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Just Some Dude in Jersey
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Discussion Starter · #1 · (Edited)
I had read in a thread here that the “best” ultimate spark plugs for our engines was:

NGK Iridium BPR6HIX

And the next best was:

NGK Platinum BP6HVX

So I went to my excellent local auto parts store and they didn’t stock either of them, but they cross-referenced and said that they did have these Denso’s which they said were the equivalent:

Denso Iridium IW20 (5306)(I06) – the last two were other designators on the box.

I have a high energy MSD ignition system and I wanted to increase my plug gap because of this, so why not upgrade the plugs at the same time. They came with .040” gaps which suited me just fine. My previous plugs had less than 5000 miles, but had weathered all my timing, carb, and upgrade adjustments since I’d gotten the car 5 years ago, so a clean slate with the best possible new plugs seemed warranted. My old plugs(which were the correct light brown color, indicating that my air/fuel ratio was in the proper range), gapped at .030-.035”, were:

Champion RL95YC

I put the new plugs in and they work just fine. I’ve only driven a low speed 10 miles with them. I seem to idle a bit faster and run a tad smoother, which seems to indicate that I’m burning gas more efficiently. I noticed that the threaded part of the new plugs was ¼” longer than the Champions and I felt them “push through” some built up deposits, where the previous plugs had reached their insertion limit, while installing them. They performed as advertised so I was happy.

Then that darn Mike Notigan emailed me with concern that plugs that were too long would affect my wave fronts and eventually give me trouble with hot spots from carbon build up and such. Dang him! Dang him to heck! My initial euphoria was popped like a bubble gum blow out all over my face.

I had a spare unrestored 2.0 head in the basement, so I just got done installing both plugs to see what we shall see. Yup, the new plugs stick a whole ¼” into the combustion area. Below are pics.

So my question is: Is this totally unacceptable? I should return them, right? They probably increase my compression a little(Wheeeee!). Should I keep them?

Would the NGK Iridiums listed above have been the proper length?

Please help me out in obtaining the “ultimate plug” for street use in a moderately jacked up 2.0 engine.





 

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The sharp edges on the spark plugs can become a hot spot.
Loose the outer threads or at the very least break the edges.

I'm going to grab the scope this week and snag a few waveforms
that'll show the pressure fronts.
 

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I'm no mechanic but wouldn't the exposed threads get all messed up. When you go to remove the plugs it might bugger up the threads.
 

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Super Moderator
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just posted in the other thread...

Just to wrap up my end of this thread hijack, I got some iridium Denso's that are supposed to be the equivalent of the recommended "best" choice NGK iridiums. They came already consistantly gapped at .040". The previous champions I had ranged in gap from .030" to .035". The threaded part was about 1/4" longer and I feared they might hit the pistons, but the car made it to the show and back, so I guess I'm good t'go!
You should grind the last 1/4" of threads off the plugs then.

Why? Well, in 10,000 miles or so those threads will be so carboned up, you may never be able to remove them from the cylinder head.



 

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Just Some Dude in Jersey
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15,468 Posts
Discussion Starter · #6 ·
I just found a cross-reference chart at this location:

DENSO SPARK PLUGS

It appears that the parts store should have given me IWF20 plugs, instead of IW20's. Those appear to have been spec'd for the Isuzu Opels.

I'm cool with grinding them down and I see that Bob deemed it worthy of his time to grind and polish a "too long" plug to Hubble telescope mirror brightness.

Am I to take it that this is a cool, rad, or otherwise gnarly thing to do?

Did the RallyBob Institute of CIH Overengineering and Endless Research find that doing this improves performance?

The store will probably take them back, shouldn't I just get the proper length plug?
 

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Detroit,where my home was
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2,991 Posts
It appears that the parts store should have given me IWF20 plugs, instead of IW20's. Those appear to have been spec'd for the Isuzu Opels.

The store will probably take them back, shouldn't I just get the proper length plug?
The store SHOULD take them back, it's their fault not yours!
 

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No....its not a Buick....
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1,546 Posts
I never looked at this when I had my 1.5 head off the block........I know the 1.5's combustion chamber is much smaller. I dont remember the plugs being that far in. do I need to bother doing this? I bought the long NGK plugs just for this reason if memory serves. I guess I could always pull a plug out and try it on the "other" 1.5 head and see, but the one on the car is slightly ported and it wouldnt be "exact".
Joe
 

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Well, just to throw another plug on the "pile", here's one that another member found through a NASCAR friend of his. I have used these in my car, but, just for short runs till I could find someone to give me a definitive answer to whether I can leave them in. They clear with no problem in a 1.9 head, I just don't know about the heat range. These are not readily available, and they're not cheap either:shocked:
 

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There are a lot of errors present in the databases of auto part stores when it comes to Opels, even more now than there used to be because of keyword searching.

