Hi,
is there any DIY way to reduce the TIG welding stresses between runners and flanges in an exhaust manifold?
Is heating at a sub-optimal temp and cool down going to get somehow the stress lower?
I made a jig to hold mine whilst being welded but the welder didn't think it was necessary and took it out of the jig to weld it. Also didn't use the bottle of purge gas I supplied so got it full of sugaring too but that's another issue
(this was all before I got myself set up with a decent TIG BTW).
Anyhow, the centre two runners were probably 10mm out of line with the outer two. I used a oxy torch to heat them and bend them into line. The flange was also bowed like a banana and I filed it flat.
If I did this again I would first weld the collector together onto the flange because that's where the most of the movement is generated, instead of fitting the whole lot up and welding. Then I'd flatten the flange, stick it in a jig and cut the runners. Just welding the runners to the collector should cause very little movement.