I have a 95 blazer with a 4.3.
It ran fine but had a tapping sound. I found a rocker arm that wasn't lubing very good so I pulled it out and cleaned it, the oil hole was almost plugged. So I pulled all of them off and cleaned all the rockers and push rods, none of the others were plugged.
I put them all back together and tightened the lifter adjustment nut down until it bottomed out, run out of threads.

Is that what you do with positive stop adjustments?
I've never adjusted positive stop before, but from what I've been told that sounds like how to adjust them.

Anyway, now it won't start back up. It turns over fine but won't start.
It will backfire loud once in a while out the intake, but that's all. Doesn't even act like it is trying to fire off other than the backfire.

I hope someone can help me figure this out.

I do appreciate the help very much.
Thank you all

 

I believe you spin the push rods
while tightening until its snug, stops spinning.

 

Thanks newguy for the help.

I think I figured out the problem. will be a couple of days before I can work on it but will let you know what I find out.

I thought mine were bottom stop heads but there not. so I have to readjust them all and try it again.