[TedEaton]

I've nothing to back this up with but I'm in the camp that believes the model 4150 development came about as a result of the horsepower race that was developing in the Fifties. The 4V Carter and Rochester carburetors came out in 1952 and were already a dual needle seat design which made those carbs already geared up for the upcoming horsepower race. The first Holley 4V carbs were introduced as the model 2140 in 1953 and evolved further into the model 4000 in 1955. Both the model 2140 and 4000 carbs incorporated a single needle seat design which was good for simplicity purposes but caused problems when the horsepower numbers started rising. The single seat needle design simply could not supply enough fuel. To compound the problem with the single needle seat design, the fuel reservoir was also on the small side so the fuel bowl was prone to emptying even quicker. Hence the development of the dual needle seat model 4150 carbs with ample sized fuel bowls. Just my two cents worth. Feel free to shoot holes in this. Ted Eaton.