The Bronze "Plumber" L-Panifold is a specially engineered cast silicone bronze intake manifold for stock 74" Harley Knucklehead and Panheads '40 to '54 with stock cylinder height of 5.330" which is the stock height on a 74" Harley big twin. The overall width of this manifold is 3.5625". These bronze Panifolds are a special edition and will be produced in very small numbers. The Panifold features radius corners and a direction "Y" shape inside. This shape helps the flow and delivery of the air/fuel mixture to the combustion chambers. The overall increase in flow is nearly 25% above the stock design!! The bench flow testing was done by Hasslegren Engineering, a high end race engine building shop. The L-Panifold comes with intake port nuts and brass compression seals . The flange will bolt up to any Linkert carb using the standard 4 hole mounting bolt pattern. This product is 100% American made!