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Carter WCFB leak question

Started by Bronze, December 19, 2019, 05:15:52 PM

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Bronze

Hi all,
I gave myself a rebuild kit for my wcfb carb that sits on my 56 Convertible. The car is running decent enough but there is one thing i don't understand. When the car has been sitting for a longer time, i "prime" it by dropping a small amount of gas straight down the carb. Works fine for starting the car but every time i do it gas comes out at the base of the carb and drips over the manifold. Initially i was sure there was something wrong with the gasket and as i happen to have a spare carb i have tried with both carbs and new gaskets and same thing happens! Is this normal behavior? This is 2 years since a decided to leave it as it is as the car runs ok anyway, but now that i am rebuilding the carb i want to make sure it's right. On the other hand if gas can leak out from the carb at the base, is it not also a sign of a vacuum leak? I drop that shot of extra gas on the secondaries as the choke is in the way on the primaries...

"Cadillac Kid" Greg Surfas 15364

Next time hold the choke open enough to get the gas down the primaries and see what happens.  It might be that the secondary throttle shaft is worn enough to pass some of the raw gas you are pouring down the secondaries.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

James Landi

As Greg suggests, this is "normal" if you're pouring gas into the in take --- however, you SHOULD be able to start your car by simply pumping the gas pedal three times.   With the engine OFF, and using a flashlight, you should see gas streaming into  the intake when you pump the accelerator lever. from the accelerator pump (aka "traffic pump") in your carburetor.  That dual spray is meant to "prime" the engine when cold, and also give you quick acceleration in traffic.  If you don't see any spray, you've got a problem with your rebuilt carburetor---   First check for spray from the pump before you take any additional measures.    James.

fishnjim

Leaking out, probably from the closed throttle plate ends, because you're putting way too much in.
I use a big hobby syringe, and put 20 cc's (~1 ounce) in w/ choke/throttle open, to start when they aren't getting fuel on their own.   That's more than enough.  You can flood easily with too much gas(>UFL) and it won't start at all after that.   May have to repeat once, if it dies off or doens't catch.   If it doesn't run, after 2, then you have a fuel or ignition system issue to solve.
Some use a ketchup style squeeze bottle, but for me that's not measured.   Dangerous if you using a gas can or open container.

Bronze

All, thanks for good hints and suggestions!
N.B. The carb is Not rebuilt yet, that's why I have not investigated further until now. Sure, I may be pouring a bit too much in but I have never flooded it, it always starts on the amount i put in. 20 cc's sounds like what i put in it.
So yes , i am now starting the rebuild and will have the acc pump and all renovated with fresh seals.
But i am still unclear on the leaking.  Greg suggests worn shafts, but to my recollection the leak comes around the base, looks like it seeps at the base gasket, but it is fresh. James says it is "normal" if i throw gas down the intake.
So, my question is, except for worn shafts, is there a "normal" way for fluid gas to find it's way out of the intake and out on the manifold, there seems to be small channels from the intake that ends up in the cavities in the base ?
And if such a passage exists, via worn shafts or not, would it not also cause an air leak that for example could explain problems to adjust the idle speed?

James Landi

Greg's diagnoses is likely correct.  With the accelerator absolute closed, as in idle position, the gasoline you pour down the throat simply drips out of the shafts on each side of the housing... so while the shafts are relatively tight fitting, gas will leak. Follow the directions for rebuilding with great care, and make sure to use COMPRESSED air through the low speed passage ways as they often accumulate a bunch of crud that will make your nuts if the interior is not absolutely free from obstruction.  Shooting carburetor cleaning is usually NOT enough to drive out the fuel separated crud--- compressed air is the answer.    James

Bronze

Thanks for clarifying! Will do that. Also will soak parts in acetone that have worked well for me on other carbs to dissolve old gunk.
Merry X-mas! :)

Bronze

Ok, Time for a picture.
Watch the inserted strings of wire. These small holes at the base comes out just above the throttle plates. Obviously the are meant to be there and provide a possibility for air (hot?) to enter from the base and up to the air intake. the gasket i use and i think is original style ( https://www.tamotor.se/produkt/forgasarfotpackning-7/ ) has a cut out around these little holes that creates a free air passage between the base of the carb and the intake manifold, allowing air to enter that way and get up in the barrels, and in my case it also allows for my shot of gas to run out of the same hole. I think this is how it should be by design but i can't figure out what is the purpose. Any ideas?

Thanks
/Martin

Bronze

Bumping this as i am sure you guys knows the function of these small holes.

Bronze

Answering my own question since i found the answer. It is perfectly normal to have gas running out of these holes if it is poured down on closed throttles. The channels from the bore ending out at the manifold is there to allow warm air to enter and mix with the intake of fresh air.