Leaking Venturi Boosters / Edelbrock Performer 1404

twalace said
Did not see a "Flapper Valve" on the passenger side exhaust system, maybe that is specific for certain year cars??? Did find it interesting the car had a 195* thermostat which I think is a tad too high, also seemed to open erratically when put in boiling water. Dunked it three times with three different results, 1st time didn't open, 2nd time partial opening, 3rd time fully open. Going to replace it with a lower temp t-stat and hope water will flow again through the radiator. When I drained the coolant it had zero rust or particles in it so I think the radiator is in good shape. Do think the erratic t-stat might be contributing to a possible heating of fuel in the carb.

Should look similar to the pic...the big round thing is a weight that opens the flapper valve inside the manifold casting when the engine is warm. When the engine is cold, a spring holds the valve closed to force warm exhaust air up through the crossover passage in the intake and out the drivers side exhaust pipe.Works a bit like a choke. If the valve sticks closed ,it will continue to send heated the air through the intake crossover passage, and in turn, overheat the carb base, which will then percolate the fuel out the boosters.

Seen this numerous times...fixed with blockoff plates over the crossover passage, or a heat shield under thre carb.