Does anyone know of a source for weld on outlets for an original exhaust manifold?
I cut the flange off a broken exhaust manifold and graft it onto an original manifold with the factory heat riser. There also needs to be a slit cut into the original manifold with a cutoff wheel on an angle grinder to install a baffle just ahead of the heat riser to split the exhaust stream between the two flanges. Leave 1/4" or so gap at the top of the passageway to allow for pressure equalizing instead of doing a full blockage. As always, preheat, peen, post heat, and bury the modified manifold in a pile of sand overnight to prevent cracks beside the welds as it cools. It's also a good idea to keep the manifold bolted to a junk cylinder head when welding to avoid warping the assembly. Use nickel-alloy arc welding rod.
Jerry
