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-   -   Drivetrain What's the gap on the plugs? (https://www.northamericanmotoring.com/forums/drivetrain-cooper-s/138639-whats-the-gap-on-the-plugs.html)

grillhands May 3, 2008 07:08 AM

What's the gap on the plugs?
 
A friend of mine looked at my dyno chart and said my gaps on the spark plugs where to small because at the top end of the chart, the curve started to flutter. He said it was from the blower blowing on the spark and causing it to diminish a bit almost blowing them out. Has anyone heard of this before?

CmdrVimes May 3, 2008 07:29 AM

If you are running stock multi-ground plugs then I seriously doubt that was the problem. What RPM did you run the car up to on the dyno?

grillhands May 3, 2008 08:28 AM


Originally Posted by CmdrVimes (Post 2206007)
If you are running stock multi-ground plugs then I seriously doubt that was the problem. What RPM did you run the car up to on the dyno?

I have the NGK plugs that mini-madness sells. I believe it was 7.3k rpm.

minihune May 3, 2008 08:40 AM

Plugs, stock or aftermarket in the correct temperature range are pre-gapped and you can usually just install them.

grillhands May 3, 2008 08:46 AM


Originally Posted by minihune (Post 2206071)
Plugs, stock or aftermarket in the correct temperature range are pre-gapped and you can usually just install them.

I had these plugs in for a over a year. How often should they be changed?

minihune May 3, 2008 09:25 AM


Originally Posted by grillhands (Post 2205985)
A friend of mine looked at my dyno chart and said my gaps on the spark plugs where to small because at the top end of the chart, the curve started to flutter. He said it was from the blower blowing on the spark and causing it to diminish a bit almost blowing them out. Has anyone heard of this before?

You might check with Jan at RMW or Eric at helix13 about that.

Your plugs are probably OK. You might check the wires and make sure the plugs are securely seated (not over tightened).

NGK makes many plugs (copper, Iridium and Platinum)
If you have these, they should last longer than one year-
http://www.mini-madness.com/index.as...PROD&ProdID=71

I have ND IK-22 plugs for the last 3 years and they are working fine.
http://www.outmotoring.com/mini-coop...ark-plugs.html
About $66 for set of 4. IK-20 for stock MCS.

These will work as well for $30 a set of four.
http://www.outmotoring.com/mini-coop...er_spark_plugs

Platinum or Iridium plugs last a long time.
Copper Cores- replace every 15,000 miles or about once a year.

billzcat1 May 3, 2008 09:20 PM

"Blowing out the spark" is a symptom of too large gap - when the charged mixture is too dense for the spark to bridge the gap between cathode and electrode, the spark will be "blown out". The solution would be to tighten the gap a hair or increase voltage at the plug through a high performance ignition...

However, to my knowledge this really hasn't been a problem with Minis. One thing you may be seeing is from faulty plug wires - at high load with a desnse change, your plug wires may be choosing to ground to the head/spark plug tubes rather than the plug itself.

I'd try a fresh set of plugs and replacing the plug wires and see if there's an improvement.

grillhands May 3, 2008 11:24 PM

I'm going to go with aftermarket wires to see if there is a difference. I'm sure it's something that can't be felt in the performance field but it sure is worth the peace of mind.

Guest May 3, 2008 11:36 PM

You're better off keeping stock wires. All the testing that i've seen done on aftermarket ignitions has shown that it's either a complete waste, or causes issues with misfire, etc.

The stock wires have been tested on cars with over 600 whp, they're fine, and do not represent any type of performance barrier.

grillhands May 4, 2008 09:08 AM

I'll probably then go to a dealer and get a set. Thanks for your help

Guest May 4, 2008 09:39 AM


Originally Posted by grillhands (Post 2207181)
I'll probably then go to a dealer and get a set. Thanks for your help

I'd check the coilpack before the wires. It's unusual for wires to cause an issue like the one you're talking about. The coilpack dying off at upper RPM's COULD explain it, but for all 4 plug wires to go out at the same time seems unlikely. Try swapping out the coilpack with someone else's?


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