I'm with Kevin. Rod knock is at twice engine speed, and gets worse as the oil heats up. BTW, yes the timing chain gets hot and expands, but not very much, since it never gets over oil temp, but the sprockets and block and head expand, too, so the clearance stays about the same.

Rod knock does NOT get better with a warm engine, Rod knock is a fairly heavy thunky sound, like hitting the block a good lick with a heavy hammer. Main bearing knock is the same, but louder, like smacking the block with a sledge, a very heavy thunk, thunk. You can feel rod and main knock thru the chassis, usually...

Thanks, guys. It's good to know. I'll pop that timing cover and see about adjusting tension, and probably throw a little Seafoam in before the next oil change.

Almost seems like it's getting better on its own.

If it's got HLAs it could just be them freeing up after sitting so long.

You DON'T have to take the timing cover off to adjust the balance shaft chain. There's an access cover on the case, passenger side about 2/3 of the way down. Remove the little cover, loosen the bolt inside and push the chain guide towards the crankshaft to tighten the chain. Tighten the bolt and replace the cover.

John B.