General info for do-it-yourself'rs.
12 Years ago, I restored an old Mercury 40 HP (4 cylinder) built in the 70's for racing. I learned of several problems and found single simple solution.
1) I needed a tell-tale.
2) I wanted to control that water stream because it takes away from cold water flow down through the engine water jackets.
3) The uppermost cylinder will be the hottest because air bubbles from cavitation, planing, various prop & keel turbulances, etc., are pulled in by the water pump and accumulate in the water jacket around the uppermost cylinder. These air bubbles do ACCUMULATE or build up during normal operation and heat the top cylinder higher than it should be on every engine. I wanted those bubbles removed as soon as they occured.
The solution was simple. Drill and tap the highest point in the water jacket where the cold water from the pump enters the engine. Very often this is the area where the thermostat resides. Use a brass bleeder valve and adjust for a very small stream. You will see some "sputtering" now and then. This is good because the sputtering is the release of the trapped air pockets and bubbles during the pee'ing.
Another trick some of you might like is keeping a lid on an engines temperature. I installed a fixed temperature gauge (precision dial type) visible on the outside of the cowling. The stem of the gauge was CLAMPED to a head bolt at the top with a pre-shaped aluminium strip bent into a "U" and drilled for the head bolt. It could be done easily with a remote digital outdoor sensor. It is very comforting to KNOW your engines temperature on a hot day when you are busy challenging everything on the water that thinks it is fast.......
Lastly..... Investigate making & mounting speed rails if you want to "scoot".
Larry
(will not go any further into racing topics)
