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Spark plug diagnosis?
EgeWorks - July 26th, 2004 at 10:51 AM

If a spark plug dies WAY to quickly and when I have a look at it, it has a whitish insulator, no chipping, and a fairly black electrode is it too lean?

(yes this is another stupid guy trying to learn about his car and why it isn't going well)


Bizarre - July 26th, 2004 at 12:19 PM

Sounds way too lean

Have a read on some of these links

http://www.google.com.au/search?q=spark+plug+readings&ie=UTF-8&hl=en&...


EgeWorks - July 26th, 2004 at 03:55 PM

As always you're a legend! I was looking for some good pics like that.

I have one cylinder bank running lean and one running rich... fun times when both mixture adjusters are pretty well the same:) Well it goes to the carby specialists on Wednesday, just gotta get myself there is all!


36 HORSE - July 27th, 2004 at 05:37 PM

Hi Ege Works ( If thats your real name )

Firstly The plug on the left of Blue 74l's photo, may not be too lean. You can't tell from that angle. You need to look deep inside the plug where the insulator meets the steel base of the plug. As long as you have a millimeter thick black ring of soot, then your mixture is rich enough. The centre plug, the one marked perfect, is actually fu#ked because the side post is worn, broken or burned away. And the deposits on the outer end of the insulator suggest it is too cold a plug for that engine. The right heat range plug will keep the end of the insulator looking like new from that angle. The plug on the right is oil soaked. Too rich a mixture leaves fluffy dry soot like in a chimney. Petrol soaked soot usually means that cylinder hasn't been firing. As even the most feable combustion will dry out petrol. If your still with me, I would check the tappet clearence on the cylinders you think are too rich. You might find the valves aren't shutting off. Just a thought. 36 Horse ( not the name my mother gave me )
.


EgeWorks - July 27th, 2004 at 07:02 PM

Thanks for more info 36 Horse. I'll take a look at that too... damn cars...


jnr356 - July 27th, 2004 at 07:16 PM

with the types of fuel available today it is very difficult to "read" spark plugs nowdays


EgeWorks - July 28th, 2004 at 06:55 PM

It turned out to be a bent throttle shaft. Causing the right cylinder bank to dry foul. The ones on the left hand side were a little lean but not too much.

All is good with my engine again. Thank you all for your input.

PS. it is a single 44IDF carb.