Repairing Warped Carburetor Parts

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Lurker Carl
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Repairing Warped Carburetor Parts

Postby Lurker Carl » Sun Apr 01, 2018 1:35 pm

Cast Aluminum is Easily Distorted
Castings are warped when you over tightening the screws. This creates massive air and fuel leaks. Someone has been beating on the side of this carburetor, as well. A gorilla mechanic has been here.

Less Obvious Warp
Corrosion on the flange and in the throat indicate another gasket failure. Air leaks in when the engine is running and so did some water when it wasn’t.

Warped flange is the cause, too much force was used to tighten things up.

Fix this with a file, trying to bend those thick ears will break them off.

Repairing Warped Parts
Use a sharp flat file.

File a bit at a time.

Remove only enough material to true the surface.

Check the Mating Surfaces of the Carburetor Castings
File carefully and gently across the surface, over two mounting holes and apply light, even pressure. Don’t remove a lot of material, you are looking for excessively high spots. The high and low areas become visible. I left the idle tube installed because it didn’t want to unscrew and I didn’t want to break it off. There are other obstacles that can not be removed, take care you don’t bugger them up with the file.

Bowl assembly looks good.

Throttle body looks less good.

See tips in this attachments:

Easy Does It
The throttle body warps because too much force is applied when tightening the 4 screws holding the halves together. Since the 4 screw areas are essentially bent down, force must be applied between the screws to even things out. Put washers, or nuts in this case because it’s easier to see in a picture, as shown between the halves at each of the 4 screws and snug them down. Not too tight.

Don’t Over Do It, Take Baby Steps
Apply a little force at a time, then disassemble and check your progress. The aluminum castings are soft and brittle, but not nearly as brittle as cast iron. They will break if too much pressure is applied.

Same Idea, Different Method
A vice and wood blocks are used to apply pressure at various high points on the throttle body. Washers are used between the castings, because their small thickness limits how much the casting can bend. This is trial and error, experiment with different ways of forcing the throttle body back into shape.

Do whatever works, but do it carefully. The shape of the castings make them difficult to work with. Don’t use a tool that could gouge or create ‘teeth’ marks on the castings. I’m sure some industrious folks could make a jig that gently and securely holds the castings while allowing enough force to be applied to various trouble spots. I straightened each carburetor in under one hour without creating a bigger problem than I started with.

Someone or something whacked the bowl casting hard enough to bend it inward. The float hangs up on the bent casting, creating fuel floods or starvation. Very schizophrenic. Easily fixed with a small C-clamp working up and down the bowl, several trips taking baby steps.




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