Iridium Spark Plug Gap For Non-Boosted 1FZ? (1 Viewer)

[Tachycardic]

I plan to install Denso Iridium spark plugs (part# IK16 - 5303). They have a factory gap of 0.4mm.

The OEM copper plugs have a gap of 0.8mm.

I read that there is no need to regap the iridium plugs. Is this true? TIA.

 

[devo]

Why did you decide to use this plug, are there benefits over a conventional plug?

 

[smritte]

Don't try and gap iridium's. odds are you will break it.

are there benefits over a conventional plug?

The biggest benefit is longevity. Thermal and electrical properties are close to copper. With copper, you pulled the plug out periodically, cleaned, filed and regapped it. When smog regulations came around, we were forced to develop a plug that lasted the new required time frame (50k miles). The first plug to be developed was platinum. The issue there was, the properties were not as good as copper and they didn't like higher compression but, they went the required 50k miles for the most part. At the shop, we only had failures with the higher compression engines if the customer ran cheap fuel. This led to Iridium's. The properties were very good and they can go 100k in most vehicles. The down side though is they can build a carbon like ring around the bottom over time. This can cause issues when trying to remove them (ford truck heads). The solution is to just remove them about every 50k to insure the threads are clean. Some vehicles are worse than others for this. I have never seen any carbon build up on my cruiser plug but, I still pull and check them every now and then.

 

[devo]

Interesting, thanks. Are they in the same heat range as the OEM spec?

 

[smritte]

"If" you buy the Denso, yes.

Some years ago I attended a spark plug seminar (yes I'm a nerd). One of the things they spoke about is the inconsistency in spark plug heat ranges. Each plug manufacture has their own scale and they tend to not be the same. Here's an over simplified example with somewhat fictitious numbers.

Lets say heat ranges were numbered 1-10 with 1 being coldest and 10 being hottest. The vehicle manufacture will designate the proper heat range using their own scale.
Lets say our Cruisers were a #7 using Denso plugs. You go to the auto part store and buy a Champion #7. Because Champion uses a diffrent scale it could be #10 by Denso standard. Now its too hot.

Most of the time the heat ranges are close enough that you never notice the difference. This exact scenario happened to one of my friends. He pulled out the proper plugs and installed Champions. He didn't notice a difference until he went to smog the truck. He gross polluted with NOX due to the now high cylinder temp. We installed the proper plugs and all was good again.

I'm not saying you "need" to run Denso but, if you don't there is a chance the vehicle wont run correctly.

 

[Kernal]

For my stock NA 96 FZJ80 I had been running Denso Iridium Power plugs (# IK16) with an Iridium center electrode for almost 20 years (two sets ~100,000 miles each), never touched the gap. Just visually inspected the gap and electrodes to ensure they hadn't been damaged prior to installation.

Recently (20,000 miles ago) I installed Denso Iridium TT plugs (# IK16TT) into my NA 97 model. The Iridium TT plugs have an Iridium center electrode and a short platinum post on the side electrode.

Main advantage IME to either Denso Iridium plug is that the plugs last longer than standard plugs and the engines seem to run a tad smoother, maybe even with 0.1% more power

FWIW

 

[devo]

This all interesting info. It’s pretty easy to go down the spark plug rabbit hole.

 

[smritte]

Welcome to my world