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Carburtror Leaking


Curti

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I have a 35 Auburn six cylinder with a Carter W1 307s. Prior to installing the carb I took the top off for inspection and at that time removed every plug that I could, and blew carb cleaner thru every orifice. I put it on the car and test run it in my shop. The car runs like a clock. I have an Airtex electric pump that runs through stock a working AC pump, with no regulator. I have this combination on other Auburns that utilize Stromberg EE1 and EX32 with no problem. Now I drive a mile or so and gas in poring out of the top of the carb. (this is scary) A needle and seat problem. Strange that it will run in the shop just fine and drive it and it leaks. Can a person buy just a needle and seat for a W1? Or maybe, I should send the carb to a builder? Does any one know a good Carter rebuilder.

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Curti: Despite the fact that the electric supplemental pump and the stock AC mechanical pump have worked well without regulation on your other cars, I'd add a regulator as a first step because the electric pump may be overwhelming the needle valve and seat. I use a Holley #12-804 adjustable pressure regulator available at performance shops, about $35-40. Holley also offers a dial gauge to display pressure which is comforting but not essential. Three psi should be plenty. I recommend strongly **against** using the cheap $20 detent-type Chinese-made regulators sold under the Purolator name, as they develop leaks in short order. Are you running the electric full time? I use it only for priming and under potential vapor-lock conditions. When the electric is used as a part-time supplement, you probably need a bypass line with a check valve for the mechanical pump's draw from the tank to prevent the electric from pumping back to itself. That will almost certainly be required if you bypass the mech pump on the road if it springs a leak.

broker-len: Some of us run the car on the mech pump and use the electric (1) to prime the carb for starting after some period of non-use and (2) under potential vapor-lock conditions.

I agree that you MAY need to change the needle valve and seat. Have you checked the float to ensure it does not have gas in it?

Edited by Grimy
correct typo (see edit history)
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The first thing I would check would be the tank vent.

If the tank vent is not functioning normally, heat from the exhaust could cause significant pressure in the tank to overload the float/fuel valve combination.

And to add to Grimy's comment: the $20. Chinese-made dial type regulator actually is quite useful.................but ONLY if you have a strong arm, and a rabbit problem in your garden!

Jon.

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Grimy, thanks for the informative post. Holly 12-804 is on the to buy list. I like to run the electric thru the manual pump. I once had a Carter vein pump go south and the manual pump pulled gas right thru it. Jon, I always drill an 1/8 hole high in the gas tank filler neck to insure venting. This is particularly important with a King Sealy gas gage. I have four of those Chinese regulators and never entertained putting one on any of my cars. I do have a rabbit that I would like to get rid of, thanks for the hint. The car starts and runs fine in the shop, so I doubt the float is full of gas. I think I would like to replace the needle and seat, Jon, what would you recommend?

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Curt - we make rebuilding kits that include the fuel valve a.k.a. needle and seat.

I personally do NOT think this is the issue. If the fuel valve were bad, it would fail in the shop, just as in driving. I think the pressure to the carburetor is increasing for some reason; thus overcoming the amount of pressure that the float/fuel valve can handle. Why this occurring I do not know. But this is why I asked about the tank vent.

In the FWIW category: many years ago, my wife was having trouble with starting her car in the summer and she could smell gasoline. This before I "quit my day job" and starting doing carbs full time. When I got home in the evening, the car started on the first crank. So I told her I'll check it on Saturday. That Saturday about 11 A.M. I walked out to her car, and was amazed at the puddle of gasoline under the car!!! We were having vandal issues and I had installed a locking (non-vented) gas cap. That particular vehicle utilized a vented gas cap. The Missouri heat pressurized the fuel tank to the extent that it blew gas right through the pump, the fuel valve in the carburetor, and out the top of the carburetor!!!

I changed the cap AND the oil. No further issues.

Jon.

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I ordered the Holly 12-804 off eBay $34 free shipping. Come to think of it, prior to leaving on the first test run I turned the idle way down and took off, when I got back, I left it idling (solely) and raised the hood and it was leaking . Possibly due to the very low gas consumption combined with the fuel pressure, it over powered the fuel valve. I really do appreciate the input fellas. When the regulator is installed, I will let ya know how it goes.

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  • 2 weeks later...
Guest freidhjrme

Can you give me the link of ebay??? What about yahoo??? Is it available there, actually I am not so much expert in searching and all...

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