Diverter cap for water jacket side plate
Since it cannot be known where a hole in the side of the cap will end up after installation, the cap is modified after installation by drilling a 3/8″ hole on the side (to divert water aft and down approximately 45 degrees) and a second 1/4″ hole in the original top of the cap (to divert some incoming water directly across to the manifold side of the engine).
1) If the “T” fitting does not extend in past the back of the side plate by at least three threads, the hole will have to be opened up a bit, using a 3/8″ tapered pipe tap. Don’t overdo the enlarging process in the beginning, and try the “T” fitting frequently to determine the fit of the “T” fitting.
2) After getting three threads (or so) of the “T” fitting through the side plate, dry fit the diverter cap on the end of the “T” fitting, tightening the cap until one of the hex sides faces aft, and down about 45 degrees. Remove the cap and drill a 3/8″ hole in that hex side, and a second 1/4″ hole in the front of the cap. The 1/4″ hole should face in the direction of the manifold side of the engine.
NOTE 1: Because the stem of the 3/8″ “T” is a tapered pipe thread, it is not possible to know on which side of the hex head the 3/8″ hole will need to be drilled until the cap has been actually “dry fitted” to the “T”.
3) Reinstall the cap on the end of the “T” fitting using a good sealer. Permatex Cold-Weld works well on the stem of the “T” fitting and on the inside threads of the cap itself.
NOTE 2: As an alternative to dry fitting the cap and removing it for drilling the holes as per step (2) above, the cap can be installed using JB Weld, making sure that one of the flat spots in the hex head faces aft and down approximately 45 degrees, and then drilling the two holes with the cap mounted on the back of the plate.