Paul.
  Can you have 4 flanges made also? Or 2 extra side plates I can cut
down for flanges.
Blake

The reason I choose 1/8th thick instead of 3/16th thick for the
front and back plates is I am going to simplify the design further.

I am going to TIG weld the 180 degree bend
two inch dia. .065 wall aluminum intake runners directly to the front plate and
two short two inch tubes .065 wall directly to the back plate. Much simpler to
attach the slide throttle carb system to the engine with a couple of short hoses
and four hose clamps. It is lower cost and there are no flange alignment
problems when you build the P-port rotor housings. Not to mention a
savings in nuts and bolts. Much quicker to take the slide throttle/carb
off and on as well.  Probably can be done  one tenth of the time. Not
to mention the time and cost of making the flanges.

The welding cost is the same.


Paul Lamar ...No rotor no motor.

Paul,
  I like the idea. Much easier to manufacture. I am not very
experienced with distortion from welding. Is that what the extra
thickness is for? Do you preheat the assembly before welding?
  Would you put a welded bead on the tubes to lock the hose
connections? Like a rolled bead but no internal distortion.

Blake

Yes that is the reason. Small local distortion can be sanded out
with a block sander. Large distortion will be taken out when
the front and back plates are bolted to the relatively stiff 3/8
thick center spacer.

Preheat won't hurt but is  probably unnecessary. One could tack
weld them in four places and forgo final welding as the cracks
could be sealed with JB Weld. A lot of rads are made that way.

I think the beads are also unnecessary as the manifold is always under
some vacuum. They won't hurt however.