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MG MGB Technical - Problem with Weber conversion

I have a 1978 MG midget with the 1500cc engine. I decided to go with a Weber conversion and bought a 34DGEC Weber with the manifold. So I converted from a side draft to a down draft. When I installed the new carburetor it would not idle or run for any length of time. I would have to pump it continually, then the car would start but immediately go up to 5000 rpm or higher and then drop down and stall. This is the only thing the carb would go. Even feathering the throttle wouldn't keep it running. I know it's getting gas because I can see it pumped into the venturi when I move the throttle back and forth. I contacted Weber US and they gave me another replacement carburetor that did exactly the same thing. After much frustration they sent me a 3236 Weber that is also doing the exact same thing. None will idle. I'm at my wits end as to what is causing this strange behavior. The original Stromberg was running fine. I'm about ready to put that one back on. These Weber carbs are very simple, so I can't see what the problem is unless it's just a bad new carb. Any suggestions out there?
RKO Russ

To me it sounds like you are sucking air. I think that you have a leak between the intake manifold and the cylinder head. Triple check everything for fit as something is holding the intake manifold from sealing to the head.
If you have a propane torch turn it on unlit and play it along the manifold to gasket area while someone else starts the car. If it continues to run you have found the culprit.
Sandy
SANDY SANDERS

thanks, I'll give it a try.
RKO Russ

This thread was discussed between 27/10/2009 and 28/10/2009

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