My exhaust flapper shaft has a lot of play in it, and is starting to leak exhaust fumes in to the cab. Is there supposed to be a bushing that goes there? Can this be fixed without buying another manifold? Some one told me to take it out and he would weld the old holes for $100.00, I told him if it was to get plugged I could tap it and plug it. But I know that's not the answer.
You can put bushings in the manifold to give a snug fit to the shaft and kits to do so may be offered by vintage parts suppliers. Be aware that the flapper is spotted to the shaft so it will have to have the spotwelds broken, usually by drilling. I aways remove everything to use a ream that passes through both holes so they are dead in line and don't bind the shaft. When re-assembling use stainless screws to re-attach the flapper if you don't have a way of spot welding the flapper back to the shaft. As far as welding the holes shut with the manifold off I'd take that 100 bill, weld them, and give you 90 bucks back. I absolutely know you can weld exhaust manifold cast iron with a mig welder with plain old wire in it so plugging two 3/8" holes would take all of two minutes or maybe five minutes if I had to grind it back to gray cast iron. Since your where the winters get cold I'd fix it if possible. Ford used a spacer that the coolant flowed through to heat their carb but I can't remember if they had a 1bbl unit. If so, spacing the carb mount studs to chevy dimensions and fabbing linkage would be easy.
