82 AMC 258 mis and a little smoke out the pipe

[dwickens1]

Took Olive out for a post windshield install cruise and came back and it now misses and runs rough at idle oh and tell tale blue smoke out the tail pipe (i know not good), any how threw a vacuum gauge on it and acted like a dead cyl with the bouncing needle 16-20 HG. Any thoughts that it may be an easy fix or is it ring/crate motor time, Eng has about 120K on her.

 

[Torxhead]

It could be just an ignition or carb issue. Determine which of the two it is and go from there. Is the miss only at idle?

 

[dwickens1]

Update: pulled the plugs and did compression check and there was oil on the #4 plug, not soaked but a little. that Cyl. had 30 psi where the rest had 135-152 PSI. Wish I had a bore scope to take a peek in there. Rings? I'm going to pull the valve cover as soon as I get a chance to make sure nothing is astray........

 

[johnnyreb]

could be a scored valve and worn valve stem seal too. Might also be a cracked ring.