Model 6500 Feedback Carburetor
This unit is basically the same as a Model 5200 carburetor except it has an externally-variable auxiliary fuel metering system in place of the enrichment valve used on the 5200. The auxiliary system is operated by vacuum from the vacuum solenoid regulator under control of the ECU. The Model 6500 carburetor also has a switching bowl vent that allows venting fuel bowl vapors to the canister and a fresh air pickup for the vacuum solenoid regulator.
During wide open throttle, manifold vacuum drops, resulting in little or no vacuum output. The feedback metering valve allows addition fuel to the main well, giving a richer air/fuel mixture for best performance.
One other feature difference, the 6500 carburetor has an internal choke pulldown diaphragm vacuum supply instead of the external vacuum connection on the 5200.