I have a 83 pickup and it started knocking real bad the thing is it only knocks after you drive and for about 5 mins and get it warm. I cant really pin point were it is coming from it gets worse when you rev it and you can kinda get that mid point in throttle were the knocking gets super bad. I pulled the valve cover and the timing chain looks good. what should I look for the pin point were its coming from I hope its not a rod or main knock but if it is I can deal with that its a trail rig so it not like I cant get to work.

 

If it's from the bottom end, you can test it by putting on emergency brake, add a little throttle, let out clutch slowly putting a load on the engine. If knock gets louder, it is the probably the rod bearings. Since it does it when warm, sounds like when your oil gets thinner, there is more clearance for a rod to knock than when cold.

I have used a long screwdriver or a piece of wood put to the valve cover, other end to your ear, and listen for upper end noise. You can the same to listen to the bottom end, put to oil pan. Or buy one of the auto testing stethoscope, at your local parts store.

 

the timing chain holder is broken of the bolt at the bottom on the driver side but I can almost feel the knock when I hold my hand on the block around the 3ed cylinder