Im doing a rebuild on my carb currently cleaning it, I found a crack upon inspection and I know I can use a marine epoxy to seal it up where the arrow is pointing at. I guess im asking if that crack is too much to salvage since fitting it on the base plate is very tight. I have another carb I can potentially use parts from… but the serial has no “A” between the 7 digit numbers and 2 letter code: 7028244 A KA - my original quadrajet 7028244 KA - old “new” quadrajet Anyone know what that A signifies or if their interchangeable float bowl- i think thats what its called? Thanks - Rob
Thats the welch plug that sits in a pocket. You can epoxy that area but I think you would be better off replacing it.
Pull those well plugs, thread the casting and insert threaded epoxies plugs. Then Build that crack up with epoxy. Other than that I would replace the body.
The reason the casting is split is because the original plugs were removed/replaced at some point and when they new ones were driven into the casting it split the material around them. From 1965 to 1968 the factory used pressed in brass "cup" plugs on the large ones and lead pressed in front plugs. The leak rate for those rear plugs is almost 100 percent, and pretty high on the front lead plugs as well. This issue gave the Q-jet a BAD reputation for leaking at those locations. In 1969 the factory corrected the leaking bottom plug problem by adding more material around the rear plugs and pressing solid aluminum plugs in place and swaging material over them. You still might find a leaker on occasion but it is quite rare and the later the carb was made the lower the chances of finding a leaking bottom plug front or rear. Even so every single blog, Forum, Youtube video, "builder" or "guru" or other source you get advice from will tell you to smear JB Weld (useless for this purpose right to start with) over bottom plugs on every single Quadrajet you are asking advice on. With no exceptions 100 percent of the early carbs repaired in this method fail a leak test when I get them on the bench here in the shop. The best repair for both front and rear leaking plugs is to remove the old plugs and tap the casting for screw in plugs coated with Marine Tex or a dedicated fuel resistant epoxy. The problem with 1965-1968 units is that many of them are "rotten" (the Carter built units will be the worst) and you will not be able to tap the casting without it crumbling away during the process. Any other attempt at sealing them up is hit and miss and from what I've seen here when they are already split like the one you have it's best to find another casting........FWIW.....
Ah I Gotchya thanks for the info. I’m starting a carb collection and so far I have a few carbs laying around, 71 for a 455 and another two 68s for a 350. Got my upgraded rebuilt kit from quadrajet power so I’m excited to start rebuilding them. Once done im just going to leave them plain jane no repaint but just cleaned nicely.
