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Well, after trying many gaskets and o-rings, and after speaking with Mike at Mike's Carburetors, I thought I had the fix to my leaky plug on top of the carb. He suggested that I file the mating surface on the carb and the brass plug, which I did, and this led me to the discovery that the plug was cross-threaded. I don't remember doing it- but I could have. Looks like a 5/8"-20 thread, but I don't think I can fix it.

Anyone have a spare carb top for a "48 Super Eight Carter carb?

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I'm sure you'll be able to find another casting, but have you considered a thread repair kit?

Just as a caution to readers, another thread on carburetors that often found stripped is the accelerator pump pivot shaft on some prewar Strombergs - it's a LEFT-HAND thread to prevent the pivot from unscrewing with repeated use.

I've been thinking about a thread repair kit. Amazon?

I guess you can buy almost anything from Amazon but in the absence of a local machine shop supply company I'd be inclined to try places like MSC Industrial Supply, or McMaster-Carr who specialize in machine shop and industrial commodities.

Good call. There's an MSC nearby in Pompano Beach.

5/8-20 is kind of a special thread so I would wonder how readily available a repair kit would be. Also, is there enough meat on the carb body to drill and tap oversize for the insert? Is there any kind of specialized repair pieces at a carb shop who routinely deal with this kind of situation?

Is there a chance you could get a 5/8-20 tap and rethread your existing. There are several places where you can get those taps although for a one time use, at $16.50 this is one of the least expensive. McMaster sells the same size for close to $50 although it is probably a better brand.http://www.victornet.com/subdepartments/Special-Pitch-Taps-9/16-to-1-1/8-inch/1270.html If you went with Victor they do have a minimum $25 order so you would need to buy something else to bring the total up.

If you can rethread and if the plug is slightly loose afterwards and doesn't seal even with a new fiber washer, Amazon and other places sell a teflon paste pipe sealant which is gasoline resistant and could be applied sparingly to the plug..

Yes, the MSC kits are pricey. I'm not exactly sure if that's the correct size- I used a thread gauge and it definitely shows 20, but the size may not be 5/8" as it fits loosely in the 5/8" hole on my plastic gauge.

It may be 9/16"-20 or 19/32"-20.

Once you figure the exact size they probably have a tap. I have bought several from them in duplicating some of the Packard switch and instrument panel threads but those turned out to be mostly standard but obsolete electrical sizes. That is one nice thing about Victor. If they do not have a special thread tap they can make it.

Have you tried non hardening Permatex and a new fiber washer or maybe even a gasoline rated O ring or are the threads so bad the plug just won't tighten?

I tried an O-ring, and it worked for a while. Must not have been gasoline rated. That would be the cheapest solution, as the plug still tightens nicely.

what about a copper o-ring/gasket