my 460 makes a fairly loud knocking noise coming from the lower end (this problem just started)sounds like a rod knock. i pulled the pan dropped the rod caps and pulled the bearing i found 020 oversize bearings with wear down to the copper underlayment but i dont beleive this could cause a rod to knock all of a sudden but while i was in there i reached into the bottom of the chain cover and the chain felt real slack could this make a knocking sound? any knowledge on this subject would be helpful

 

Timing chain slack can cause the knock also. had this happen to me once.

Wayne 60 F-350
e-mail
https://www.ford-trucks.com/users/whomrig

 

 

yes, a slack timing chain will cause knock too.. the slack gets picked up, then thrown out again and flings the chain around, sometimes hitting it on the cover...causing the knock!

J/.c

1965 Ford Galaxie 500 (okay, so not quite a truck)
460/C6 transplant @ 389hp/491 lb.ft.
14.29@103.8, 13-14 mpg heheheheheh

 

I just rebuilt my 460 and the bearings were pretty worn, although they were not down to the copper. It didn't hold very good oil pressure when warm, but it did NOT knock. BTW, the timing chain was so loose I think I could have taken the chain off without removing the gears. I would really suspect that the sound is a rod knocking in your case.