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Leading vs. Trailing Plugs...

Old 01-04-07, 03:37 AM
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Leading vs. Trailing Plugs...

I asked in the General Rotary Tech Support section already, but I guess nobody noticed the thread since it has been a couple days and I haven't gotten any response.

Basically, I am looking to put in my PFC in the next couple days, but want to give a general tune up first. Is there any *physical* difference between the leading spark plug, and the trailing? Or can I just grab any good quality plug that matches the FD and throw them in either slot?

Anybody have experience with specific plugs and want to suggest getting/staying away from different types? I'm currently running all the basic bolt ons, so I am not pushing crazy HP/Torque numbers requiring the *absolute* top of the line plugs. But I figure a better spark is a better spark, and can never hurt.

Thanks guys,
Levi
Old 01-04-07, 05:53 AM
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yes there is a difference. NGK part numbers are leading: BUR9EQP Trailing: BUR7EQP. Search the FAQ, it has a lot more into on them.
Old 01-04-07, 06:01 AM
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Use BUR9EQP all around and you will be fine.
Old 01-04-07, 08:04 AM
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I think you'd be alright with the stock heat ranges but either way, consider skipping the platinum plugs. They really don't last long enough to justify the cost IMO.
Old 01-04-07, 08:22 AM
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NGK platinum 9's all around work great for me. a guy at an rx7 performance shop told me not to use iridium plugs.
Old 01-04-07, 12:32 PM
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Right on, thanks for all the info guys. I'll just get the NGKs that BAP/GEON has listed. I'm pretty sure it was leading: BUR9EQP and trailing: BUR7EQP when I went in there the other day.. thats what sparked the question and in turn pushed back the PFC install
Old 01-04-07, 12:41 PM
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Originally Posted by JHew84
yes there is a difference. NGK part numbers are leading: BUR9EQP Trailing: BUR7EQP. Search the FAQ, it has a lot more into on them.
Reverse that, 7's are leading (bottom) and 9's are trailing (top).
Old 01-04-07, 12:42 PM
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Originally Posted by fendamonky
Right on, thanks for all the info guys. I'll just get the NGKs that BAP/GEON has listed. I'm pretty sure it was leading: BUR9EQP and trailing: BUR7EQP when I went in there the other day.. thats what sparked the question and in turn pushed back the PFC install
Check Pep Boys. They usually have them in stock and probably cheaper than at Bap Geon. I rarely ever go to that place unless I'm looking for an unusual item.
Have fun. I remember the first time I changed the plugs on my FD....
Old 01-04-07, 03:59 PM
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bought the NGK factory plugs from Mazda. The spark plug boxes were labeled, so you couldn't mix them up. It looked like the leading were an aluminum color, but the trailing were like almost a golden color. have something to do with material or heat range or something?

but yeah, before I put in my Power FC, i did new fuel filter, new plugs, and new o2 sensor.
Old 01-04-07, 06:04 PM
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Denso IRE-31 heat range 9 iridium plugs.
Old 01-04-07, 07:55 PM
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Yeah, I'm actually not really sure where a Pep Boys is in Norfolk Yuichiror. I just went to BapGeon, they didnt have the BUR7/9EQP's so I went with the BUR7/9EQ's.. didn't get them installed though since I wasn't able to get on base (don't have stickers for the 7 yet, and the line at the pass office was LONG) I'll get it done tomorrow, at the very least I will do it in my driveway (though I would prefer the 4 point lift..)

White94RX, yeah.. I just had my fuel filter replaced last week when I was up at RP. If the O2 sensor needs it than I will do that aswell, but I figure the fuel filter, plugs and oil change should be adequate.

Again, thanks for the imput guys.. def appreciated
Old 01-04-07, 08:12 PM
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Some obscure info -

The "heads" of the NGK's used to always be a gold color (yellow zinc plating), which they recently stopped doing and just used some sort of clear coating, so you just see the shiny steel color.

The numbers in the plug (7 and 9) are the heat range - the higher the number, the colder the plug. Colder plugs are a good choice on modified cars - they can foul out easier, but retain less heat, making less of a detonation hot spot. That said, I've yet to see ANYONE foul out 9's in the leading position on a turbo rotary.

There is a physical difference between 7's and 9's - look at the electrode at the center of the plug tip, and look at the porcelain that's down in there. The amount of porcelain shrouding is the difference.

Bone stock car, I'd just stick with 7's and 9's. Any decent mods, go all 9's. If you want to go big horsepower, you can play with the exotic plugs that are VERY pricey many times.

I usually get my plugs from Advance Auto Parts. Not only do they normally have both the platinum and non-platinums in stock, but the price difference for the platinum is VERY minimal, like a buck. Best part is the 1-year no questions warranty. Run the plugs for a year, pull them out, and get a new set of plugs for free. Done that many times. If you're really crafty, get a Ziploc bag, throw the 4 plug boxes and receipt in the bag, and store it until you're ready for a hassle-free return.

Dale
Old 01-04-07, 08:12 PM
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Originally Posted by Mahjik
Reverse that, 7's are leading (bottom) and 9's are trailing (top).
yeah your right, not sure how I mixed those up. If a mod could edit that for me (damn not being able to edit your posts!!!!) it'd be much appreciated.
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