Why does my carburetor keep flooding my motor?

jayocular

Member
i have a 56 buick and my motor keeps flooding .it is the rochester 4gc carburetor.the floats have been triple checked on measurement and are fine.plus,this carb has a screw at both primary and secondary chambers so if your floats are too high,the gas will come out when you remove the screws and it isnt so i know its probably not the floats.the jets are the proper size.the fuel pressure is right at 4 pounds when running which is normal.the carb has been completely rebuilt and new everything.ive checked that the needle valvse are clean and do not over tighten them.
b4 it floods the plugs,it starts right up and will run until the engine barely starts to warm up and it will stall.then of course i cant start it due to wet plugs.ive tried leaning it out when it is runnning but it makes no difference.i cant time it without it being warmed up either but it is within range since i static timed it.what gives?
could it be an intake leak?also there are these small holes on the carb base stand,1 above each bolt mounting hole that dont seem to make sense.i see drizzles of gas come out of each too when its done running.should those be plugged?are those causing intake leak?they look like they are supposed to be there but dont know if they should be sealed or not.seems to me that there should be no holes beneath the carb like that.
 
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Carb.....

One way or another the floats are not doing the job.... like Tom says, they may be filling with gas and sinking... but that said, they should be gas filled when you take them out....I would install new ones.... then if it still does it ,,, then consider that the basic casting may be corroded with time and defective.....
 
when i took them out yesterday to check float measurement again i didnt notice anygas in them but i wasnt paying too close attention either.i will check that out and repost my results...thank you
 
did you compare the needles to see if they are exactly the same. the shoulder could be different, not letting it close completely, or the seat could be damaged/dirt attached.
did you set the float level holding the top level upright?
 
i did adjust the floats that way and they were right on.the carb also has a drain screw for both primary and secondary bowls and are there to indicate if float level is too high or not when you unscrew them,and no gas comes out when i open them so the floats are doing there job.ive taken out the needles too to make sure they were clean and same thing.
i have another idea,maybe it has air intake leak on the manifold or carb base that causes it to rev high like it is and suck more fuel than needed?
also there are these small holes on the carb base stand,1 above each bolt mounting hole that dont seem to make sense.i see drizzles of gas come out of each too when its done running.should those be plugged?are those causing intake leak?they look like they are supposed to be there but dont know if they should be sealed or not.seems to me that there should be no holes beneath the carb like that.
 
Is this a WCFB??? The sight screws need to be checked with the engine running. The holes you talk about are air bleed holes if we are talking about the same ones. Any pics??? If the adjustment needles don't have any response something is WRONG!!!. Dirt in passages?? Timing???
 
how accurate is your testing?

when there is flooding, fuel constantly flowing into intake and stalling engine.

Several check: If the needle and seat have a particle, dirt or imperfection that will keep it from seating correctly. Fuel will constantly flow. Out of alignment of float, needle and seat crooked. You will see it, by manually checking it. If you didn't blow out the dirt out of carburetur ,it will work it's way inot needle and seat.

Take top off. Tilt the top upside down with neadle and seat closed and floats fitted. Blow air through fuel inlet, where fuel line would go. Air pressure /PSI should be same as fuel pressure, if i remember is around 7 PSI.If Air leaks than needle and seat is no good.There should be absolutley no air coming out.

The float(s) can be easily bent when dissassembling or assembling. Even though you adjusted them. Assembling you have to be very careful. The float arm if bent horizontally will be making contact with inside of carburetor. This will keep the needle from making full contact with seat, thus no stoping of fuel flow.

Last,air out or blow the floats dry of any fuel trapped inside of them. If they are brass, you can solder the leak. They usually leak at the seam or where float joins arm. As a safety measure, you should make sure all fuel is out of float, before soldering.

The fuel Jets will not cause flooding. The jets are for Fuel mixture, idle, and off idle performance, emissions,etc.

The floats have been triple checked? It sounds like you're not doing the work.

JM
 
No adjustment from mixture screws

Mixture screws will not control or cause fuel flooding.

If there is no change , is probably because there is so much fuel/flooding.

Once, you have resolved the fuel flooding than you can adjust mixture screws. If there is no change in idle than it's because the mixture screws have been damaged.

If you over tighten mixture screws, they will be damaged. If you pull out the mixture screws they should have no rings, nail deep grooves in the pointy/chamfered tip.
 
Is this a WCFB??? The sight screws need to be checked with the engine running. The holes you talk about are air bleed holes if we are talking about the same ones. Any pics??? If the adjustment needles don't have any response something is WRONG!!!. Dirt in passages?? Timing???
its not dirty,the needle valves are cleaned and not over tightened and the carb is a rochester 4gc so it isnt airbleed holes,they are holes to check if the floats are too high and the chamber isnt too full(a neat feauture to save on opening to check it,though i still did).
 
when there is flooding, fuel constantly flowing into intake and stalling engine.

Several check: If the needle and seat have a particle, dirt or imperfection that will keep it from seating correctly. Fuel will constantly flow. Out of alignment of float, needle and seat crooked. You will see it, by manually checking it. If you didn't blow out the dirt out of carburetur ,it will work it's way inot needle and seat.

Take top off. Tilt the top upside down with neadle and seat closed and floats fitted. Blow air through fuel inlet, where fuel line would go. Air pressure /PSI should be same as fuel pressure, if i remember is around 7 PSI.If Air leaks than needle and seat is no good.There should be absolutley no air coming out.

The float(s) can be easily bent when dissassembling or assembling. Even though you adjusted them. Assembling you have to be very careful. The float arm if bent horizontally will be making contact with inside of carburetor. This will keep the needle from making full contact with seat, thus no stoping of fuel flow.

Last,air out or blow the floats dry of any fuel trapped inside of them. If they are brass, you can solder the leak. They usually leak at the seam or where float joins arm. As a safety measure, you should make sure all fuel is out of float, before soldering.

The fuel Jets will not cause flooding. The jets are for Fuel mixture, idle, and off idle performance, emissions,etc.

The floats have been triple checked? It sounds like you're not doing the work.

JM
its not dirty,the needle valves are cleaned and not over tightened and the carb is a rochester 4gc so it isnt airbleed holes,they are holes to check if the floats are too high and the chamber isnt too full(a neat feauture to save on opening to check it,though i still did).
 
answer to my problem

ive found the solution to my problem....the choke was actually working in reverse,closing instead of opening and it was doing it because when it was put together,the end of the spring was put on the wrong side of the prong. because the spring kind of hooks at the end,one would think it goes around the prong,it doesnt.also once i got that right i was able to time it,and it was waaaay advanced.now it runs as good as it can though its not firing on 3 of the cylinders....thats another issue along with many to deal with...one problem at a time!at least i got her running after 20 years of not running!
 
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