Broken flange on Zenith carb

Dick Deegan

Dick Deegan

Well-known member
Along with my stuck piston ring I removed the Zenith carb today due to an air leak and found the flange of the carb which holds the carb to the manifold broken on one side.

Do you think JB Weld would work to put this back together so that it would be serviceable again?

I can also grind it and braze it, but I think that I would have better chance of getting the flange reasonably flat with JB Weld.

Dick
 
Regarding your other active Post: #3 piston ring stuck

Hmm...crack in the carb flange...could a minute piece of the carb flange made its way to cylinder #3 and lodged between the ring and piston? Remote chance but possible.
 
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Ive got one in the shop that has been welded and is my go to "good" carb to throw on a car when carb troubles are a question.
 
You also need to make sure your manifold flange is flat. Some thing caused it to break. Go for the weld better yet get a different carb.
 
George brings up a very good point. Something caused the flange to break. This is a repro manifold that has bee on the car fro a couple of years, but has always been used with a copper gasket - until a few weeks ago. For some reason I decided to use a paper gasket. I'll just bet that the manifold flange is not flat!! I will check tomorrow.

I will also try to braze up the flange tomorrow. However, my good friend Gord by the Bay is going to send me another top with a good flange.

Thanks for all the very good advice - as always.

Dick
 
If you braze it, its good to place it in a box of sand and cover it up good with sand. Do this just as soon as you complete the brazing so it will cool slowly. This is how I was taught. I have brazed manifolds and cylinder heads with chunks broken off when attempting to remove with a screw driver. If the cast iron is clean, you can do a better job without the flux. If flux rods is all you have, I use the wire brush on the bench grinder to first remove the flux. The flux will continue to fester any paint and can't really be completely removed.
 
I had a broken flange on a Zenith that was on the fuel bowl side of the carb. I discovered that the reason it cracked was that someone had used bolts that were too long. The bolt threaded into the flange and protruded down enough to contact the top of the carb. As the bolt was tightened it tried to force its way down onto the top of the carb. The stress broke the flange. Fortunately, the flange was welded back in place and it works fine.
donQ
 
best bet for a carb gasket is cork, use the newer rubberized cork. this way you don't have to tighten the snot out of it to get it to seal. easy to make one
 
I will not use the thick copper gaskets as the ends can be drawn down too tight leaving the center ring to create resistance, causing an ear to snap off or crack. I check that each surface it perfectly flat and use a very thin gasket with a super thin old fashioned Permatex coating. You'll never brake a flange that way. I've seen a number of broken ears with thick gaskets. The same applies to the water outlet.
 
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