Kevin, what I am doing is welding the 2" o.d. pipe to the flange on the inside. This should be a 360 degree weld. Then use your die grinder to knock down the bead and make a smooth path for the exhaust gas. On the outside of the flange, just weld in three or four places (one inch long welds) to provide good structure, while at the same time allowing room for expansion and contraction. Jerry


On Thursday, January 6, 2005, at 01:08 PM, kevin lane wrote:

I decided to have my exhaust flanges recut to better match the ports.  Originally I simply had a 2" dia hole.  How important is it to match the shape of the ports, which is a collection of radiuses, straight sides, fillets and even a sort of non-tangential "fillet".  It appears that a 1 7/8" OD tube could be hammered to match this shape if I had it cut in the flange.  A 2" OD tube left round also looks like it would cover the port, but would leave edges where the straight edges of the port would dump into a round pipe.  These areas are very small.  My welder says that he routinely hammers exhaust pipes into "square" shapes, that the ports usually aren't round anyways.  He can stretch the pipe to a bigger dia., although I don't think that is a great idea, despite my using 1/16" wall 321 s/s.  I realize that I don't want the exhaust gas to collide with a smaller exhaust pipe shape, but what about a larger size?  Is it OK to spill into a slightly larger size?  Am I worrying too much about a small detail, or is this worth the time and effort?
Kevin Lane  Portland, OR
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