Dave’s RV-7A Building Log

Pop riveted the seals in place. The RTV didn’t hold so well. The seal material puckered between the rivets and lifted right off the RTV. Maybe I should have riveted them with the RTV not set up?? It won’t be a big deal. It seems like the seal will still push tightly against the baffle.

Worked on trimming the baffle seals to fit. I cut a few notches to allow the seal material to conform to the cowl and trimmed around the inlets a bit. The cowl seems to be sitting down pretty good. The process reminds me of trimming the baffles. It’s a lot of taking the cowl on and off and trimming.

Finished drilling the baffle seals. I read on one of the RV forums, that applying some RTV between the baffles and seals is a good idea. The seal material tends to pucker, so the RTV will hold it in place. We’ll see.

Julie helped me move the wings and stuff out of the guest room and back into the garage. Time to get the wings finished off and moved down to the hangar.

I decided it was time to drill the seals to the baffles. Not much to it. I laid out the holes on the baffles 1/2″ down from the edge, about 1-1/2″ between. I then clamped the seal material in place and drilled to #30.

I decided to leave a little more extra above the baffles for a total of about 2-1/4 inches. I marked on the material with a ball point pen and cut them out. Not too tricky.

I spent a bunch of time looking through the Mouser catalog for some better knobs, push button switches, and mini toggles. I also found the coax and Molex connectors that SteinAir sells. I’d rather get them from Mouser, plus they sell them cheaper. The coax connectors are Mouser part# 523-31-320-RFX. The Molex connectors can be found by searching for “Molex .084″. I was going to order the coax connectors from B&C, but they are now selling a genuine mil-spec connector that costs $5 each. The connectors that I’ve been using from SteinAir seem just fine and cost $1.33 in quantities of 10, which is how many I need. $13.30 sound much better than $50 for 10 connectors.

While I’m waiting for a few electrical parts from B&C, I decided to finish off the baffles. The only remaining task is to cut and install the rubber baffle seal material around the top. I looked all over for the baffle instructions, but I seem to have hidden them somewhere. I ended up cleaning up the workbench in the process, which isn’t a bad thing. If I remember right, the only thing they say about the seals is to install them. I don’t think there was much helpful information. I did some searching on the forums to find some advice. Leaving 2″ of material above the baffle walls is a good starting place. I’m going to try 1″ below.

I used some paper grocery bags to make templates, holding them up to the baffles, drawing a line, and then cutting them out. Looks like I’ll be able to use one strip for each side, front, back, and sides. I’m not sure if that’s a good idea. Getting the baffles off will be impossible without a break in the middle of each side where there’s a seam in the baffles. Time for more research.

Decided to install the seals I bought a long time ago from Aircraft Spruce. These seals allow the ignition wires to pass through the baffle. I could have used snap bushings, but these seals look cool and cover a larger area that will allow the wire to be installed/removed while keeping the bulky terminals intact.

The big drawback is that the seals have a really odd-shaped cut out. It took quite a while to figure out how to do it. In the end, it was fairly easy. Drill four holes in a line. The two outer ones get drilled to #10 for the AN3 bolts. The two inner ones get drilled out to 3/4″ each. I was worried about using the Unibit to enlarge the overlapping holes to 3/4″, but it ended up not being a problem. I just applied sideways pressure on the drill to keep the Unibit from catching in the overlapping area. I made a template out of stiff paper of the desired cut out shape and used that to draw an outline on the baffle. That helped quite a bit for coaxing the Unibit in the right direction. A little bit of filing to clean up, and they turned out great. Another item crossed off the list.

I spent a few hours while watching TV trying to figure out the innerconnects between the avionics. Talking to Carl down in NZ kind of confirmed my worries that Stark only hooks up what you tell him to. I’m figuring out what each line on each unit does and whether/where I want it connected to something else.

I started off my mixing another batch of epoxy. I decided to reinforce the ramp extensions I made previously. Before I laid up just 2 layers of fiberglass and it seemed a bit flimsy, especially since the baffle seal will be pushing against it. I laid up 3 strips on each side to reinforce the forward edge.

I then moved on to finishing up the riveting on the baffles. There were several rivets that I had to buck. A few aren’t very pretty, but they’ll hold just fine. I also drilled the holes in the bottom flanges that are safety wired together to wrap around the bottom of the cylinders. I also reamed all of the holes for screws 1/64″ larger per the instructions to allow for movement.

I then decided to mount the alternator. I’m not sure why I put this off so long. The parts have been sitting primed on my bench for weeks. I guess I was just concentrating on the baffles. Anyway I installed it.

I mounted the starter ring gear and estimated that I need an alternator belt 33″ inches long. Van’s suggests starting with a Gates 7350. I looked up that belt on www.rockauto.com, which states it is 35-5/8″ long. I’m not sure if that’s an inside or outside diameter, but I’m guessing it’s a bit too long. I’ll stop by the local auto parts store and see what’s available.

From there I figured it was time to install the baffles for the last time. It all went very smoothly, although I did manage to scrap a bit more paint off the rocker covers. I was hoping to be able to install the screw behind the dipstick, but I just couldn’t contort my fingers to get back there. I snapped a picture of the safety wire, cut it, removed the dip stick tube, installed the screw, and re-installed the dip stick tube.

Big day with some big accomplishments (as long as those stupid baffles don’t need to come off again).

Back from a few days in Green Valley (near Tucson) with my folks. It was good to see the sun again.

I worked a bit more on trimming the baffles to the ramps and the side ramp seals that I made. It looks pretty good. Hopefully that is the end of the baffle trimming.

I thought I was done with the baffle trimming a few weeks back, but I forgot about the ramps. I did several iterations of installing the top cowl, marking the baffles, removing the baffles, trimming on the band saw, and re-installing the baffles. The ramp extensions I made are working perfectly. I’ll probably add a few more strips of fiberglass along the exposed forward edges just to beef them up a bit.

The cowl is now to the point where it sits in the correct position again. I still need to trim a bit more to get a 3/8-1/2″ gap. Just a few more work sessions and I think I’ll have the baffles mostly done. I don’t know if it’s the nice weather we’ve been having or the prospect of moving past the baffles, but I’ve been enjoying the project more lately. It was getting to be quite a grind for the past month or so. Unfortunately, I won’t be able to put in any time for the next few days. And then I’ll really be driving hard to finish it up.

I worked more on riveting the baffles together. It’s slow going due to all of the weird angles. It’s very cool to finally be putting these things together. I can’t wait to install them on the engine for the last time.