My New Engine—Tearing Down the Corvair

My new Corvair engine. This crankcase and the heads (actually, just one) will be
powering my Super Baby Great Lakes.

Bell housing off. A fifth bearing will be replacing this.

The crankshaft on top and camshaft on the bottom. The propeller will bolt onto the top shaft.

One of the two carburetors. My airplane engine will have only one carburetor and will be mounted below and to the rear of the engine, similar to a Continental or Lycoming.

Removing the engine oil apparatus (I don't know what it's called).

The alternator. My engine will use a John Deere alternator.

oil filler, etc.

Mike, holding the fan shroud. Check out the giant mice nest!

Magnesium fan and mice nest. I'm about to discover that mouse urine does major damage to aluminum.

Removing the harmonic balancer with a flywheel puller, $13 at Harbor Freight.

Again, the oil pump case (or something along those lines) on the rear of the crankcase.

The alternator. I'll send this in as a core and get a rebuilt one with points and electronic redundancy.

Having fun with my plane.

Pressure washing things. It didn't really help all that much.

After removing the fan and oil case cover. You can see the pistons, rods, and crankshaft in there. Cool stuff!

I convinced my wife to try out the impact wrench. She was nervous on the first one...

...but then thought it was cool. She did all the nuts on that cylinder head. I later learned that you're not supposed to use an impact wrench for this. Use penetrating oil and a hand tool so you don't apply too much torque and damage the case studs.

All twelve nuts off the case studs.

Push rods, rocker arms, and baffles.

Removing the cylinder head.

One of the baffling clips off and looking at the push rod tubes.

Head coming off.

Head off, push rod tubes coming out, cylinders awaiting removal. They slide right off.

The head and its combustion chambers. Each cylinder has a gasket right where Mike's finger is pointing, not a single gasket like most car engines.

Bottom of the engine with the oil pan removed.

This is the bottom of the half of the engine where the mice had their giant, cushy home. Notice all the corrosion?

I couldn't get this head off. I thought maybe the push rod tubes were stuck and so I cut them all in half.
That didn't help.

Tapping on the head wouldn't get it off, so I went ahead and undid all the rod caps and cracked the case. That left me with just the side of the case with the stuck head.

The camshaft.

The crankshaft, hydraulic lifters, and remaining case half, cylinders, and head.

This head was stuck big time. I ended up banging on the rod ends to try and use the pistons to drive the head off. One of my swings was off a bit and ended up hitting the crank case with the hammer. See next photo.

My damage to the case. I'm hoping this can be repaired.

Massive corrosion, clogging of the fins, and damaged fins. Damn mice. I'm sure this head is a write off. Hopefully I can just pay a core and get a rebuilt head without sending one in.

The culprit. This is why the head wouldn't come off. One of the case studs is essentially welded to the cylinder head. Another adjacent one is similar but not this bad.

To get the head off, I ended up cutting two case studs with a cutoff wheel on my angle grinder. Apparently, removing these from the case is a tricky job best left to a professional, or you risk damaging the case. I need to send my case halves to have them machined for three-liter pistons and fifth bearing anyway, so I have no motivation to mess with these.

First Wing Done!

Truth is I have a tiny bit of sanding left to do, but that shouldn't take more than a few minutes. I'm going to post a video summarizing some highlights about building this wing and a possible major piece of rework that I'll decide about after building the other three wings. I'll be starting on the upper left wing pronto. I'll be documenting that build with video, so there probably won't be any posts here for a while.

(By the way, the wing weighs about 21 pounds.)

Wing—Odds and Ends

There are lots of ways to skin a cat. After getting the leading edge wing tip pieces on, I discovered it needed a good bit of fairing. I wasn't sure how to proceed, so thought I would try an epoxy mix. I had oodles of the epoxy left from O'Reilly, so I mixed some West System colloidal silica filler into some of that. The back of the carton says that it's toward the strong/hard-to-sand end of the spectrum (there's only one more that's more difficult-to-sand/stronger). Well, turns out they weren't kidding. My arm almost fell off sanding that stuff.

So, I bought the 410 (last one on the right of the spectrum—easiest to sand). However, I didn't try that. I might try that one later. I ended up using something else I bought at the same time (from West Marine). It's in a caulking tube and is made for fairing. It's by Pettit Paints and is called EZ-Fair. I like it quite well. It's pretty easy to use and much easier to sand.

Some people also use Bondo and other people recommend Super Fil or Evercoat Quantum Filler. So, there are lots of choices. I'll probably try some of the others on the other three wingtips.

By the way, my fiberglass work is awful! I'm sure I'll get better at it the more I do it, though. Thankfully, you can slop more goo on it, do some more sanding, and cover up the first attempt.

