate with my tune.
what year make and model took the awsf 12c and 22c btw?
