Dave’s RV-7A Building Log

I finished drilling the transverse wiring holes through the seat ribs and started wiring up the strobe power supply.

I decided that I needed to drill some holes in the seat ribs. Vans has you drill some holes right next to the spar web. However, those holes are really not convenient for wiring. Instead, I used the location of the wiring conduit in the wings (also suggested by Vans) and transferred that to the side of the fuselage. I’ll basically have a transverse wiring run right at that location for strobe wiring and other misc stuff. I’m thinking about running most of the wing wiring and tubing through the outer-most holes in the spar and up the F-902 bulkhead. That would make much shorter runs than going up the center of the fuselage. We’ll see if that works out.

Anyway, I drilled half of the holes using a Unibit in an angle drill. It’s very difficult drilling in between the ribs. I wish I had drilled these earlier. It would be nice if Vans would make some better recommendations on wiring runs.

I also drilled a couple of #10 holes to use for the wiring tie downs. They are going to work out really well. The nice part about them is that I can use a cleco to hold wires in place temporarily.

Here’s a hot tip on wiring the stick grips: Don’t install the buttons in the grip until you’re sure it fits on the stick. It’s impossible to sand the inside after the fact. I was able to push out the push buttons from the inside with a long screwdriver. I pried the trim hat out with a putty knife. It actually wasn’t difficult at all.

I’m not sure if Michael makes the grips slightly undersized or the sticks are slightly oversized from the powder coating, but they need some sanding in order to fit. It’s not difficult, just time consuming. I wrapped some sand paper around a dowel and used that to sand the inside of the pilot grip. Julie suggested not doing this while the garage door is open as it looks very similar to another activity.

With the switches removed, I also decided to apply a tung oil finish as Michael suggested. The raw teak already looks very nice, but the oil does improve the finish of the stick somewhat.

After a long weekend out of town (the last for a while), I just tinkered a little bit today. I sanded the inside of the passenger stick grip until it would fit over the stick. I left it a fairly tight friction grip. I also put a coat of tung oil on the spare grip just to see how the finish turns out.

I flew out to Long Island, New York to attend Mattituck’s engine workshop. I was debating on whether the trip would be really worth it, but there was no question by the time the day was done. Mahlon, John, and crew put on a great workshop. I’m not ever planning to build up an engine myself, but the information I learned about all of the parts made me feel much more confident in the engine I purchased from them.

Here’s a shot of a pond that’s right across the street from Mattituck’s shop. And the tie-down area at the airport. It’s quite a scenic spot.

They held the workshop in a nice, large hangar.

Here are all of the parts that went into the TMX/O-360 engine (plus an extra crank and case to look at).

Here’s the tool chest with a bunch of special sauces for the assembly.

Mahlon started the show with some info and introductions. In front of him is the starting point, a bare crank with the nose seal already installed.

And here is the master builder, John. He demonstrated on the spare crank on the table how he installs the nose seal with a special tool. It took him all of about 2 seconds. In the picture he is installing the connecting rods. (Please excuse any incorrect engine terms, or feel free to correct me.)

Here are the case halves after some prep. The closer one has the silk threads installed in a thin bed of something I don’t remember. John described how they completed clean all of the parts, including removing the galley plugs and re-installing them.

Here he is installing the case halves with some assistance. He went into quite a bit of detail about how to make sure the case is correctly aligned with the bearing. He also did some measurements with a feeler gauge to make sure all of the thrust pressure between the case and crank is on the thrust surface and not on the “slinger.”

He tightened down a couple of bolts just to hold the halves in place.

Here the through-bolts are being installed with a hammer!! John used a special tool (a cylinder with threads in one end) to make sure the force of the blows is on the ends of the bolts and not on the threads.

The oil pressure regulator is installed here and the through-bolts have been temporarily tightened down to seat the case halves together.

Safetying of the regulator.

John next explained and installed the idler and tach gears. The lobe on the closer idler gear drives the fuel pump, so that gear has to be indexed correctly.

Time to put on the accessory housing.

“Darn I do nice work.” Or at least that’s what it looks like he’s saying.

