Is the crack in the intake or the exhaust side? By the middle do you mean the upright part -- still same question, exhaust or intake end? I asked once, in dealing with a problem on another engine, about how much heat a brazed joint in a manifold could take and still hold, and never got a good answer. About all I could surmise is that for just ordinary gettin' around without a big load, you *might* get away with brazing on the exhaust side, or near it. But if you're gonna work the tractor hard EVER, you're apt to just burn it out and be back where you started. You may wind up with a replacement as the wisest choice, but also try to figure out how it cracked. (Somebody else chime in here if I'm wrong, please) On the As, Bs, and Cs, the manifold has cuts in between the ports where it faces up to the block. These cuts run right through the holes for the studs. And those studs have washers to go under the nuts. Only the studs at each end of the manifold are tightened down without these washers. This is so that the manifold, even when torqued down correctly, can expand and contract without breaking. Whatever your solution, patch or replace, if your manifold has these same cuts in it, make sure you've got those manifold washers in place when you put the nuts on it. It'll make for less stress on the braze and, if their absence was the cause of it cracking in the first place, perhaps prevent a repeat performance with a new manifold.
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