Netters and Brian, All engines I have ever come in contact with have to have a small amount of engine heat applied to the air fuel mixture in order to prevent the gas from separating from the mix at part throttle due to internal condensation. This is why even modern multi-port fuel injected cars have coolant circulated at the throttle body to provide a small amount of heat to the mixture, warming the air slightly, before attempting to mix the fuel with it. If not, the engine intake system will cool sufficiently to cause the fuel to condense on the walls of the intake, while the air outruns it into the open cylinder. Then the pooled fuel combines with other fuel condensed and goes into the next cylinder, causing a lean rich lean rich condition. Only race engines run at near to full throttle benefit from complete ram air, and no engine heat. These engines also run poorly, to awful at part throttle, surging, lean cutout, lean/rich surge, stumbling offi-idle prior to accelerating. This is why they have to rev up so high to simply leave the pits, or launch off the line. Plug color is unrevealing unless you do a part throttle run and immediately shut down. Otherwise other running conditions will also be there, so that the plug color will show the entire operation characteristics, not just one range. For good engine performance, a small amount of engine heat keeping the carb alittle warm is necessary for all but wide open throttle operation. Look at Lycomings and Chevrolets. Both have the carbs located where engine heat warms their bases to improve what we called atomization, and fuel mixture retention. Thoughts....
Colin & Bev Rainey KR2(td) crain...@cfl.rr.com Sanford, Florida FLY SAFE!!!!
