Quote Originally Posted by francis blake
I want to use a 600 holly 1850 carb on a 4.3v6 I bought a holly conversion kit with smaller jets and power valve to convert it to 400cfm .I am concerned that I may need to retard the opening of the secondarie. Does anyone know how to do this or do I need to or am I wasting my time and money. Thanks for any help. .......Francis
Changing jets and power valve does not change the amount of CFM the carb flows, it only changes the amount of fuel going into the engine. Venturi, air horn, and throttle plate determine the size (CFM rating) of the carb....