View Full Version : Denzo Iridium Plugs ?

09-12-2004, 02:42 PM
I seen one person (Mark Kovalcik) on this board with these and they are in the 12's with nice Hp + tq #'s running these plugs.. anyone else running these plugs in there SC ? i bought these for my civic and i like them, but if i can buy them for my SC i want to.. i went to there website and got this below, not listing for the SC's can i use another one ? a V8 listed one ? Alex L

Iriduim # (ITF16 for V8's only ????)

1991 FORD THUNDERBIRD______5.0 L - V8___ ITF16____0.054
1991 FORD THUNDERBIRD LX____3.8 L - V6___??????____0.054
1991 FORD THUNDERBIRD LX____5.0 L - V8___ITF16_____0.054
1991 FORD THUNDERBIRD SC____3.8L - V6___??????_____0.054

09-12-2004, 03:46 PM
NGK makes iridium plugs for the SC. I'm not sure that anyone else does. I don't have the part #'s handy right now, but I can dig them up if someone else doesn't chime in. I had them in my '89 and am satisfied greatly with them. Once I need a tune up on my '92 the iridiums are going in it as well.

09-12-2004, 04:22 PM
my mistake, he has Iridium plugs listed, i assumed only Denzo made them.. ok i'll call autozone then they should have them... thanks Alex L

09-12-2004, 04:27 PM
i just called autozone and no #'s listed for my car ? 1991 T-bird SC ? if someone has the part # handy i'd appreciate it.. thanks Alex L

09-12-2004, 04:48 PM
i found the info on NGKsparkplugs.com easy to look up i did a chart like theres, here it is below.. i'm calling autozone now to see if they habve the NGK p/N i have listed, because in there computer they dont have anything listed. will repost and let you guys now if autozone has them under the part #'s i have Alex L

09-12-2004, 04:55 PM
of coarse autozone doesnt have them..now i gotta find where to get them..Alex L

09-12-2004, 04:59 PM
summit does, NGK-7316 SPARK PLUG (should ship by Tomorrow) $6.99 not to bad, i paid 12.99 each for my denzo iridium plugs for my honda.. Alex L

09-12-2004, 05:53 PM
Denso does make an Iridium plug for the SC, I believe the IT20 is stock plug and the IT22 is colder (maybe too cold!).


The NKGs are probably half the price of the Densos.

09-12-2004, 06:04 PM
Thanks "gldiii"
but what are a better choice ?

IT20's (5326) ? or the colder IT22's (5327)? and why ? Thanks Alex L

09-12-2004, 06:38 PM
I haven't used either plug so I cannot tell you from my experience. XR7 Dave reported the "22"s were a little too cold and would foul in his car, so it would appear the 20s would be the better choice. But, of course it all depends on your application!

There are pages of threads on the Iridium plugs with info from people that have actually used them. Just search on "iridium" or "denso" and you'll find hours of reading material.

Once you have searched and read the info, I'm sure you'll have a list of posters to contact with additional questions.

09-12-2004, 08:09 PM
Use IT20's They are grear..And actually a tad colder then stock if I recall

09-12-2004, 09:24 PM
I have tried the denso plugs and did not like them I had a lot of problems with them. I have switched to the lighting sparkplugs which are 2 heat ranges colder that a stock NA spark pulg. The lighting plugs are fully threaded. The lighting plugs are a iridium plug. I have been told the lightning plugs will fit any 3.8 or 4.6. The lightning part number is AGSF12-FM1. If your prefer to run coppers you can use partily threaded AWSFA 12 C or a fully threaded AGSF12C PLUG.

09-12-2004, 09:34 PM
I ran the ngk irigiums, p/n ngk tr55-ix or something like that. Bought them off of ebay for $40 shipped for all 6. The sellers store was called sparkplugsource. Highly recommended, excellent plugs.

09-13-2004, 12:41 AM
I didn't know that Lightenings came with Factory Iridium Motorcraft plugs?

09-14-2004, 09:50 AM
Use IT20's They are grear..And actually a tad colder then stock if I recall
Damon.......I have I's in both my XR7 and SC. I installed them right out of the box which is .055 gap. Do you gap yours less? If so, why?

