Exhaust Manifold Inlet Flange - Cutting Ideas

 I have all the welding finished on the manifold shells.  It's time to make the inlet flanges which hold the manifold on the engine.  The ones on the old manifold seem to be 1/8" thick.  They also all bent, too thin and weak.  John made his 1/4" thick, which seems thick to me.  The WACO drawing shows them 3/16" thick.  I think with a slight redesign of the shape around the bolt holes I can make them strong enough to reduce the bending.  We'll get back to that in another post.  I've bought some mild steel bar stock 3/16" thick and 1 1/2" wide, perfect for our flanges.

 One of the problems making these is that they are mounted at an 18 degree angle, with the top angled away from the engine.  To make them fit properly on the manifold inlet tubes, the top and bottom of the rectangular hole are cut at this angle, not perpendicular to the face, like all the other edges.  I would love to know how the factory did it.  I assume they were stamped in a progressive die.

 My idea is to cut them with my spiffy Dillon Mk III (now Cobra Torches) oxy-acetylene torch.  In 20+ years I've never used the cutting attachment so this is a great chance to play with it.  The literature says it cuts better than a plasma cutter.  Like I ever believed that.  I set it up and practiced a bit with it to see how fast to move while cutting, etc.

I then clamped a piece of angle to my practice piece of 3/16" steel to use as a guide to simulate a fixture for guiding the angle of the torch cut.

 With the torch resting on the the angle I made a couple cuts across the steel.

I was shocked how clean and even the cuts were.  The band saw doesn't cut this well.  I need to build a fixture to use the torch to cut the flanges.