Snorkel Again, and Exhaust.

5 hours.

Today I did some more work on the snorkel, this time trying to shape the throttle body side to allow for smoother airflow, fill in some voids in the opening, and generally beef the thing up where the interface is.

This is looking into the relief hole I made for the alternator. You can see that the demoisturizer container serves as a perfect plug in place of the throttle body and the tape wrapped around it is exactly where the lip on the TB would be. The dark bit on the right inside the hole there is a void that didn’t get filled on the last glassing pass. I roughed up everything, cleaned it out, and went to town.

This is looking in from the top, where the air filter will go. It looks pretty anatomical, I know. The thing I have to fix now is where the opening bulges up, which will create a turbulent airflow.

Weapons of the trade. That’s the Builder Shield plastic on the left, and West System 206/105 epoxy resin on the right with the pumps sticking out. Living 3 miles from Marina Del Rey, I’m fortunate to have a West Marine store where I can buy this stuff. I wanted to get the 206 hardener, because I needed more pot life from the epoxy. I can wait the 10-15 hours for it to cure.

The photos stop for a bit, because of the whole resin/iPhone thing again. The next step was mixing up a bunch of micro to fill in some voids and take a crack at shaping a more gradual transition inside the snorkel where that burble was going to be. The first thing to figure out was how to fill in the voids around the actual opening itself. What I wound up doing was fairly genius (assuming it comes apart properly tomorrow). I wet down a strip of glass cloth, put it on the inside of the opening ring, then jammed the plug through it. It should form a perfect shape around the plug, and I can easily cut/sand off the excess on either side.

Here, it’s about done. There’s micro in there, and a couple of layups of glass around the burble and the rest of the edges go hold everything down. I also put a couple more layups on the outside to thicken up the interface ring.

With that curing, I went hunter-killer on some of the smaller items that I’ve been blowing off. First thing was reclocking the prop governor cable bracket.

This bracket also goes on the IO-540 in the RV-10, but the -7’s cowl doesn’t have enough clearance to let that happen. I’ve seen one or two examples of putting a bump in the cowl to allow the bracket to clear, but since I want to do as little fiberglass as possible, I decided to reclock the bracket. That just involves drilling two offset holes. The bracket will stay on just fine with two screws. I didn’t need to do much, that’s maybe a quarter-inch of distance between those hole, but I managed to bring the end of the arm down enough to where there won’t be any interference issues with either the cowl or the #2 injector line.

Since it’s time to think about things like control cable and wire routing, I decided I should probably put the exhaust system back on. The more things that are actually on the airplane, the fewer guesses I’ll have to take when deciding where to run things. Forward of the firewall, the name of the game is keeping things from picking up too much heat, and the primary source of that is the exhaust. The recommended distance between the exhaust and anything else is half an inch. Anything comes closer than that, and it needs to be shielded.

What you see here is the 4-pipe Vetterman exhaust I had to purchase to replace the crossover 4-into-2 type I had before. With the Crossover exhaust, there’s absolutely no way to get control cables to the throttle body without a horribly complex series of bellcranks and other things I really don’t want to mess with. The 4-pipe setup has a nice wide space up the middle where I can route the mixture and throttle cables without getting them too close to the pipes.

Since the right aft baffle is already on the engine, and finished enough to matter, I thought it might be a good idea to get the two-pipe cabin heat muff set up, along with the suspension by which the aft sections of the pipes hang. I’ll admit, I can’t find the instructions or drawings right now, but it really only makes sense to put it together one way. This is all about making sure I have all the parts, which I do, except one of the nuts is defective. There are no threads in it. I don’t even know what that type of fastener is called, to be honest, so I’m going to tap it for whatever threads the connecting rods between the brackets are. Like the crossover version, the pipes hang from stainless steel tubes connected by sections of rubber oil hose, so that’s no mystery. But with this and the baffle in place, I’ll be able to hook up the cabin heat system.

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