Need help with Chevy 2.8

Got a carbed 2.8 V-6 in an '85 S-10 Blazer. (not original engine -- omit long sad story )

It's got a noise and I would like to narrow the possibilites down before I decide what to do. (17 year old son flipped his Neon -- didn't even need a band-aid but car is totaled. Yes, he believes in seat belts now )

Noise is a tapping/knocking, seems to be in top left rear of engine. One guy says wrist pin, another says lifter, etc.

It's worse under acceleration, but not always.

What can I check to help narrow down the problem? I've got a stethoscope to help. I've been told to pull plug wires to see if it stops the noise to isolate which cylinder, but is there anything else I can do?

Love to put a 3.4 in it, but can't find one, etc, etc, etc.

 

2.8-3.1 engines sometimes loose a rod bearing. Due to the GM aluminum oil pump wearing out. When this happens it is common for the piston to hit the head on each revolution and sound like the problem is on top. If the noise is approx 1/2 engine speed it may be a pin or broken/galled skirt

 

Put some top lube in it for vavles and lifters and run a tank of super high test in the tank. My 92 pu has v6 always ran high test in it started to use low grade an the knock started same as what you describe.Try that first.

 

P.S just like fat hack said.I had one blow a hole through a water passage.

 

well what did you find out