Spark plug diag question

[dcraigbrown]

I've posted a few times here and haven't really said thanks for all the help- I really appreciate it. Hopefull soon I'll get more involved but at the moment my 73 is still in pretty embarrasing shape.

Well here's my question:

The spark plugs in my 1,2, and 3 cylinders are black and in 4, 5, and 6 they're almost new looking. Since replacing the plugs I've only driven the car approx 50 miles so almost new looking plugs isn't surprising but given the different conditions I assume the carbs aren't tuned correctly. Would the black plugs indicate a rich condition? I've gone through the basics on the carbs. Cleaned them, set the mixture nuts to 2 1/2 turns, and balanced them by feeling the vacuum at the intake port. I'm not too concerned about getting them perfect yet due to higher priorities but hopefully someone can point me in the right direction. I live in Colorado at around 6500ft so getting the mixture right is a challenge, not much O2 up here.

I'll throw this in also but if its not kosher to throw in more than one problem per post just ignore.

Compression checks show about 140 -150psi in all cylinders. After putting a teaspoon of oil in the cylinders it jumps by about 30psi. This makes me suspect the rings are worn, however a leakdown test shows virtually 0% leakage on all cylinders. The tester might be out of cal but I can barely hear a hiss out of the oil dip stick port. Does this sound strange?

[ktm]

Yes, black plugs on 1, 2 and 3 are indicative of a rich condition. You may have enough fuel, but not enough air. You need to balance the carbs using a synchrometer, not "feeling" the vacuum.

If 4, 5, and 6 look "new", then you are probably lean. The plug tips should be brownish. Do a Google search about reading plugs. There are some great photos showing what to look for when reading them.

[dcraigbrown]

I did figure out what the problem was here. The front carb's choke was not sdjuated correctly- slightly open all the time.

[TomoHawk]

This is a good place to start learning about reading spark plugs.

[beandip]

I am glad you found the problem. What needles are in your SUs ? I recently bought a set of S Us from up there and they had 58 needles. Too lean for us flat landers but you might check yours. I am running 54s but I am at near sea level. Just a thought.

Gary

[dcraigbrown]

I'm not sure what needles I have. Any way to tell visibly on the needles.