I mixed up some epoxy/flox and applied it to the mounting faces of the oil cooler plenum to fill in any imperfections and stiffen the flanges.  The oil cooler is covered with packing tape to prevent the epoxy from sticking.

I riveted the blast tube flanges on to the baffles along with some stainless steel mesh to keep out the bugs and debris.  This is the one on the front right baffles that sends cooling air to the alternator.

Here is the underside of this flange.  There is high-temp RTV between the flange and baffles to seal any air leaks.

I also riveted one of the left rear baffle to send cooling air to the magneto.

Here’s the back side of this flange.

Here’s where this fits in relation to the magneto.  This duct is obviously too long, but it shows the routing to the magneto.  I’ll anchor the other end with an adel clamp anchored to the upper oil line.

After trimming all of the baffles down an additional 1/8″, I laid out, drilled and riveted the #4 side baffle to the aft wall.  I dimpled the other flanges (the one with the clecos) so that the inside face will have flush rivets.  I’ll back rivet these, but it’s too late to run the rivet gun tonight.

I also riveted the #3 side baffle to the aft wall on the right side.  I also trimmed the bottom outside corner to clear the manifold pressure fitting.

Last night, I laid up some additional glass over the oil cooler plenum using the high-temperature epoxy.  You can see here that I wrapped the epoxy down the side of the oil cooler.  I also extended the circular flange forward another 1/2″ or so to make it easier to mount the butterfly valve.

For some reason, I didn’t remember until days after fabricating the first plenum that I didn’t use the high-temp epoxy that I bought.  I thought about just using it for the additional layers of the first plenum, but decided it wouldn’t be that much more work to just lay up an additional plenum.  This epoxy is definitely more brittle than West System epoxy.  I’m hoping it toughens up after adding a few more layers and post-curing it at high temperatures.