Thursday, March 12, 2015

Weld Mounting Flanges To first Exhaust Manifold Shell

 To help control the 18 degree upward tilt of the manifold I bolted some pieces of 1" angle to the side of the 1-1/2" angle base.  I then clamped on some pieces of wood with marks for where the center of the seam should line up to get the angle.  This way the shell can move if the welds are pulling it as they cool and I can see what is happening.  I don't think I could build my fixture rigid enough to hold everything without much heavier angle for the base.

I started welding by tacking all the corners (16 tacks). I started with the outer corners of each tube.  I did 2 corners at one end then moved to the opposite end and did 2 corners.  Then did 2 corners on the outer end of an inner tube followed by the outer end of the other inner tube.  Then I used the same pattern for the inner corners of each tube.  With all the corners tacked I then welded the top and bottom edges of the tubes to the flanges in the same pattern.

 This all worked fine and the shells held the 18 degree angle very precisely.  I found it easy to tip the vise to hold everything at convenient angles to weld the joints.

 The thing I hadn't thought enough about was the heat shields which are welded to the top to protect the valve springs.  On the next shell I'll try spot welding them on and possibly welding the edge completely before installing the flanges to weld.  I either had the edge too close to the flange and it was hard to get the puddle to form all the way to the bottom or the gap was too big and it was like welding two parts which just happened to be near each other.

The process I used for them was to clamp the shield to the shell, tack the corners, remove the clamp, and make the weld to the shell and the flange.

 With the welding done the top and bottom of the tubes, the seam on the manifold is still aligned with the marks, as it was at the start.

The top side was easier to weld because the heat box as not in the way but it had the added problem of the shields.

Once the top and bottom were welded the fixture was removed so there would be room to weld the sides without the nuts in the way.  This worked fine and the flanges are all still aligned and flat.

A complete manifold assembly.  The ends of the tubes need to be trimmed to the face of the flanges.  After that, sand blasting and paint, etc.

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