It’s a little hard to see, but there’s a joint between the case halves and the rear accessory housing. The gasket is intentionally a little long at that point, so he trimmed it off. He also puts just a small dab of RTV on those spots before putting on the sump.

And here’s the sump going on. This engine happened to have a vertical induction sump.

The astute reader will notice something strange about the oil filter. First, it’s mounted on an oil filter adapter that makes it easier to access. With this adapter, you need to use a special oil filter that contains a check valve. The advantage is that hardly any oil leaks out during changes. The second thing that’s different is that there is an extension between the housing and the adapter. This is special for the RV-4 and RV-8 in order to clear the engine mount.

We breaked for lunch at this point–an excellent spread far exceeding what I would ever expect from a free workshop. When I got back from lunch, John had done a bunch of miscellaneous work including installing primer lines, dipstick tube, and a bunch of bolts.

John next prepped the cylinders and pistons for assembly. He worked from #1 to #4 at every step (even just moving the parts around).

Here is one of the pistons getting installed with its wrist pin. There is enough friction to hold the wrist pin in place, but just barely. The fuel pump was also installed right before this.

At this point, John used a special C-shaped contraption to hold the rings and wrist pin in place while he slipped the cylinder on.

This is a better shot of the gizmo being installed.

And the (I think) #4 cylinder going on.

Here John is installing the tubes that enclose the push rods (forgot the exact name). He used pliers on the inside of the tube to push them into place, seating the seals in the process.

After installing the rocker arms, he then moved on to installing the magnetos. This involved a lot of monkeying around with setting the timing correctly.

At this point, the main part of the assembly was complete. We all went on a tour of a great car collection at the airport and some other stuff. Meanwhile John finished up the last details on the engine. Here is the finished product from a few different views:

This is but a brief overview of the engine assembly. There were many more details about tolerances, torques, lubes, etc. explained during the workshop.

And now for the very best part of the workshop. Mahlon led us out to the test cell to watch an engine fire up. What d’ya know, it’s my engine!!! It had already been test run, but they fired it up again for a few minutes as a demonstration. Normally when they run the engines, they have a shroud over them for proper cooling. He left off the shroud so we could see it better, but didn’t run it for very long. It was most excellent and impressive to watch my engine run in the test cell.

One of the attendees of the workshop, Michael, had flown his RV-7A up from the D.C. area. He was kind enough to give a few of us RV-ers a tour of his plane after the workshop. It’s always inspirational to see a completed plane, especially one that is so nicely put together and finished.

I missed the tour of Mattituck’s workshop, but took a quick peek at their assembly room.

Overall, it was an excellent workshop. A big thanks to John, Mahlon, and the rest of the Mattituck staff for spending an unusually sunny and warm Saturday indoors explaining engine assembly to us. Setting up the workshop obviously took a lot of time from the parts prep, food & drinks provided, hand outs, certificates, and everything else. It was a real professional operation.

I soldered wires to the tabs of the trim hat. I used some of the Ray Allen 5-conductor servo wire. It’s really dumb that two of the wires are colored white, but I can easily figure them out with a multimeter and label them.

It took a little jockeying to get the trim hat into the grip, but it finally eased into place.

I’d have to say the grip is perfect.

The new pilot stick grip arrived from Mike Lewis. This one is left-handed with the push-to-talk button under the index finger. It truly fits my hand perfectly. It’s an amazing work of art.

I pulled out the soldering iron and started working on wiring up the buttons. After some trial and error, I discovered that I needed to solder the wires to the button terminals at an angle in order for the button to sit all the way down into the wood. They turned out great. Next up will be the 4-way trim hat. Oh how I love the smell of burning rosin. (The camera did its usual terrific job of focusing.)

And the most important news of the day: I learned that my engine was built up today. Woo hoo!!

I didn’t get much done on the project tonight. I spent most of my time “helping” Adele with her birthday presents.

I did print off and cut out some full size renditions of the instruments and avionics I’m considering for the panel. It looks very cool to have something on the panel, even if it’s just paper cut outs. The picture turned out fuzzy, but you get the idea. I’d like to make a little room for a Garmin 296 or 396.