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Discussion Starter #1
I know they list a plug for the Insight...Non Indexed ofcourse...

Just wondering how much a difference it might make....
 

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I'd definitely stick with stock plugs for the Insight. The plugs are individually lettered and match the cylinder. Each cylinder might have a different letter and different cars have different letters. Most Honda dealers probably don't know this. Also, the Insight uses Iridium plugs stock because of the large gap and lower voltage requirements to get a spark. Running a standard plug might really upset the Insight, especially in lean burn.
 

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Discussion Starter #4
ok

I know that the plugs are indexed,iridium,etc....

The Champion #7975 are Double Palladium,also good for 100K...and they are $4.49...

I was just checking to see if anyone has actually tried them....

Please correct me if I am wrong,but I think indexing is done soley to locate the shadow of the side electrode to greatest advantage...Is this basically correct?...Anyhow I will check to see where they are placing the side electrode in the valve pattern...being a 4 valve head with a centrally located sparkplug,I am guessing it faces the electrode shadow back at he exhaust valves....

I certainly don't wanna cause any pre-ignition problems,but I really kinda doubt that using the Champs would do anything detrimental at all...just not brave enough to bet my valves on it,I guess...unless someone else has tried it first,with success....
 

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I will purchase a set, compare them to the ones I replaced from my engine, if they're a match, I'll install them and report on any changes, I get very consistent mileage, so I sould be able to see any effects.
 

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I'm working on changing mine now. I have about 190k on the car and this is the first change. Going to change my original brake pads too :)

Anyway, here are the part numbers for the plugs:

12290-PHM-A01 for A plug
12291-PHM-A01 for B plug
12292-PHM-A01 for C plug
12293-PHM-A01 for D plug

a good price of about $14 each.
They are NGK IR plugs ILZFR5A-II

My question is where the heck did they stamp the letter on the engine or plug as to which one to use? I looked at the diagram on this board and even had my mechanic look and take out the old plugs and we can't find it.
If someone has a camera and can take a picture with specific instructions leveled towards me (idiot level) I'd appreciate it. The diagram they show is like, "It is located over there somewhere."

I don't want to put the wrong letter plugs in the car, or does it matter at 190k?

BTW, I called NGK and asked if the letter was on the plugs and they didn't know. I also have a call into Honda. They probably won't know either cause the guy on the phone was talking about four plugs for the car and I had to explain the whole ABCD thing to him....

Thanks!
 

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dice said:
the indexing #'s are stamped on the head, right next to the spark plug, underneath the coils.
I don't mean to get anyone frustrated with me.... but....

On the actual cylinder head?

Could you guide me a little more please. I go the the engine, pop the coils off and then where do I look, to the right, left...? I was not finding it and the mechanic I took it to did not find it.

Pretend you are trying to explain this to a female and tell me every road mark on my way there.

Thanks.
 

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Discussion Starter #9
markings

The plugs themselves have a letter stamped into the end of the plug head itself...where the wire connects.Look at the plug from the top..the end that doesn't screw into the motor...the Letter is on the very end of the round silver end that connects to the primary wire boot....Also on the cylinder head,the marking is located between the little bolt you took out to remove the coil assembly,and the port into which the plug is inserted...REight on the aluminum head between the those 2 holes....most are B's....
 

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plugs

I'm not sure what indexed even means but I looked at my plugs today and the cylinder markings. All are B. (they are in the back of the engine btw) I assumed that the plugs would all face the same way (I thought that was what the indexing was) but they do not at all. None were lined up straight (with B rightside up) One was about 180 degrees off one was 120 degrees off and one about 30 degrees off. Is this right? If I replace the plugs should I still use Bs or does it have something to do with the depth, not the angle?
 

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Discussion Starter #12
Just use the B plugs,in other words

When they are screwed in tight to torque specs,they automatically index correctly.The direction of the letter B on the plug end has nothing to do with the positioning of the electrode..no worries there...
 

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Re: Just use the B plugs,in other words

eastender43 said:
When they are screwed in tight to torque specs,they automatically index correctly.The direction of the letter B on the plug end has nothing to do with the positioning of the electrode..no worries there...
Well, even though they are all B's when torqued correctly 2 have the grounding electrodes on the top/front side of the engine and it seems like that is wrong. The other one is about 30 degrees from being in the back (which seems close enough to me) I might get some indexing washers but can someone confirm where the grounding electrodes are supposed to be? Since they aren't all facing the same way I don't see any reason to get the $18 stock plugs, I'll just get some champions and index them with washers.
 

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Discussion Starter #14
Very interesting

Very interesting..yeah that's what I suspected...I assume you marked the outside of the plug to determine side electrode positioning when installed...Or do you have the head removed?Anyhow,due to variances in combustion chamber designs,etc,etc,plugs may be indexed to any orientation the design engineering team decides is most advantageous...I have theories of my own,but here is a link that talks about indexing..

http://www.advanceautoparts.com/english ... 001sp.html

I certainly agree that they all should be oriented similarly,but there are atleast 4 orientations that might provide better efficiency,and I could only guess at the correct one...Well,I could BS too,but...

Perhaps ..Go with your mechanical intuition on this,and maybe through careful trial and error something specific could be determined....but I doubt it...In a 4 valve head,with a centrally located plug,it is less important ...Looking at the Insight cylinder head drawings just now has me puzzled as to proper orientation..Anyone?

I also ran across this,but drilling holes in ground straps sounds like risky business to me..Anyone willing to try this?A bit off topic,too.Sorry

http://fueleconomytips.com/2005/10/28/spark-plug-magic/
 

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Indexing

After thinking I should go back in and retorque the plugs correctly instead of worrying about what angle they are I took another look at how they were lined up. The first plug that I looked at had the B lined up with the electrode so I guess I assumed they all did and that is how I was determining what angle they were indexed at. The other two plugs didn't have the Bs lined up with the grounding electrode. Honda did do it right, they were indexed correctly and torqued correctly. I ordered some new Bs. I got my 100k miles out of the first set so I'll give another set a try and see if it makes any difference (doubt it.)
 

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Discussion Starter #16
Great..

Hey I wonder if you could tell me how the plugs are oriented...That is,where is the ground strap electrode placed in relation to the exhaust valves?(Exhaust valves are in front ,ie,forward facing part ,of the head.

Infact if you can just tell me where it is in relation to the motor,ie,front or back,that would be helpful...

I am just curious as to the orientation...Thanks,Bob
 

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index orientation

The grounding electrodes are on the bottom/back (plugs are in at about a 45 degree angle from horizontal) so that the gap faces forward. Odd though, I thought that the gaps would point toward the incoming gas/air mixture. Are you sure the exhaust valves are in the front?
 

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Discussion Starter #18
yup

Well the intake manifold is in front,so the flame window is apparently pointing at the intake valves.....my error,not the exhaust valves...sorry for the ineptitude/confusion...

Anyone cocncur?
 

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Or Iridium. ;) Nice work.
 
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