Leaking Venturi Boosters / Edelbrock Performer 1404

[65Val]

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.

 

[twalace]

Don't think mine has it, maybe the previous owner removed it??? Since it looks like it will be located to the rear of the car and kind of hidden I will take a look underneath from the passenger side rocker panel and let you know...

 

[65Val]

Don't think mine has it, maybe the previous owner removed it??? Since it looks like it will be located to the rear of the car and kind of hidden I will take a look underneath from the passenger side rocker panel and let you know...

Yours may look different, as the one in the photo is of a later model, but the function is still the same. You should be able to see it from the top. Grab the weight and give a twist. If it moves, then the flapper is probably functioning correctly. If it's stuck, it may be stuck in the closed position, which is no-good. If it's stuck in the open position, you're gold!

The one on my Dart, when I bought the car, was stuck closed. Made the car perform like a DOG! After I freed it up, you could feel the difference.

Yours may look more like this......

 

[twalace]

Found the "Flapper Valve" and it opens & closes freely when you move the weight! Also put in a Stant 180* T-Stat & drilled two 1/8" holes in it to get my coolant flowing again today. Did notice a slight dribble of fuel out of the passenger primary booster again but I have a smooth idle at 750rpm. Guess I will have to try some fine tuning with the idle mixture screws & the vacuum ports on the carb...

Might also try changing the metering rod springs as I am running 15hg on the vacuum advance port.