Exhaust Manifold Shells On The Fixture

I left a little extra steel on the walls of the inlets to allow trimming them to a close fit. To trim them I made a small fixture which I clamp in the vise to work.  The fixture is made from a piece of 1"x 1/8" angle iron and some blocks of 1/2" x 1" bar stock.  I screwed the blocks to the angle so there is a 1 7/8" gap.  I also used some .063" steel to shim under them so the top is 9/16" from the angle.  That way I can place the inlet snugly in the tool and use the top of the blocks to scribe a trim line.

After trimming the square side to the correct height the radius right behind it needed tightening up.  With the inlet in the fixture I hammered down the cut edge behind it up to the wide flange.  It's subtle but it allows the pieces to all fit properly.

After hammering the tapered area I trimmed the steel to a nicer transition.

Everything fits nicely on the fixture.  The parts are finally looking like a manifold, very cool.

The next thing is to trim the flange at the outlet end so the 2 shells form a nice tube for the Outlet Elbow to fit over snugly.

I used the nibbler to cut down into the corner farther, then flattened the tab, and blued it to scribe a cut line.

I lined up a straight edge along the shell flange, scribed a cut line and trimmed it off with the snips.

I made a plug from a 2" pipe coupling to hold the ends of the shell.

The shell outlets are not perfectly round as formed.  I used the plug as a gauge and mandrel to adjust the ends to a nice fit.  You can see the small gaps in this one when first held to the plug.  It's easy to adjust it to a better fit.

With the shells on the fixture the plug is inserted in the outlet and the shells held tight to it with a tube strap clamp.  With this end held in position the shells can be clamped for welding.

Some day I need to find space to set up my nice Atlas 6" lathe for such projects.  That sounds like a good project for the grand kids in a couple years.

I used a 7" grinder with a 24 grit disc to take off the flanges on the pipe coupling.

A large socket was bolted to a board to allow the outside to be ground concentric with the inside.

You can see how the high spots are slowly being worked down.

I wanted the 2 ends to have different diameters so I could use one end to form the outlet of the manifold and the larger size to make the inlet of the elbow.  That seemed like a good idea at the time but I think it will be just as easy to assemble each elbow onto a manifold.

I reduced the diameter for the step by chucking the coupling on the Shop Smith sander drum and filing it to size.  The file is positioned so if it flies out it goes away from me.  You just lift the file to cut metal and slowly withdraw it so you don't just clog up one spot.