Spark plug gap

[Ecky]

Can someone educate me on how to adjust spark plug gap when changing electrode type?

Vehicle in question is a 92 Civic with one of Honda's lean burn engines, and it's rather sensitive to changes in ignition. Stock plugs are NGK coppers gapped at 0.032". Hypothetically, if I changed them out for iridium or platinum plugs, how would the gap need to change? This engine is old enough to have still been using a distributor, so I imagine the specs from a newer variant that calls for iridium plugs and uses COP would not be appropriate.

 

[Lubener]

Some plugs are pregapped but can be gently rechecked. I have always stuck with the factory gap specs regardless of the plug type I used, be it copper, platinum or iridiums.

 

[DGXR]

I would use the specified gap of 0.032" and see how she runs. Generally the harder metals don't conduct as well as copper, so it's possible the gap may need to be tighter but probably not much... if it doesn't run well on iridium/platinum plugs with the stock gap of 0.032", I would try 0.030"
Plug gaps get larger with mileage.

 

[zrxkawboy]

Some ignition systems designed for standard plugs don't run as well with platinum/iridium. I don't know if that applies to Hondas, but I've seen it in other makes.

 

[dubber09]

Go to NGK website and check what plugs they have listed for your car, buy what you like from that list.
As far as Plat plugs - VWs for example didn't like them much back in the day.
As far as gap - if it's too wide you may have misfires and if too small then you may not burn all fuel causing soot buildup and fouling cat.

 

[NitroM3]

Go to NGK website and check what plugs they have listed for your car, buy what you like from that list.
As far as Plat plugs - VWs for example didn't like them much back in the day.
As far as gap - if it's too wide you may have misfires and if too small then you may not burn all fuel causing soot buildup and fouling cat.

You remember.

German manufactured engine in general

When the BOSCH Platinum's first came out I was given a few sets to try out in my various vehicles. The only one I installed them in was my 911.
The first time I drove as I normally did back then I thought I had done something to the engine. It fel flat on its face. After doing several checks and could not find a problem because if I drove it like a station wagon with grandma as a passenger it was fine, nail it and back to digging for the my AAA card incase I need a tow home. When I finally put my Porsche up on my oscilloscope and there it was plain as day. The wave pattern was terrible . OUT came the bosch platinum's and back none platinum spark plugs and having fun again in my frog!

pretty much agree with your gapping suggestion!

 

[slacktide_bitog]

Page 116-117 of the owner's manual seems to suggest .044 in/1.1mm
VX is the lean-burn model, engine code D15Z1

The main difference is that the VX calls for one heat range hotter then otherwise.

The NGK website also confirms .044 in/1.1mm gap. The factory plugs seem to be NGK V-Powers

Anyway, gap should be the same even with platinum or iridium. I've had distributors, COP, waste spark, etc, that called for similar gaps.

The good news is that changing them is easy on your car, and they don't cost much, so you're free to experiement

 

[dubber09]

You remember.

German manufactured engine in general

When the BOSCH Platinum's first came out I was given a few sets to try out in my various vehicles. The only one I installed them in was my 911.
The first time I drove as I normally did back then I thought I had done something to the engine. It fel flat on its face. After doing several checks and could not find a problem because if I drove it like a station wagon with grandma as a passenger it was fine, nail it and back to digging for the my AAA card incase I need a tow home. When I finally put my Porsche up on my oscilloscope and there it was plain as day. The wave pattern was terrible . OUT came the bosch platinum's and back none platinum spark plugs and having fun again in my frog!

pretty much agree with your gapping suggestion!

Good plugs for VAG were Silbers ... I do remember

 

[Ecky]

It's certainly easy and cheap enough to just try/experiment, so perhaps I'll do just that. I know anecdotally, people have told me these engines simply do not run right on non-copper plugs. Honda started using non-copper plugs for the first time in an extremely lean burn engine at the same time as moving to the much stronger coil-on-plug ignition, and it wouldn't surprise me if there's a connection - if the older distributors just didn't have a powerful enough spark with less conductive metals. Even as late as 2000 the same copper plugs were being used in their lean burn engines, while iridium plugs were an option for all of the others.

