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View Full Version : #2 & #3 spark plugs white #1 & #4 black soot



cousindave
03-02-2011, 11:15 AM
Changing spark plugs noticed two were white two weresooty could valves need adjustment? Thanks all!

jac04
03-02-2011, 11:51 AM
Were all the plugs the same (heat range, etc.)?
Post close-up pics if you can.

Black sooty could be too rich or too cold of a plug. White could be too lean or too hot of a plug. Both at once = ??

Google how to read spark plugs and you will get to see lots of pictures of different plug conditions.

cousindave
03-02-2011, 12:45 PM
Yes all four plugs are the same heat range. Yeah having both two different readings are weird. I'm m wondering if I have an air bubble in the engine that would make 2 & 3 white. Or if tappets are off. Curious. I' ll post picks asap. Thanks

bkreutz
03-02-2011, 02:17 PM
Are you sure about which cylinders are which? typically the center two (2&3) would be richer (darker) than the outside two (1&4) because of the differing lengths of the intake runners. Since the carb sits in the center the center two get a slightly richer mixture than the outer two. (normally not as significant as you're describing though), possibly two of the wires having intermittent misfire or low voltage? Just speculating.

cousindave
03-02-2011, 02:52 PM
Yes it was 2 & 3. Funny thing is she was driving really well with no signs of hesitation or backfiring.

Sputnicker
03-03-2011, 01:56 PM
Unusual. Could be a vacuum leak on 2 & 3? Weak spark on 1 & 4? Compression differences?