Here is some more confusion for ya....Not that sparkplugs.com knows what they are talking about but this is what they recently told me...
Hi Jeff,

both the tr6 and the it22 convert over to the autolite ar103

thank you,
natasha
sparkplugs.com

 

I'm running 14-16psi (depending on ambient temps) and have no issues with IT-20s gapped at 0.032"

The color looks correct, Does this sound like the correct plug I should be using?

Rich

 

Just installed the TR6IX gapped at .038"

Removed IT-22s due to gap creap. The TR6IXs idle excellent and throttle response may be a little better, but basically they appear to be similiar.

 

Updated chart with data I found on NLOC

 

Ditto. Runnin' great. 5# lower and ported blower.

 

Good info...thanks! Looks like the TR6 is one range colder than the FM1's after all

 

I don't know if this info is correct YET, all I am doing right now is finding data on sparkplug threads then comparing what everyone has posted. Seems, alot of people are getting different information.

Your input is still needed

 

When I got the blower ported my tuner said to get the gap down to 0.032" I had them at 0.040" and did notice a little flutter at about 4000 rpms as compared to now. I guess it was on the verge of blowing the spark out... or something?

Rich

 

Hmm my TR6's are gapped at 0.040 right now w/ 4# and ported blower. Maybe I should drop them a little before WFC

 

I have been told that our ignition system is fairly weak when compared with the single coil aftermarket systems like for the old 4.6's and 5.0's. Our coil packs tend to degrade after a year or two. Hence why we have to run a tight plug gap (e.g. 0.035") to keep the spark from blowing out.

 

Ya I have my IT-22s gapped at .040 also with a 4# and ported blower.

 

.035 gap is standard practice for any nitrous or forced induction car regardless of ignition system from what I have seen.

Although you may be correct about the coil packs degrading, that is probably not the main reason for tight gaps. It wouldn't surprise me that they are a "wear" item, they live in a tough environment.

TR6 seems hotter than stock according to that chart. The 12FM1 motorcraft plugs are in the wrong place, 12 indicates the heat range, 12 copper and 12 iridum are in the same heatrange. Seems like the fm1's need to move over to the right a a few boxes.

Also, I was right about stock plugs being iridum. nanny nanny boo boo

 

Antoher thought:

Probably the best bet is to simply use the copper version of the stock plugs, the 12c's. Copper will pull more heat out of the cylinder unlike platinum/iridium, and you are still using OEM parts to stave off anyworries with something like a blown sparkplug or anything else they might try to blame on it.

 

Are the 12MF1's stock plugs for the L or not?
If it is a stock plug like you say, why would it be colder to handle the same boost levels?

 

12FM1's are stock. They are much colder than most people think.

They are in the same heat range as 12C's (motorcraft copper) and slot right between NGK tr6 and NGK br7ef plugs.