The Edelbrock 1409 Marine Series 600 CFM electric choke carburetor is a precisely tuned, quality-built carburetor that can handle the harsh abuse only a marine environment can inflict. Several characteristics make the 1409 Marine Series 600 CFM electric choke carburetor an outstanding marine performer. The first one is that metering rods are utilized to transition between circuits. The carburetor is unaffected by engine backfires, which means that there are no power valves to blow out, and the rods can be changed in seconds without carburetor removal or fuel draining. Secondly, the carburetor has the unique ability to hold a tune, so once it is tuned, the carburetor stay’s tuned. What this means to you is that compared to other carburetors, the performance remains consistent and the calibration stays unchanged. The lightweight all-aluminum body features a two-piece body that is iridited and assembled with PTFE-coated shafts and pump arm for maximum protection. The simple tub-type bowls and rear-pivot floats all contribute to a carburetor thats reliable, user-friendly and is easily tunable for trouble-free operation. (CALIBRATED FOR PERFORMANCE) Designed and calibrated for optimum marine performance in small-block V8 engines with a variety of manifolds that include Edelbrock Performer, Performer RPM, RPM Air-Gap, Torker II and other brands of similar design. Also ideal for Chevy 4.3L V6 engines with a Performer manifold (see Manifold Section) and Calibration Kit #1485. Comes with: Metering Jets - Primary .098, Secondary .101; Metering Rods - .068 x .047; Step-Up Spring - orange (5 Hg). These carburetors feature venturi diameters of 1-3/16 for the primarys and 1-9/16 for the secondarys. Throttle blade diameters are 1-7/16 for the primarys and of 1-11/16 diameter for the secondarys.