Good tip on the NGK website - I didn't think to check if they had a part finger. Unfortunately, they only list OE copper for that engine.

I guess what I mean to ask though, is, in engines that do not run as well with platinum or iridium plugs, why? And what adjustment can be made (if any) to correct it?

 

[slacktide_bitog]

It's certainly easy and cheap enough to just try/experiment, so perhaps I'll do just that. I know anecdotally, people have told me these engines simply do not run right on non-copper plugs. Honda started using non-copper plugs for the first time in an extremely lean burn engine at the same time as moving to the much stronger coil-on-plug ignition, and it wouldn't surprise me if there's a connection - if the older distributors just didn't have a powerful enough spark with less conductive metals.

Good tip on the NGK website - I didn't think to check if they had a part finger. Unfortunately, they only list OE copper for that engine.

I guess what I mean to ask though, is, in engines that do not run as well with platinum or iridium plugs, why? And what adjustment can be made (if any) to correct it?

Iridium and platinum plugs have thinner tips and actually require less effort from the distributor/coil/etc, lower voltage--not more.

I never had any problems using platinum or iridium where OE was copper, but the only Honda I did spark plugs on was a newer Civic that has COP and OE iridium.

As far as your engine goes vs what other Civics came with, it's just the heat range. Maybe the colder plugs foul more on the lean-burn engine. The only difference between VX plugs and the ones used on other Civics is the heat range, and those other Civics with the colder heat range have platinum and iridium available. In NGK's numbering system, a higher number means colder heat range. The VX heat range is 4, whereas others use a 5.

If you drive flat-out on the highway a lot, the colder plugs will be no problem. If it's mostly city driving you do, then they could foul.

 

[UG_Passat]

You remember.

German manufactured engine in general

When the BOSCH Platinum's first came out I was given a few sets to try out in my various vehicles. The only one I installed them in was my 911.
The first time I drove as I normally did back then I thought I had done something to the engine. It fel flat on its face. After doing several checks and could not find a problem because if I drove it like a station wagon with grandma as a passenger it was fine, nail it and back to digging for the my AAA card incase I need a tow home. When I finally put my Porsche up on my oscilloscope and there it was plain as day. The wave pattern was terrible . OUT came the bosch platinum's and back none platinum spark plugs and having fun again in my frog!

pretty much agree with your gapping suggestion!

Back in the day, Bosch used to brag about the amount of platinum in their platinum plugs as their entire center electrode was platinum.

Times have changed, now it's the nickel core with the platinum, iridum, or ruthenium tips, and VW has used Bosch platinums, then NGK platinums for a while.

 

[GMBoy]

Those plugs are so easy and quick to change why not just run the recommended regular copper plug and change every 30-40k miles? If you truly want to upgrade to longer life plug just go up 1 step to a single platinum plug which is mostly just a copper plug with a platinum puck attached to the electrode. This basic plug acts more like a copper but has longer life with the small amount of platinum on the tip so you can expect 60-80k miles on average. A good choice would be a basic Autolite Platinum plug at like $1.50 a plug on rockauto but there are plenty of other choices as well. I am betting a Denso Platinum TT plug would work nice on your Civic.

 

[NitroM3]

Can someone educate me on how to adjust spark plug gap when changing electrode type?

Vehicle in question is a 92 Civic with one of Honda's lean burn engines, and it's rather sensitive to changes in ignition. Stock plugs are NGK coppers gapped at 0.032". Hypothetically, if I changed them out for iridium or platinum plugs, how would the gap need to change? This engine is old enough to have still been using a distributor, so I imagine the specs from a newer variant that calls for iridium plugs and uses COP would not be appropriate.

Ok so I realized that I failed to give a recommendation:

Because of the year and not knowing anything about your engines health ,mileage oil consumption, condition and age of the other ignition components etc. and because your are asking how to gap a spark plug this is what I would do to help you,
Buy a spark plug that is boxed "PRE GAPPED" and stay with a brand that you are familiar with or look into a service guide ,factory service manual or what a spark plug supplier show that is applicated for your year and engine size.
Many spark plug types can easily be damaged by incorrectly gapping them. And most people incorrectly gap spark plugs the proper way and always assume that the gap measurement is all that is in the procedure which it is not.
I highly recomend that you stay with exactly with a spark plug heat range that is shown to be for your application.

