Club Cobra - Oh foul plugs...

Club Cobra (http://www.clubcobra.com/forums/)

- Shop Talk (http://www.clubcobra.com/forums/shop-talk/)

- - Oh foul plugs... (http://www.clubcobra.com/forums/shop-talk/72412-oh-foul-plugs.html)

Oh foul plugs...

Pulled the plugs today to try and see if I have any ability to do a "reading." (Can't help but think of the psychic hotline when I hear about people reading plugs :LOL: )

Needless to say, #1 plug was pretty easy - it's covered in black soot ie carbon fouling. #2 and #3 look relatively ok and if anything too clean and indicating perhaps too much advance. #4 seems between the 2 and probably the most normal looking.

So, one thing I can't seem to find an answer on is, what do you do when you have completely different looking plugs? I can't say I've been overly scientific about this and should probably start with a new clean set to make sure I'm getting an accurate read on current engine set-up.

These are Champion RC12YCs. My research also seems to indicate this plug may be too hot for my set-up - 10.5:1 compression, 566 HP, ported aluminum Shelby heads, Edelbrock Performer RPM intake, Mighty Demon 750 with #78 jets front, and #82 rear.

Now looking at NGK plugs in the 6 or 7 temperature range, which would be 1-2 ranges cooler than the current Champions.

Appreciate any help from the ignition mystics out there!
Thanks!
Scott

This doesn't answer your question about what to do when you have plugs that don't look alike but it's by far the best plug reading article I've read.

http://www.4secondsflat.com/Spark_plug_reading.html

Chris

If 2 an 3 look OK then the A/F ratio is probably in the ball park. Sound like the plug is fouled. Replace the fouled plug and put some miles on it. Then check it again.

I am running the champion racing plugs, I don't remember the number, the resistor plugs don't work so well in a high performance engine, with the high voltage output modules, I went to Eldelbrock and found the plugs that they recommend for their heads, try looking up your heads and find the application for them

You should also check your spark plug wires if you have an ohm meter. I had my #2 plug like that. The #2 plug wire was junk. I have tried a few different brands of plugs, and ended up going back to Motorcraft.
Scott

I called the tech line at NGK and they recommended 2 plugs:
V-Power Line: BKR6E-11 stock #2756
Iridium IX Line: BKR6EIX-11 stock # 3764 or BKR7EIX - 11 if I need one cooler

I went with the Iridium IX in the 6 temp range, which is approximately 1 range cooler than the Champions I had that were a 12 range.

Checked the timing and ended up with 22 initial, and 16 mechanical advance for total of 38. Had the lightest springs on the MSD distributor and it appeared from the tach light that it was "all in" before 2000 rpms.

Ran it up and down the road some, getting up to high 5000 rpms, and most of the run at 4000, but also had it ideling quite a while when I was messsing with timing and idle screw adjustment on the carb.

Pulled the plugs tonight and #1 again was showing carbon fouling and #3 was white, with some white residue on the ground strap seeming to indicate too hot.

Scootter, that's a good idea and I will check my wires, but will have to hit the Radio Shack for an ohm meter. Was thinking of some new wires anyway. Hope that's what's happening with #1 as I would guess that if the fouling is because of the jetting being too rich, it would show up on all the plugs.

BTW - CJ428CJ - Don Gould at 4SecondsFlat is who I got my carb from so I've read that paper front to back a couple of times. That's the reading technique I've been going by, and approach to timing, thus the high initial and lower mechanical, which he seems to recommend.
thanks!
Scott

Go for a mult-meter (digital), rather than just an ohm meter.

Sears makes some very nice ones .. and inexpensive too.

Sounds like you might have a (some) bad plug wires. But I would check all the plugs first. You also should do a leak-down (compression test), if the plug wire is OK.