This stuff was really hard to sand.

This carton contains the 410. It should be much easier to sand. I'll try it another time.

This stuff worked pretty well. Unfortunately, it's really expensive. Seems like all epoxies are quite expensive.

One end of the tube that will help to form the cutout in the center of the upper wing.

The other end of the tube that forms the center cutout of the upper wing.

Wing Tip Leading Edge

Making the wing tip leading edge was very challenging. The instructions were AWFUL!!! I read the paragraph many times and didn't understand it. Eventually, it began to make sense, but part of it never did become clear. Still, things worked out okay. Also, I have three more tries to perfect things. :)

 I made patterns out of poster board, then drew an outline onto the aluminum, cutting those out with tin snips. They were still a little big and so required a bit more trimming as we went.

Doing a little trimming with the Dremel. The wing tip leading edge pieces will get drilled and riveted to the piece attached to the leading edge you can see here. I cut the leading edge too short, which placed that little extension piece right over the rib. That made the leading edge stick out slightly due to its increased thickness. This is something I will definitetly get right on the other wings.

My friend Mike did a great job bending the wing tip leading edge pieces. I'll have him show me how to do it for the subsequent ones.

For the other wings, I'll have the leading edge longer as I mentioned above, thus keeping the leading edge from being thicker over the last rib (i.e., the piece of aluminum joining the leading edge and wing tip pieces will be outboard of the rib, not over it). Because of that, I don't think I'll need to put that vertical piece of fiber glass there on the other wings (the piece Mike is holding in this photo). I could be wrong, though, and might still want some fiberglass there to smooth things over. We'll see.

To hold the two wing tip leading edge pieces in place while we applied the fiberglass, we began by using some double sided tape under the metal. That didn't hold, so we applied thin strips of gaffer's tape. That was working okay until we clamped down the bottom of those pieces to the spar so they would hold that position while the epoxy cured. Then, the tops (leading edge) of those pieces pulled away a little bit. In a panic, I drilled a couple holes straight through the two pieces and put a couple screws through. After the epoxy cured, I removed the screws, then just put another layer of fiberglass over the first layer which covered up those holes just fine. Not sure what I'll do for the other ones. I'll have to think about it. This one turned out quite good, though.

We bought this fiberglass and epoxy just down the road at O'Reilly Auto Parts.

For some reason, there was space between the wing tip leading edge pieces and the spar, so I made a couple thin strips to take up that space. It turned out very nice. I epoxied them in place, then put nails through the aluminum and wood pieces into the spar. The nails and epoxy would have gone in anyway. I just added the wood filler to get a better shape with the aluminum.

The final fit of the aluminum wing tip leading edge on the spar. Very nice. Just needs a little dusting off.

A flapper disc (sand paper flaps on a wheel) made quick work of the epoxy. I also experimented with using different epoxy mixtures for fairing this area. I'll report on those later. I'm convinced (even though I'm still experimenting) that I would be MUCH better off using some softer materials (epoxies made for fairing) that sand more easily than epoxy mixtures that are so hard I need to use power tools to smooth them out. Also, I'm very inexperienced with composites, so I'm sure there are tricks to use to make this whole thing easier with better results and less work. Still, this first one is looking pretty darn good. Very nice, smooth curves.

Easy does it! Don't want to sand right through the aluminum!!!

Installing the Leading Edge

Installing the leading edge was tough! It took lots of fiddling to get it to fit just right, especially where the brackets poke through on the outboard end, and even then, I cut the openings too big. It'll be covered with fabric, so it doesn't really matter, though. And nailing took a long time. My back was killing me by the time I was done with that.

We scuffed up the areas where there would be contact with epoxy, for better adhesion. I put epoxy along the edges where I would be nailing, but I also epoxied along the very leading edge.

Trimming the end to length.

A view inside the wing with the leading edge on.

The final dry fit. We did probably more than a half dozen dry fits.

I'm applying epoxy here to the leading edge strip, the nail strips on the spar,
the butt rib, and the rib on the far outside.

I had also epoxied the aluminum angle pieces. This piece of spruce applied pressure to that area to keep that aluminum stringer snugly against the nose ribs while the epoxy cured.

My friend, Mike, thought of using this scrap piece of 2x2 to bend over the edges of the leading edge aluminum. You do this simply to remove an area of potentially abrasive contact of sharp metal on the fabric. Notice the straps. I bought these on Amazon pretty cheaply. I put one over each rib to help keep the leading edge tight while I nailed. I don't think I would use the kind with ratchets. You could pretty easily damage the ribs by over-tightening those straps. These worked fine.