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jord

Carb Leaking Down

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My 1939- 4 door will not start after sitting for a few day's unless it is primed ,however when I turn on the electric fuel pump to fill the carb I  can then see gas going into the intake manifold when I pump the throttle and it will start easily. So the bowl is draining, will a carb kit fix this. She has had some back fires earlier which I read on the site will take out some part of the carb. Also noticed some surging. Mine is a 06H carb 4 hole base it was rebuilt then sat for a few years. 

Next if am to remove the carb I was thinking of adding a pvc system, I already have a threaded hole at the front of the intake manifold so if I install a base below the carb with holes to the throat of the carb what kind of pvc valve would be ok or just feed it directly 

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The bowl probably isn't draining, the gas is evaporating. If you park the car for more than 4 or 5 days, the fuel in bowl will evaporate. Seriously, it evaporates that fast. Next time you're mowing the lawn, sprinkle a little on the ground and watch how fast it disappears.

 

The electric pump is the best solution and seems to working as it should. Sadly, with today's gas, this is normal for old cars.

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You gas is probably draining from the power valve. It or its gasket is leaking. A carb kit will give you a new gasket and power valve, but there are other issues that can make sealing this difficult.

 

I recommend that you send your carburetor to Charlie Schwendler in NY for rebuild. He will machine the carburetor bowl to ensure that the power valve gasket seals and so that there is proper vacuum to operate the power valve. Your mention of backfires, leads me to believe that you may have a small vacuum leak between the bowl and the base of the carburetor.

 

You can contact Charlie at  cas5845@yahoo.com

 

My 40 Merc uses a similar carburetor and it starts fine after sitting several weeks. It takes about 15 seconds of cranking after sitting all winter, otherwise it starts immediately all summer, so I don't buy the evaporation theory.

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I have found that the bottom of the main body of this style carb to be badly warped and will not seal and also the power valve may also touch the floor of the cast base.  I remachine the bottom of the main body and spot face of the power valve sealing area.

I then check the depth of the power valve recess in the cast base. To do this I screw in the power valve (hand tight) with the gasket then mount the carb base with out the gasket and check the fit. Machine the depth in the cast base as required this area needs to fit well as it seals the two idle well holes and the power valve vac. hole. The well in the cast base on the 06h seems be shallower than the newer bases and power valves can vary in hight.

 

my findings,

jonnyd

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Best to fit  PCV valve, prevents any backfires into valley valve  chamber.   Some carbs. have a vacuum connection, don't need base below carburetor.  

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