Changing a heat range on a daily driver engine (or even a performance run engine) is very involved and this is also an area that many get wrong on how to determine and test to use different heat range spark plug then a factory recommendation.
On a race engine choosing a proper heat range plug is determined by trial and era. There are base lines to start but it is not simply going a step hotter or colder and during all this most have a large array of monitoring gauges if a computer control engine access to the Diagnostic connector but in most cases you still need an Air/fuel Ration gauge. So race/performance engine because of the monitoring that is done generally those people are already familiar with how to choose and gap a spark plug correctly and find a heat range that will be safe and work for the intend use of the engine. On a street car or stock engine daily drive there is a tremendous difference in the engine environment and running conditions, its virtually impossible to choose different heat range spark plug that will work to support the engine. Changing heat range on a street car are often used as a band-aide for more serious problems problems. Unknowingly to by many when they use different heat range plugs they contribute to more engine problems. So unless a trained professional suggest that a different heat range be used based on a physically assessment of your engines and ignition systems health it not something just anyone should do.

 

[AutoMechanic]

I’ve seen many where they won’t run right on different plugs. I’d keep the copper. I don’t think the gap would matter on a different plug because it’s going to tell it’s different either way most likely. Also don’t forget the anti seize on them. Believe me I’ve dealt with too many seized and stripped plugs to not use it no matter what the manufacturer says. Remember they aren’t the ones changing the plugs.

 

[mk378]

If you acquired it used, check that your car hasn't been Frankensteined with non-VX engine parts. That will never run right.

The VX engine uses a wideband O2 sensor to achieve lean burn. It is kind of common for the sensor to be worn out of spec and cause runnability problems, but not throw a code.

Baseline "is it running right" test would be a new set of copper plugs properly gapped. Brand new copper plugs will work as well as anything else. The issue is what happens as they get old.

The ignition is rather powerful for a distributor system but it depends on the spark wires being good. You can't tell if wires are bad by visual or ohm tests.

 

[PandaBear]

Gap has meaning when you involve surface area (tip diameter). When you go from steel (aka copper) to platinum and iridium with fine tip you do not need that gap, a much wider gap would work just fine. So you do not NEED to adjust it to that, also you may crack the hard precious metal tip if you try to adjust it. I'd just leave it alone.

 

[Ecky]

I’ve seen many where they won’t run right on different plugs. I’d keep the copper. I don’t think the gap would matter on a different plug because it’s going to tell it’s different either way most likely. Also don’t forget the anti seize on them. Believe me I’ve dealt with too many seized and stripped plugs to not use it no matter what the manufacturer says. Remember they aren’t the ones changing the plugs.

I've personally seen more stripped threads due to over-torque. I've read variously that torque needs to be reduced ~40% when anti-seize is used, to get the same clamping force, but with that reduced torque the plugs in my Insight kept backing out, and I wasn't comfortable with torqueing them to spec with anti-seize because the threads are easy to strip.

If you acquired it used, check that your car hasn't been Frankensteined with non-VX engine parts. That will never run right.

The VX engine uses a wideband O2 sensor to achieve lean burn. It is kind of common for the sensor to be worn out of spec and cause runnability problems, but not throw a code.

Baseline "is it running right" test would be a new set of copper plugs properly gapped. Brand new copper plugs will work as well as anything else. The issue is what happens as they get old.

The ignition is rather powerful for a distributor system but it depends on the spark wires being good. You can't tell if wires are bad by visual or ohm tests.

The car in question is actually the infamous Aerocivic, which I acquired from its original owner a few months ago. I'm working on restoring it mechanically.

The car started as a CX, but had a VX swap. The engine is a JDM equivalent to the US VX engine, and it has a European VX equivalent ECU which is supposed to have a wider lean burn window (and maybe runs more lean?). The car runs great, with no CEL, but it's clearly due for a lot of regularly maintenance.

I appreciate all of the info! I'll get a baseline with some new OEM copper plugs, and then try some iridium or platinum plugs with the same heat range and gap, and see how it does.