Posted by Vaughn [172.70.98.107] on Wednesday, December 15, 2021 at 18:54:29 :
In Reply to: Re: 251 exhaust manifold posted by rich nj [172.70.34.209] on Wednesday, December 15, 2021 at 15:05:46 :
No boiling required, you have to grind the thin layer of impurities off the cast iron before welding, the cast iron will appear shinny. Brazing works ok, be careful with nickle rod you want nickle that expands at the same rate as cast iron or it will crack again. My preference is to use 3/32 MG250 nickle rod on exhaust manifolds, no cracks recur again, very good rod, a little expensive, but it expands and contracts at the same rate as the cast iron. Depending where the crack is the metal can be a little thin so you have to proceed with caution. Your welder may not be familiar with MG rod, and if he or she can weld it ask some questions how they do it and what guarantee you get.