I have a "Lean out" Valve plumbed to the back of the intake manifold below the carb. A 1/2" hose running from there into the cockpit to a ball valve that is tied to my steering column. I use the valve to lean out the mixture so it builds heat faster. I like to stage at 170 to 180 degrees. I am usually 180 to 190 at the end of the run ( a gain of 10 degrees water temp during the pass)

DO NOT forget to shut off the lean out valve before you make the pass!!!