'53 Holly Carburetor Troubles

29spcoupe

29spcoupe

Well-known member
I have a holly carb that has been rebuilt by a reputable man who is 50 yrs in the business. The carburetor seems to loose its prime when sitting for a few days. Sometimes it seems to do this when only sitting for a few hours. Plugs have been changed and gapped to .030. Is this problem normal for holly carbs? Should I be looking at a new carburetor or keep the rebuilt?
 
Keep the carb, that is normal to a degree. The engine gets hot enough to boil the fuel out of the float bowel, once the car is turned off. Usually I find I can go a coupe of days and there will still be sufficient gas in the carb to start the car. I think the factory fuel pump is a bit weak, so it take numerous cycles before *** will sufficiently replace the gas in the float bowel to start the car. Hence one of the two reasons I have a flow through electric fuel pump too. I can flip on the switch to the electric pump and it will l refill the float bowel, so I can start the car on the first or second revolution of the engine. The second reason to have a flow through electric pump is to clear vapor lock.

Bottom line the problem is not the carb but heat and the lower boiling point of modern day fuels.

And that's my opinion, based on my personal experience and it is free. Take it for what's its't worth.
 
While I agree that this may be normal, I would check to see if the power valve wasn't leaking. Bad gaskets or the wrong PV can do this. I would remove the carburetor from the car, and remove the top of the carb. Then, place it in a pan and fill the float chamber with gas and put something on top of it (paper towel?) to inhibit evaporation. Let it sit overnight and check it in the morning. If the level is significantly lower, you have a problem. Either the gasket is bad and needs to be replaced, or you may have the wrong power valve. PV's for latter Holley 4-BBL's look almost the same and will even screw into the float bowl, but the seating method is different from the earlier units. Make sure you have the correct PV.
 
The man who rebuilt the carburetor has been in business in Poughkeepsie for more than 50 years and is well regarded. I did use the old gasket, so I will use the new gasket that came with the rebuild. Thanks for the tip.
 
I set the float down about 1/4 inch compared to factory specifications for carburetors that will be running gas containing ethanol. That stops the fuel boiling down into the carburetor on a hot shut down.

The 1/4 inch was determined by trial and error with a Stromberg 97 carburetor where you can see the fuel level with the top off. Setting the float this way resulted in fuel level where it would be with non-ethanol gas and a stock float level.
 
I eliminated my problem by doing away with any fuel containing ethanol worst thing you can do is use that fuel in anything with a carb
 
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