Priming a Cold Mixture To start the motor when cold usually there is a priming device attached to carburetor and operated from dash, which serves the purpose of enriching the mixture for starting. Automobile engines draw the mixture into the cylinders by the actio,1 of the pistons. Carburetors are placed below the cylinder head as a matter of convenience. Many multi-cylinder engines have the carburetor on top in the space between the cylinders. With the modern gasoline fuel system the location of the carburetor is a matter of intake design. It is necessary to obtain the best carburetion possible. Accordingly, this instrument is located in a position to accomplish such purpose.