I used 3 different listening devices (1" dia. oak stick, 3' long 1/2" extension and short length of water hose, wood is best) to try and get a better handle on an exact location in the block. Not much luck, but I did pretty much rule out the fuel pump. Now that said, it's an easy thing to pull the pump and put a plate over the hole to do a real test. May very well add that to the list.

One odd observation I mentioned in the original post, after a bit at low rpm the knock goes away. Happened again today, however bring the rpm up to 1500 or so and it's back, let it idle for 10 minutes or so at low rpm and it goes away.

RonR


RonR


1951 3600 with Clark flatbed, T5, 4.10 rear
1970 340 Duster
1990 5.0 V8 Miata (1990 Mustang Gt Drivetrain)
1964 CJ5