Spark plug gets dark

[Pistacchio sprint 72]

Hello,

Saturday was rally day. I woke up at 6, jumped in the car and drove to pick up my copilot.

The engine was badly sounding. Like on 3 cylinders.

I opened the bonnet and sprayed waters on the exhaust headers to find the faulty cylinder.

Found out number 2. I checked the wire connectivity by using a new plug and i could see the spark.

So decided to remove the spark plug number 2.

It was black and did not spark anymore.

Put the new one instead and drove like i stole it to the rally meeting point.

2 days after the new spark plug number 2 is getting dark. So the mixture is too rich.

Is it that screw i need to close slightly? Thanks

[john.p.clegg]

If only it was as easy as that,you need to determine at what throttle position you are running rich,Gunson Colour tune might help or a rolling road.

John

P.S.
Could also be on the high tension side (rotor,dissy cap,plug lead,plug) that is at fault.

[twincamman]

Not the brass one the one above it 1. 1/4 turn out at 2000 rpm when the motor is hot.....you will hear it come in....also check the rubber o ring isn't leaking ......buy a unysin about. 40 bucks to see the set up is correct .......ed

[RogerFrench]

What are the other plugs like? What plugs do you use?

[Pistacchio sprint 72]

Plug number3 is on the left side of the picture for comparison. Colour is light brown so no problem i would say.

Plugs are iridium ix by ngk
Bpr7eix
4055

[RogerFrench]

Possibly plug lead but I know yours are new so very unlikely to be a problem.
I agree that no. 3 looks OK. Twincamman identified the correct screw.