Ed Springer

90 Black XR7 5-speed: 70mm TB, Fresh Air Intake, '94 Supercharger, 5% SC Pulley, Raised SC Top, I/C Fan, Under-drive Pulleys, 190 l/h Fuel Pump, 36# Injectors, Headers, Magnaflow Muffler (no cats) with stock resonators, 3:27 Gears, Ripper Shifter, 73mm CL MAF (Blue Tube), Magnacore Wires, NGK Iridium Plugs and Rear Spring Air Bags.

94 Red SC Auto: 70mm TB, Fresh Air Intake, Stock 90 SC Pulley, Raised SC Top, I/C Fan, Under-drive Pulleys, 190 l/h Fuel Pump, 38# Injectors, Headers, Raven Muffler (no cats) with stock resonators, 3:73 Gears, 76mm CL MAF (Gold Tube), Magnacore Wires, NGK Iridium Plugs, TRANSGO Shift Kit, Pro-Torque 2500 Stall TC, Haydon Auxiliary Transmission Cooler, Tokico Struts & Shocks, American Racing 17 Sniper Wheels, Michelin Pilot Sport A/S Tires and 235 RWHP with 315 LB-FT Torque.

09-14-2004, 04:44 PM
i ordered my plugs yesterday (denso iridium [email protected] autozone) they should be comming in today threw fedex at the autozone, now do i need to regap these ? plz get to me asap ppl ? i want to install them but not sure if i should ?? Thanks Alex L

09-14-2004, 04:48 PM
I didnt regap mine and had no spark blowout at over 17psi(Dave disclaimer because I dont want to hear it)

Remeber youll make more power with a wider gap so long as you dont blow out the spark:O)

09-14-2004, 04:55 PM
so whats the best choice ? leave it alone? or gap it to ? what ?? thanks Alex L

09-15-2004, 07:38 AM
I didnt regap mine and had no spark blowout at over 17psi(Dave disclaimer because I dont want to hear it)

Remeber youll make more power with a wider gap so long as you dont blow out the spark:O)

Thanks for the info. I have not had any blow out problem with iridiums. I pulled one the other day out of my 94 just to see how it was burning. It looked great.

09-15-2004, 10:46 PM
Alex, they should come pre-gapped. I threw mine right in with no problems. Didn't even bother to check the gap now that I think of it. :eek:

09-16-2004, 06:56 PM
The gap is slightly larger then reccomended for an SC....But the Iridium plug gives a stronger spark by nature..Theoretically you should even make a tad bit more power

09-17-2004, 08:42 PM
Thanks "blown96bird" "MannySC"

i ordered my dam denso iriduim plugs on tuesday(said i could get them for next day and i was happy, because i needed them for sat but needed them before to put them in so i could go to the track), and i got told they'll be in wed, then wed comes, they said they contacted denso and they didnt ship it for some reason, then thursday comes now i'm mad, they said they didnt know why but it should of been there, i contacted district manager and tell him i am mad, he was cool try'n to find them locally and buy them outright for me on thursday, and couldnt find anyone that was a dealer or had any in stock. so i just said screw it i'll wait untill tomorrow again like he said they would come in, i didnt want to get them on friday (today) and put them in and race tomorrow i wanted to have some extra time, so i wait untill today, call at 12 pm they say call back at 3:30 and thats the last fedex truck ? i was like ok, so i call at 4ish, and guess what, no dam plugs i get the "they will be in tomorrow morning" i was like ~~~ ? (we contact the denso company again and talked to someone corparate blah blah blah, i can have them shipped next day special shipped ) i say i'm goin to the track in the morning i cant do that.. now i was pissed, but then remembered that "blown96bird" mentioned about stock lightning plugs are iriduim, so i call the stealership and get them there just had to drive about 20 mins and got my money back from autozone... thats just my luck (could of been a little worse and me not able to get the lightning ones, but).. i'm happy now my car feels better seems to idle better also, my dad looked at my plugs and said dam, they dont look to good he said how long were they in there i said a few yrs, but not many miles on them at all.. but it was due!! then i didnt know what to gap this kind of plug at ? so i msged MannySc and he recomended gapp'n them at .40 so i did (had to get a fealer gauge) now i'm ready for the track in the morning so thanks again guys at SCCOA :) Alex L

09-17-2004, 11:20 PM
Ford Lightening Plugs are DEFINATELY Iridium plugs? Motorcraft makes them?

