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Denso Iridium TT Spark Plug Gap #4559779
10/31/17 12:33 AM
10/31/17 12:33 AM
Joined: May 2009
Posts: 2,304
WA (USA)
Y_K Offline OP
Y_K  Offline OP
Joined: May 2009
Posts: 2,304
WA (USA)
I am trying the Denso IT16TT (4713) on my Towncar and it works fine. Panthers traditionally require 0.54 inch gap (1.4 mm). The Denso plugs come in at 0.40 preset from the factory, and I have verified that. I am confused after all the reading I have done as to whether I need to re-gap those or just leave them be. Hence, my request for the collective wisdom, based on practical experience. Similar Denso plugs look like new after 120k miles on my Landcruiser, That is why I decided to try them on a panther.


"This forum talking about 4wd systems is like when other forums talk about oil."
Re: Denso Iridium TT Spark Plug Gap [Re: Y_K] #4559787
10/31/17 01:25 AM
10/31/17 01:25 AM
Joined: May 2013
Posts: 2,160
Saskatchewan, Canada
Johnny2Bad Offline
Johnny2Bad  Offline
Joined: May 2013
Posts: 2,160
Saskatchewan, Canada
Iridium is a very hard, brittle material. Re-gapping (you should check, though) is not recommended as you may create cracks or actual breakage, now or sometime after installation.

0.54 is a fairly large gap for a modern OEM recommendation, but it's not out of the realm of practicality ... an electronic ignition in good condition should be able to cross about 0.60 with typical street vehicle compression ratios and maximum RPMs. On the other hand 0.40 is not "too close" ... the plugs will work fine with that gap, again with any modern electronic ignition.

There are advantages to having as wide a gap as possible, but then again there is a line where you start to get misfires. Unless you have a highly tuned high compression race motor, the added value of that extra 0.14" isn't critical (it un-shrouds the spark a little, which in theory makes it easier to light the charge, but if you're not misfiring, which you should notice as roughness, it's lighting the charge just fine).

Use the pre-gapped plugs and stop worrying. Your car will probably be just fine with it.

If you happen to be running a points-style mechanical ignition ... rare, these days; even Big 3 motors have had electronic ignition since the 1970s as standard ... then maybe 0.32 might be more to the engine's liking. Or the other option is magneto ignition, again rare unless a purpose-built race engine, likes a big gap but will misfire at lower RPMs, where the engine's purpose isn't relevant (such as drag racing) or it's done for style reasons (hot rods, custom big motor / super-lightweight motorcycles). Neither is likely to apply to you, or anyone for that matter who doesn't know exactly which gap they want to run.


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Re: Denso Iridium TT Spark Plug Gap [Re: Y_K] #4559809
10/31/17 03:57 AM
10/31/17 03:57 AM
Joined: Oct 2005
Posts: 11,408
PA
d00df00d Offline
d00df00d  Offline
Joined: Oct 2005
Posts: 11,408
PA
Is the ground electrode iridium? I thought it was only the center electrode. The ground electrode should be able to be bent slightly without cracking or breaking.


2008 BMW M3
Re: Denso Iridium TT Spark Plug Gap [Re: Y_K] #4559929
10/31/17 07:16 AM
10/31/17 07:16 AM
Joined: Jun 2003
Posts: 5,949
Illinois
SHOZ Offline
SHOZ  Offline
Joined: Jun 2003
Posts: 5,949
Illinois
The Denso TT Iridium have a platinum pos pad with a copper core and iridium neg pad on a steel strap. I use then in my Gen Coupe and have to close the gap from the pre gapped .043" to around .030". Use a needle nose or tool designed to bend the ground strap to spread the gap. Just tap them on a hard surface to close the gap.


2008 Hyundai Accent 1.6L 5 sp manual hatchback
2010 Hyundai Genesis Coupe Track 2L Turbo 6sp manual
Re: Denso Iridium TT Spark Plug Gap [Re: d00df00d] #4559930
10/31/17 07:16 AM
10/31/17 07:16 AM
Joined: May 2008
Posts: 2,090
SoCal
UG_Passat Offline
UG_Passat  Offline
Joined: May 2008
Posts: 2,090
SoCal
Originally Posted By: d00df00d
Is the ground electrode iridium? I thought it was only the center electrode. The ground electrode should be able to be bent slightly without cracking or breaking.


TT's are twin tip, so it's iridium on both the center and ground.

Yes, having the right tool for the job helps prevent damage to the plugs, so it's the feeler gages with the slotted arm to bend the ground electrode.


2016 VW Tiguan|APR Stage 1|Neuspeed P-Flo|Osram CBI|Redline 5w30
Re: Denso Iridium TT Spark Plug Gap [Re: Y_K] #4559945
10/31/17 07:35 AM
10/31/17 07:35 AM
Joined: Jun 2003
Posts: 5,949
Illinois
SHOZ Offline
SHOZ  Offline
Joined: Jun 2003
Posts: 5,949
Illinois
Actually it's Iridium on the center pad and platinum on the ground pad. The Denso IT16TT (4713) is what I use on my Accent too. Gen Coupe came from the factory with the TTs, Denso 3459 FK20HQR8 Iridium Long Life Plug.

Denso 4701 IK16TT Iridium TT Spark Plug

Denso 3459 FK20HQR8 Iridium Long Life Plug


2008 Hyundai Accent 1.6L 5 sp manual hatchback
2010 Hyundai Genesis Coupe Track 2L Turbo 6sp manual
Re: Denso Iridium TT Spark Plug Gap [Re: Y_K] #4560085
10/31/17 09:44 AM
10/31/17 09:44 AM
Joined: Jun 2012
Posts: 1,757
USA
oldhp Offline
oldhp  Offline
Joined: Jun 2012
Posts: 1,757
USA
It's a street engine......run'em with no worries.


2018 RAM 1500 3.6/8 speed.
2017 Jeep Sahara Unlimited 3.6
"U kan't fixe it......if'n it ain't broke."
Re: Denso Iridium TT Spark Plug Gap [Re: Y_K] #4560152
10/31/17 10:49 AM
10/31/17 10:49 AM
Joined: Jan 2004
Posts: 4,433
California
nthach Online content
nthach  Online Content
Joined: Jan 2004
Posts: 4,433
California
Denso doesn't specify gapping on these - with that said, I gapped a set of Platinum TTs to .033"/.8mm per OEM spec. If you're dropping them into a modern Toyota/Honda or anything that calls for a .044"/1.1mm gap I think you should be fine out of the box.

Re: Denso Iridium TT Spark Plug Gap [Re: Y_K] #4560190
10/31/17 11:20 AM
10/31/17 11:20 AM
Joined: Nov 2004
Posts: 7,798
Texas
GMBoy Online content
GMBoy  Online Content
Joined: Nov 2004
Posts: 7,798
Texas
I like the TT line of plugs and have used the Iridium TT and Platinum TT plugs with good results. I usually use Autolite or NGK but started also using Denso plugs last year.

Re: Denso Iridium TT Spark Plug Gap [Re: Y_K] #4560239
10/31/17 12:21 PM
10/31/17 12:21 PM
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Merkava_4 Offline
Merkava_4  Offline
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Originally Posted By: Y_K
Panthers traditionally require 0.54 inch gap (1.4 mm). The Denso plugs come in at 0.40 preset from the factory, and I have verified that.


Are you sure it's not 0.054 and 0.040 inches?


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