Technical Rod Knock?

Got an old SBF running, I'm hearing what I think is rod knock. Here's a video. Sound is poor but you can hear it and how correlates to throttle opening. Noisy on throttle opening, quiet on decel. On the road I can hear it under light load at higher RPMs, put a load on it or let off the gas and it goes away. Characteristic of rod noise?

 

Every rod knock motor I've been involved with - put a load on it and it gets louder than all hell, right before it comes thorough the block

 

Sounds like a diesel

 

wrist pins

 

I think your thinking is correct. fordor41 and hotroddon are right. May as well put new bearings in it too...and new pistons...and rings...and t -chain...and a shiny new carb...and machine the...aw hell you can guess the rest.

 

I hear Piston slap, I think you have stuck rings. Run a compression test, it will be very obvious.

 

Stick or automatic ? Could be cracked flexplate. Been setting a long time could be wrist pin.
Noise in top or bottom ? Need to isolate. I had a 400 Pontiac that broke the piston right above the wrist pin. The top of the piston would slide down and touch the rest of the piston and it would knock it up and the noise would go away until it would slide down again. Tough to diagnose.

 

Broken piston skirt, maybe? I know some years of 302 are prone to it. It allows the piston to tilt in the bore enough to hit the head. Eventually it will hammer the rod bearing out, too.

Have you checked the oil pressure?

 

what/where motor from? know any background on it? changed oil? if so, how did old oil look/smell?

 

Thanks guys. There is an idiot light, no oil pressure gauge. I noticed when I fire it up cold it knocks for a couple seconds so I'm thinking it's oil pressure related. I once saw a table on engine knocks, acceleration, decel, cruising, load etc.. Still looking for that, and will hook up an oil pressure gauge.

 

Was told that if you pull the plug wires with motor running. When you get to the rod knocking with plug wire disconnected the bad rod will knock twice rather than once. Without fire it will knock on the power and intake stroke. Never had a chance to see if it worked. LDL

 

Long ago we worked on a '32 roadster with a SBC, when it started... Rod Knock. But sound wasn't consistent, the noise floated about. I had heard the same sound in 350 Olds engines, it was carbon chunks being hammered, soak it down the SBC with a GM additive. Be a cheap 1st try, best of luck. Dyno Dave

 

It works, determination of which hoke is bad isn't worth much though. The whole engine is coming out, the whole thing comes apart and you'll do all of it anyway. It takes just a moment so it's worth doing anyway.

That experience can be used to sell an expensive engine job to those who don't get dirty.

 

SBF's are prone to the cracked skirt syndrome, yours sound textbook...

 

It's a Ford what do you expect?