Engine Knock 86 K-10

[brownk01]

Hello All. I have an 86 K-10 that I installed a used 350 with 90k. last summer. It has been running great until last weekend when it developed a knock under acceleration. It sounds like a typical detonation knock from low octane fuel but is bad enough that it is un-drivable and it has robbed 25% of the power when knocking. Here is what I have tried to diagnose it one at a time: drained the fuel and replaced with 93 octane, replaced rotor, wires and plugs, inspected EGR, changed carburetor, changed distributor (incl cap and coil), removed timing cover to verify that chain had not jumped a tooth, checked fuel pump for proper pressure, removed exhaust from back of headers, used starting fluid to detect intake/vacuum leaks, do not have a oil gauge but oil light works and is not coming on, changed oil and filter (no signs of metal flake), altered timing (normal/high/low). Does anyone have any other ideas before I pull the engine out and apart? It idles fine and runs perfect (even at high rmps) until it is under a load and does it with the engine cold or hot.

Any thoughts are appreciated.

[BigBlockV6]

Sounds like a typical 350 to me

 

I bet you spun #7 rod bearing its always the one that failed on me well 6 out of 7 350's anyway . . . I replaced them with 400's haven't drop of trouble since

 

400 SBC will fix it

 

 

Mike