Re: install a tell tale on a 64 40hp????
Feeling lucky? Look on the port side of the powerhead. Forward of the second head bolt down, you will see a round boss cast on the block. If you are lucky, it may have a plug screwed in to it. If so, remove the plug, screw in a hose nipple fitting, and you are good to go.
If just a hole with no plug, no problem. Drill through the bottom of the hole, just into the water jacket. STOP drilling when you hit air. If you keep drilling through the cylinder wall---well you get the picture. OK, now tap threads in the hole with a 1/8" NPT (pipe thread) tap. You are now ready for a hose nipple fitting.
Use a fairly small diameter hose, but don't worry about losing too much cooling water. That hole was originally there for water flow to the automatic choke on earlier models.