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.
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.
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.
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 trimmed the excess epoxy/flox mixture from the edges of the flanges and made the intake square to the opening and flat.
The flox mixture allowed the flanges to fit perfectly over the flange extension.
And filled in nicely where the flanges end. There will be some high-temp RTV between the mounting surfaces to seal any small openings.
I mixed up some epoxy with lightweight filler and buttered up the surface to smooth it out. This should be cured enough to sand by tomorrow.
I put a couple of skim coats of straight epoxy over the oil cooler plenum to seal the surface and fill the pinholes.
I put a couple of coats of paint on the oil cooler plenum. This is Cardinal Paint gloss gray that exactly matches the powder coat used on the engine mount. There are still some minor surface imperfections, so I may sand and reshoot one more time.
I installed the parking brake cable tonight. The cable comes pretty much straight back from the panel and then turns up and is anchored to one of the angles that support the VP-X (seen in the lower right of the photo). The cable then arcs across the cabin (anchored in the middle to forward top skin center rib).
The cable is then anchored to a piece of 0.063″ angle that is attached to the left subpanel rib. The angle serves as a mounting point for the cable as well as a stop for the parking brake arm. Here is the parking brake with the cable full forward which is the off position.
Here is the parking brake on the on position.
Here is how far out the parking brake knob comes with the parking brake on.
I drilled two additional holes in the firewall for the eyeball pass-throughs. The top hole is for the cable that will control the oil cooler butterfly valve. The lower hole is for the cable that will open the alt air port.
It’s pretty much a straight shot from the upper hole to the arm that will operate the butterfly valve (especially after I adjust the angle of the eyeball). I’m a little disappointed in these butterfly valve though. Aircraft Spruce specified this hole size for these cables, but the holes are a little oversized (they should be a few thousandths undersized so they securely clamp the cable). I’ll have to wrap some aluminum tape around the cable to tighten up the fit.
The lower cable will route behind the spark plug wires and be clamped to the oil return fittings.
On the other side of the firewall, it’s pretty much a straight shot from the panel to these holes. They’ll be anchored to the bottom of the subpanel and tied together in the middle. It looks like they’re about to touch the rudder pedal bars, but there will be roughly 1″ of clearance once everything is anchored.
I hooked up the alt air cable tonight. The cable is anchored to the oil return lines on both cylinders #2 and #4. I will have to replace the white silicone adel clamps with standard black rubber ones because the silicone ones can move around a little, but all this has to come apart when the panel is pulled out of the plane for painting/ labeling. You can also see that the aft end of the visible cable dips down and comes very close to the EGT probe. I’ll probably fashion a small bracket to keep the cable going straight back until aft of the baffles.
