Broken venturi

M

Mad Mac

Senior Member
Bought a Zenith carby with a broken venturi at a swap meet. I tried unsuccessfully to drill it out, using very small drill bits at first then larger drills but it still won't come out. After using the search function here, I found that I should have used heat and I will try that next. In the meantime do you thinkI have ruined it? (see pic).
 

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I don't know if you ruined it but I got mine out with heat, melted out like solder. Just work safe, wear glasses, gloves and something to cover your face in case it splatters
 
pretty rough casting. The heavy corrosion along the upper edge will be a problem.
I made a Venturi extractor with threaded rod and flat washers that press out the Venturi. Haven't used heat to melt out the Venturi. You could melt the brass plugs also.
 
I agree with hotrod farm truck #2. Heat is your only hope on this one, and do take all the safety precautions mentioned... its unlikely to pop out with heat and thermal shock alone so melting it is probably the way to go
 
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This is the safest way to remove both upper and lower halves of broken venturi.

I have removed hundreds of these with similar tool.

https://www.snydersantiqueauto.com/product.htm?pid=979475&cat=41661

If you decide to make your own tool be very sure that the disk which goes inside broken venturi and screws on the threaded rod is the correct diameter.

If disk is too large It will destroy the "shelf" in lower casting making lower casting a piece of junk.


Wear a full face shield if you decide to use heat to remove.

This is very dangerous I had 10 or 20 venturis Explode and spray chunks of metal around.

It makes a sound like a shotgun blast and chunks go flying around.

Drilling or using a hacksaw blade destroys MANY castings

Many castings are damaged in various ways using drills and saw blades.
 
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Good for you Benson, but I have had next to no success with such tools. ( and that's even when I follow the instructions too!)
 
Pretty scabby looking, don't think I'd waste time trying to rebuild it unless you're looking for a challenge. As Brentwood Bob said, with the rough and corroded condition of the top mating surface, you're likely to have sealing problems. I'd trash it and find a more worthy candidate!
 
I couldn’t remove screws and jets from a carb, soaked in Evaporust and the screws and jets came right out, this may help with the venturi
 
I've done the heat and it works QUICK. Not much "solidus" in the transition from solid to liquid.

Problem for me then was the replacement venturi are "small" in diameter. Like shuck around small. Only pinching between the upper and lower halves of the carb and using the gasket worked to hold it.

The carb seemed to work as normal once restored. Zenith are not my fave.

Joe K
 
Thanks Guys for your helpful suggestions. The casting looks bad because it still has the old gasket attached. Will try heat next.
Mac
 
Just to round off this thread: In the end I decided to make a pulling tool. This was a 1.175-inch "plug" that I pressed through with a hydraulic press. Once the plug was made on the lathe, the rest was very quick and easy.
Mac
 
It should be noted that with the lower casting the venturi needs to come out from the top of the casting.

If venturi is pressed down into the casting, the shelf inside the casting will be broken off.
 
Mad Mac said:
I decided to make a pulling tool. This was a 1.175-inch "plug" that I pressed through with a hydraulic press.
Click to expand...

He probably went through the main jet opening to press the venturi out.
 
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Sorry, I should have explained: I decided to use a different lower casing without a stuck venturi, so I was pressing the broken venturi only out of the top casing. It is of course impossible to press a broken venturi out of the bottom casing - only a puller (or melting) could achieve that.
 
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