97 4.3 blazer with horizontal distributer cap. i took it off to clean it because i have a rough idle. When i turn cap upside down it appears to be firing late because the carbon deposits/arc marks where rotor button transfers spark to cap. looks like it fires after it passes each pole. i may be wrong but it seems like it should fire as it passes the pole not after. i read on different post that these distributers wear out and I may need new one. anybody have anything they could help me with or shed some light on this for me

 

Well, yeah the gears on the distributors do wear out sometimes. This is certainly possible. I would likely clean the cap or replace it and see if you still have a rough idle. If it's smooth again, I wouldn't worry too much about it.

If it's still idling rough and you want to make an $80 investment a new distributor isn't a bad one, especially if you have a 97 with the original on there. They have improved them a bit since the original. I was surprised how much nicer the new one was than the one that was on my 2000.