There is also an error in how a conclusion was reached of how a particular spark plug would perform. It's not unusual that a brand-new part slightly altered might improve performance during its initial drive. You can achieve a bit faster and smoother idle by simply advancing your distributor a few degrees, but that's not a good thing as you would also increase your chances of premature detonation and lose some higher-RPM acceleration when you do that.

The big mistake is not only making a conclusion following a short drive but then "reporting" it here as if that's a universal fact. Shouldn't a more measured or a longer-term evaluation be performed before a thread is started with a title like "Ultimate Opel Spark Plug"? Has a desire for the immediate gratification of participation in social media now eclipsed old-school concepts like disciplined application of a scientific method, particularly when the information advocates other Opel owners to install insufficiently tested parts in their engines?
 

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Just Some Dude in Jersey
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Discussion Starter · #13 ·
I am so raging with anger about so many points made in that last post that my hands are shaking.

Moderators:
Please feel free to rename this thread something less offensive.
 

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Detroit,where my home was
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2,991 Posts
There are a lot of errors present in the databases of auto part stores when it comes to Opels, even more now than there used to be because of keyword searching.

There is also an error in how a conclusion was reached of how a particular spark plug would perform. It's not unusual that a brand-new part slightly altered might improve performance during its initial drive. You can achieve a bit faster and smoother idle by simply advancing your distributor a few degrees, but that's not a good thing as you would also increase your chances of premature detonation and lose some higher-RPM acceleration when you do that.

The big mistake is not only making a conclusion following a short drive but then "reporting" it here as if that's a universal fact. Shouldn't a more measured or a longer-term evaluation be performed before a thread is started with a title like "Ultimate Opel Spark Plug"? Has a desire for the immediate gratification of participation in social media now eclipsed old-school concepts like disciplined application of a scientific method, particularly when the information advocates other Opel owners to install insufficiently tested parts in their engines?
wow---- for a second there I forgot this is a forum where we bounce ideas off each other for trial and error and to further our education on the subject. Looks like self aggrandizement is rearing its ugly head.

How are we to reach the pinnacle of enlightenment without education?

Fun fact of the day....

forum [ˈfɔːrəm]
n pl -rums, -ra [-rə]
1. a meeting or assembly for the open discussion of subjects of public interest
2. a medium for open discussion, such as a magazine
3. a public meeting place for open discussion
4. a court; tribunal


I guess this thread falls under category 4 of sub paragraph b. In the Opel rule book. there are much better ways to show someone the right way than pointing out to everybody his fly is down. This along with refusing to complete orders is a violation of the Opel bro code and not appreciated.

I like goofing stuff up and having to do it over again, if i got everything perfect the first time, it would be boring. Yes wrong spark plugs are a catastrophe, and we should not haphazardly try plugs, but this is certainly the place to get tried and true anecdotal experience from the Opel gods such as RallyBob and Wrench459 etc....

Even with pics in color. Good ole world wide interwebs,,,
:banghead: Now I understand what you're talking about Jambalaya :yup:
 

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No....its not a Buick....
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1,546 Posts
I believe that many of our motors have had some sort of modification in one way or another. Due to the fact of such variances in one motor to another, the ONLY way to test different spark plug brands and such would have to be performed on a BONE STOCK engine to get a starting point and then applied to ones own motor depending on modifications. Sound Good??? Ok... Now... who's got a BONE STOCK motor we can start the testing with??
 

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Just Some Dude in Jersey
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15,468 Posts
Discussion Starter · #18 ·
That's enough discussion about not discussing stuff. :no:

I want to learn something from this thread. :yup:

I'm curious about the concept of using plugs that PROTRUDE into the combustion chamber. I can see potential pros and cons to this. These are entirely layman's guesses and by no means should be taken as definitive conclusions. They are merely points for discussion.

Pros:
Spark occurs closer to the center of the air/fuel column entering the combustion chamber. Possibly less chance of the air/fuel mixture not igniting because the spark normally occurs so close to the wall of the combustion chamber.

Cons:
The plug will get a LOT hotter being surrounded by more flame. Possible interference with the in and out flow of gasses during the cycle. Possible wave front interruption. The risk of a too long plug hitting the piston.

Thoughts on these points and my original questions? :veryhappy
 

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Administrator
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I am so raging with anger about so many points made in that last post that my hands are shaking.

Moderators:
Please feel free to rename this thread something less offensive.
Gordon, as with any internet posting, you have to consider the source before taking it too personaly. We are a diverse group here and as we have seen in the past, not all postings fall within what may be considered amiable.

Dave possesses a wealth of information about Opel's and is a major contributor to the OMC and the Blitz. His style of conveying that information can come across as abrasive and counter to the core spirit of this site.

Speaking for myself, I know Dave's intent is to help and can usually see the point he is trying to get across in the meat of his post.
 

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Sick with Opelitus
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1,374 Posts
Ok... Now... who's got a BONE STOCK motor we can start the testing with??
I do, send all your test parts to me. Lets start with some side draft carbs!!

Pat
 
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