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Carter AVS 4737 4BBL 1970 440 GTX

Tony 70GTX

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I had the original Carter carburetor, factory tag still on carb, rebuilt about a year ago. Since then if I don’t start the car for approx 2 weeks or a month I have to tap on top of the carburetor float area and she’ll start right up. I didn’t have the issue until the carburetor was rebuild, 6 pumps and she would start right up. The carburetor was taken part to check float, measurement, etc. Once the car is started it will continue to start. The issue is only when it sits for long period of time.

Has anyone heard or experience such an issues?

Replace with Edelbrock AVS?
 
all the fuel has evaporated out of the bowl from the heat of the motor and sitting there is no real way to stop that from happening
 
Tapping on it does nothing, the fuel is evaporated.
 
all the fuel has evaporated out of the bowl from the heat of the motor and sitting there is no real way to stop that from happening
Why didn’t it happen prior to rebuilding the carb? Once I tap the bowl the car starts right up. As if the float is sticking.
 
Why didn’t it happen prior to rebuilding the carb? Once I tap the bowl the car starts right up. As if the float is sticking.
Coincidence. If it was a stuck float it would happen all the time. Letting it sit lets it all evaporate. Crank and pump and it will eventually start.
 
I had the original Carter carburetor, factory tag still on carb, rebuilt about a year ago. Since then if I don’t start the car for approx 2 weeks or a month I have to tap on top of the carburetor float area and she’ll start right up. I didn’t have the issue until the carburetor was rebuild, 6 pumps and she would start right up. The carburetor was taken part to check float, measurement, etc. Once the car is started it will continue to start. The issue is only when it sits for long period of time.

Has anyone heard or experience such an issues?

Replace with Edelbrock AVS?
ABSOLUTELY NOT......THE ORIGINAL CARTER AVS 4737 is a great carb. As far a tapping the float area...it is POSSIBLE that the rebuilder forgot to install the needle valve pull clips.....these clips pull the needle valve away from the needle valve body. They are attached to the float arm. Additionally, did the rebuilder use VITON TIPPED needle valve. Perhaps, the float arms are slightly out of alignment.......just a thought.....
BOB RENTON
 
Last edited:
I would also check that the carb has the 13/16" acc pump plunger, not the slightly smaller 3/4". Easy to mix up.
 
Did you go to a smaller base gasket when it went back on? If you use a thin gasket it will heat soak badly. Somebody put a piece of metal under my carb that couldn’t be seen. When I pulled the carb the first impel I could tell it would basically block some heat until it became soaked and held heat right in the carb. After having dealt with a few avs carbs, I know you need at least a 3/8 spacer to insulate the carb.
 
One of the issues I’ve had repeatedly with my Eddy carb is if the car sits for a month or so, the float needles stick shut. Same on the 2bbl on my 318 poly. On the Eddy carb I have to pull the lid to unstick, on the poly, a few solid raps with a plastic hammer right above the float bowl works like a champ. I think the newer viton tipped needles and modern gas are not friends. I wonder it solid brass needles would solve the problem.
 
Is ethanol gumming the needles up? I run stabilizer all year in all my carb stuff. I haven’t seen a problem like what’s being described here.
 
One of the issues I’ve had repeatedly with my Eddy carb is if the car sits for a month or so, the float needles stick shut. Same on the 2bbl on my 318 poly. On the Eddy carb I have to pull the lid to unstick, on the poly, a few solid raps with a plastic hammer right above the float bowl works like a champ. I think the newerviton tipped needles and modern gas are not friends. I wonder it solid brass needles would solve the problem.
"I think the newer viton tipped needles and modern gas are not friends"......not true..VITON is an excellent elastomer for uuse in a fuel system.....it's impervious to alcohol blended fuels.

Viton® is a specific brand of Fluorocarbon (FKM) and is a registered trademark of The Chemours Company. This synthetic rubber polymer is commonly used in o-ring applications for aircraft engines, automotive fuel handling systems and other applications requiring high temperatures and low compression set.

One of the first steps in designing a rubber seal is choosing the right material for your application. This is a critical stage in development, as every rubber compound carries its own strengths, weaknesses and sealing capabilities. Before choosing Viton® as your trusted material, here’s everything you need to know about it.

Key Strengths​

Viton® has outstanding resistance to heat. In fact, one Viton® o-ring can withstand temperature ranges from -13°F to 446°F. Since some rubber compounds are known to fail in extreme high-temperature environments, Viton® is a great candidate for applications working under these circumstances.

Viton® also is known for its excellent chemical resistance, making it a universal o-ring material. When rubber is introduced to chemicals, it can absorb the fluid like a sponge, causing it to swell. This can be damaging to a seal, since excessive swell can cause premature failure. Chemical compatibility is extremely important during the material selection process to ensure your material will not react when introduced to specific chemicals.

Important Limitations​

While Viton® is resistant to a long list of chemicals, it is not recommended for exposure to:
  • Ketones
  • Amines
  • Low molecular weight esters and ethers
  • Nitro hydrocarbons
  • Hot hydrofluoric or chlorosulfonic acids
  • Skydrol® fluids
In contrast with its high-temperature resistance, Viton® does not retain flexibility at low temperatures, so it is not recommended for low-temperature applications.

Ideal Applications​

With intense versatility and resistance properties, Viton® is typically the right material choice for more heavy-duty applications. Commonly employed in various gasket, o-ring and other rubber sealing solutions, Viton® has become a reliable material for automotive seals, transportation fuel applications and aerospace seals, pumps and valves.
Some info re VITON.....fyi......
BOB RENTON
 
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