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JanZverina

Continuing Rochester carb issues on my '63

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I had my Rochester 4GC recently rebuilt by a recommended rebuilder here in SD, and upon re-installation this weekend it would fire up briefly and then stall. I checked the factory shop manual and adjusted the idle screws and throttle stop screw to initial recommendations just to get it to run, but still a brief start and stall-out. I checked that the inline gas filter was free and clear and in the right direction. I then cranked the engine with the fuel hose (brand new) end stuck into a bottle and the fuel pump looks to be working fine. I tried a few squirts of starting fluid, but it fired up than died. I also poured some gas into  the carb and it ran for a little bit and then quit. So I don't think fuel is getting into the carb inlet (front and center). I even tried blowing into that brass inlet despite the delicious taste of gas, and it seems obstructed. I remember that on my '60 Electra I could see the gas being squirted into the barrels when I pumped the throttle linkage, but I see nothing like that here. Before I remove the carb and bring it back, does anyone have some ideas as to what else to try or what the problem might be? Pix attached just in case I messed up something, but I took a full set of pix before removal and they match up.

Thanks in advance. 

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Edited by JanZverina
Edit in title - Rochester, not QuadraJet (see edit history)

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The key was not seeing gas squirt. There is a plunger little thing I think called the accelerator pump. That's my guess as it is was squirts the gas

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Thanks, Dales 90. That would make sense, although I thought the accelerator pump only provided that extra squirt of fuel when the gas pedal was pressed hard.

Still, when I pressed on the pedal to try to keep it running, the engine just quit.

 

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FYI,

 

The carburetor you pictured is a Rochester 4GC, not a Quadrajet.  The Quadrajet was only available on the Riviera starting in 1966.  It's a totally different kind of carburetor.  Extremely small primary and extremely large secondary throttle plates.  Because of this arrangement, it's called a 'spread bore' carburetor.  The Rochester 4GC and the Carter AFB are called 'square bore' carburetors.

 

 

 

 

Here's a picture of the base of your 4GC, sometimes referred to as a 4Jet.   Four of the same sized venturi.

 

Image result for rochester 4gc base plate

 

Here's a picture of a Quadrajet base

 

Base Plate Repair

 

 

 

Just a minor difference in the throttle plates, wouldn't you say? the Quadrajet is great for gas mileage and performance on demand.

 

 

Edited by RivNut (see edit history)

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Thanks for the education, Ed. Rochester it is.

Obviously I'm going to take it off and bring it back to the re-builder but I'm still curious as to what those who are more knowledgeable than myself think the cause may be.

 

 

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Before you take it off, buy a large aerosol can of Berryman's B12 chemtool carb cleaner and get someone to start the car while you spray it in the throat

of the carb to see if it will run for a long time if you keep spraying the chemtool for a minute or so. If it does then dies if you quit spraying, gas is not

getting past the needle and seat of the carburetor. This is usually incorrect float level or the needle and seat is just stuck and needs to be unstuck by popping the lid on the carburetor and unsticking it. Also, if the car will keep running if you put your hand over the carburetor to block air flow to the carb, you have a giant vacuum leak (Usually the PCV hose or Brake booster hose disconnected) NEVER and I mean NEVER pour gas into a carb throat unless you want to set your car or yourself on fire. Also, make sure you have the mixture screws screwed out some and not screwed all the way in. Usually the correct setting is about 2 1/2 turns out.

Edited by Seafoam65 (see edit history)

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It sounds as if the fuel valve is stuck in the fuel valve seat.

 

If you shipped the carburetor to the rebuilder, rather than delivered it in person I would test for this.

 

Simply remove the fuel line from the carburetor, and using a source of compressed air, attempt to blow compressed air into the fuel inlet.

 

If this is the issue, once unstuck, you should be good to go.

 

Some of the shipping personnel are wannabee NFL punters ;)

 

Jon.

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