What do they run, and are they as good as the Densos or NGK plugs?

09-17-2004, 11:24 PM
i imagine so, lightnings arent cheap, they look just like my denso iriduim's i bought for my civic.and someone else said so, so i imagine there correct. they were about 55 or 56 bucks for all 6.. Alex L

09-18-2004, 11:19 PM
Just like I read in another post, Perhaps a manufacturer is contracted out and the motorcraft name is put on them. We've all known for a long time that Autolite plugs are sold as Motorcraft through Ford dealers, so perhaps Denso is the supplier for these....

Anyone know for sure? Got pics?

09-19-2004, 03:03 PM
Does anyone have the part number for the Lightening plugs. I have a 93SC and dont know what year to ask for. The plugs and wires are the last thing needed.

09-19-2004, 06:48 PM
"blown96bird" already posted in this post about the part # :) here it is..

The lightning part number is AGSF12-FM1

09-19-2004, 09:12 PM
I'd look at those Lightning plugs a little more closely and compare to your stock plugs that you have pulled out.


If they are like this picture shows they may have threads that will extend into the combustion chamber which could cause you problems as combustion residues build up on the thread and then you try and screw them back out of an aluminum head!

The unthread part on the stock SC plug sticks in the cylinder, but it is a smaller diameter than the threaded part. Plugs like the APP103 are shorter and do not extend into the cylinder.


Some plugs may have more threads on the barrel of the plug up towards the seat, but you do not want the distance from the seat to the end of the threads to be any longer than stock.

More plug info here:



09-19-2004, 09:29 PM
"gldiii" my plugs didnt look like that (before i put them in), i dont remember about the threads and all that but i remember that the center didnt look like that. it was a very skinny middle piece like my iriduim plugs from denso (for my civic). i dont think those are iriduim plugs, the color was not that color as i said they seemed to like exactly like my denso ones they were a platinum silverish look. Alex L

09-19-2004, 09:41 PM
Alex, my reply has nothing to do with plug color, tip or electrode size. It is all about the thread depth on the plugs. This was also addressed specifically to the Lightning plug application.

The plugs you have may be fine, but it is an easy check for others to do before they install a plug that could damage the threads in the aluminum head when they try to remove them many miles later.

09-19-2004, 09:55 PM
trying to find a pic or more info, but got this so far from


AGSF12FM1f4 $8.41 $6.90
Electrical - Ignition system - Spark plug - 5.4 liter
W/supercharger 1999 - 2003

09-19-2004, 10:08 PM
wow rockauto.com has them for under a 99 ford lightning for 2.57 each, i paid 8.41 each from the dealer.... dam..

09-19-2004, 10:21 PM
after try'n to search for pics i couldnt get one on that part # but i seen alot of lightning post places and where ppl talk about the lightning there all almost using denso iriduims... i wonder if now i should change ? dam.. 53 bucks maybe lost.. :(

09-19-2004, 10:46 PM
"gldiii" i missed your re-post.. u think it will really damage the heads later on ? that sucks, now i find this out after i pay 54$ bucks and install them :( but i guess thanx for lett'n me know... well for anyone else that reads this like i posted previously i seen alot of lightning people use denso iriduim plugs.. so i wouldnt do the mistake that i did and get these then, especially if they can harm your head later.. i wish i would of known this before.. :(

09-20-2004, 02:10 AM
after try'n to search for pics i couldnt get one on that part # but i seen alot of lightning post places and where ppl talk about the lightning there all almost using denso iriduims... i wonder if now i should change ? dam.. 53 bucks maybe lost.. :(

What did you put in?..Almost any new plug should be fine..I just perfer denso IT20's

Not worth rechanging if you put new ones in already