KEK

1925 Buick carburetor flooding problem

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Hi everyone -

 

I took my roadster out for another test drive and after driving about 1 or 2 miles it flooded out. Gas was ‘bubbling’ out of the top where there is a valve that looks to be designed for an air pressure release. See photo.  The carburetor is an Marvel for the standard engine that is in the car.

 

I think that the needle is not setting correctly but not sure exactly what the problem is. The float is in pretty good shape for an original. I went through the carburetor and set everything to specs as best I could and made new gaskets. I took the cover off to check the fuel level and it is about 1/8” below the top of the bowl. It seems to flood more often after it warms up but I haven’t ran it enough to verify this is true. I have run it for 10 to 15 minutes at idle with the top off and the float maintained the fuel level without any issues.

 

I am using an electrical fuel pump and have a filter just before the pump. Inside the original vacuum fuel canister on the fire wall I have a small single barrel carburetor. The float in this carburetor controls the fuel level in the canister. I have a wire mesh filter in the bottom of the canister where the fuel gravity drains to the Marvel carburetor. This system works remarkably well.

 

When it flooded out it must have been under some pressure. It doesn’t seem like you would be able to have that much pressure with a gravity feed. I am thinking the problem must be either small particles in the fuel or the needle and seat are worn out. I don’t suppose I can buy a new needle valve anywhere? Any suggestions would be appreciated.

 

Thanks Ken

 

 

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Edited by KEK
To add photo (see edit history)

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The spring loaded valve in the bowl cover is Marvel's early attempt at a "choke" ;)

 

Often referred to as a "flooder" valve; when one needed to start a cold engine in cold weather, one depressed the plunger, which depressed the float, and gasoline went everywhere! But it would create a richer starting mixture.

 

It could also be used to flood the fuel valve and flush any dirt or other debris.

 

Jon.

Edited by carbking (see edit history)
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normal gravity pressure is 1/2 #per foot of elevation.  what pressure  does your electric pump produce?  I assume that you have a needle and seat in the vacuum tank.  This could be leaking and flooding the vacuum tank.

 

Bob Engle

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6 hours ago, carbking said:

The spring loaded valve in the bowl cover is Marvel's early attempt at a "choke" ;)

 

Often referred to as a "flooder" valve; when one needed to start a cold engine in cold weather, one depressed the plunger, which depressed the float, and gasoline went everywhere! 

 

Jon.

 

I just decided to change the way I start my car. I've been opening up the gas adjustment screw by a 180-degree turn to start the car and shut it 180 degree turn once it starts. It's a pain, but pushing the plunger thingy on the float sounds much easier. It's like an early accelerator pump for giving an extra squirt of gas for starting.

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Ken, 

    It is interesting that the needle does well at idle but not at speed.   It may need a little breaking in.  I would also suggest putting in a nitrophyl float.   

    I do not believe replacement needles are available, and the seat is the float bowl.  If someone knows otherwise, please enlighten me.

Inspect the needle.  It should not have a "ring" in the tapered point.  If it does, you will need to have it turned to a smooth cone again on a very small lathe.  If you are lucky and it is still a smooth cone, you can put just a spot of fine valve grinding compound evenly on the taper of the needle.  Not too much.  Follow the instructions below.   I learned this trick from a friend that flies vintage airplanes.   Hugh

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Replacement needles AND seats come in the carburetor rebuilding kit.

 

The trick of chucking the needle in a lathe (with a taper attachment) and then turning out the groove (if a groove is present) will work if the fuel valve seat screws in from the same direction as the needle is inserted, but will no work in this case. 

 

WHY?

 

When one turns out the groove on the needle, one changes the overall length of the needle. To compensate, one must either bend the float arm (guaranteed to break on these early cast brass arms) OR place a thicker washer under the seat if the seat screwed in from the same direction as the needle. Since the seat in this carburetor screws in from the BOTTOM, it would be necessary to remove the seat and either find a thinner washer (good luck) OR chuck the seat in the lathe and remove the corresponding amount of metal from the seating area of the seat.

 

Jon.

Edited by carbking (see edit history)
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Thanks Jon.

 I know Hugh and I have done a bit of lapping of the needles on the carbs we have for our 1925s. Things would seem to work for a while on mine. One carb I adapted a Viton tip to the one needles and had to make a small brass cage for the needle to seek center. That worked well for a while also. On all  3 of the carbs I have worked on I have not been able to remove the seat. I feel if I would torque it anymore it would destroy it. Even after I went strictly with the vacuum tank, when shut down the carb leaks if I do not use my in line ball valve shut off. Even though the vacuum tank valve shut off is closed.

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Larry - you are using the wrong tool to remove the seat ;)

 

Before I describe this...................................it works with brass carbs and cast iron carbs (modified procedure) NOT WITH ZINC ALLOY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

Find the worst BRASS carb you have, so you can try the procedure. Get a pair of vise-grips, a five gallon bucket, a piece of foam rubber, 3 gallons of water, and an acetyline torch (NOT MAPP gas or propane).

 

Put the foam rubber in the bottom of the bucket, and add the water. Grasp the carburetor body with the vise-grips. Turn on the torch. Heat the bottom (where the screw slot is located) of the seat with the torch. Exactly when the color of the flame changes from blue to a greenish-yellow, drop the casting into the bucket of water.

 

Remove the casting from the water, and unscrew the seat.

 

To make this post more generic, for cast iron carburetors:

 

Do everything as above but DO NOT QUENCH IN THE WATER! Let the casting cool naturally.

 

THE CAVIAT: NEVER EVEN THINK ABOUT THE POSSIBILITY OF CONSIDERING HEATING EARLY ZINC ALLOY WITH A TORCH!  IT CAN EXPLODE!

 

Jon

Edited by carbking (see edit history)
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16 hours ago, carbking said:

The spring loaded valve in the bowl cover is Marvel's early attempt at a "choke"

All my Marvel carbs have a choke valve. 

I believe a better term for the button on the bowl cover is a "tickler".  

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Thanks everyone for the terrific input. I learn something new all the time on this forum and these postings are another example. I am also going to start the car now by first pressing the ‘flooder’ value to prime it. 

 

So based on all the input I am going to pull my single barrel carburetor that is in the vacuum fuel canister and replace the needle and seat. Seems like if there is enough pressure in the Marvel to cause it to bubble out of the flooded valve it makes sense that the fuel is not always shutting off in the canister. I am running the fuel pump at one of the lowest settings but if the needle valve isn’t seating then fuel would come out of the flooder valve.

 

I need to run out to my shop and pull the needle out of the Marvel that is on the car and inspect it for the grove on the shaft. I remember reading about that in the Shop Manual but I can’t remember if the needle had a groove or not. I can’t remember if I was able to remove the needle from the carburetor. I also looked through my other Marvel carburetors and found a needle and seat that looks like it may be new.  I might just put this one in the car since it looks so good if I can remove the seat from the other carburetor. If not, I might try Jon’s procedure to remove the seat if I have the courage to heat it up and quench it!  I am familiar with this procedure from trying to remove venturies from my Model A Zenith carburetors but never did attempt to do it.

 

Jon - what parts are in your rebuild kit besides the new needle and seat?

 

Thanks,

Ken

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Hope your float looks and works better than mine.  After my 24 years of ownership and who knows how many seasons before that, my float gave up the ship this spring.  
 

Carved a nice replacement out of nitrophyl.  

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