Originally Posted by mcrowe
Also, I am aware that a copper "y" is not a good solution because the copper is not the same desnity as the cast iron block and the knock sensor will not pick up the frequencies it is searching for. With that being said, what about a cast-iron Y fitting?
My friends centurion has a mercruiser engine and it has a cast y with brass threaded fitting in the block on the knock sensor and a plastic "tap" thing in the other hole of the y. When he opened it up, it was completely clogged with junk and he had to take it out anyway and poke a zip-tie around the hole to get anything to drain. Come to think of it, I think he has the plastic taps in a few different spots.
The little tap things look like a good idea on paper but I'm not sure I would trust them.