Yup, I said it..... no, I can't speak german... thanks Google translate.....ha ha!
The Corvair authority William Wynne talks extensively on his blog about different carb applications in a Corvair conversion and the importance of keeping things simple.
The dual (and sometimes quad) factory Rochester carb setup on a Corvair car engine not only complicates matters (syncing throttles arms, etc) they were never designed for altitude compensation and mixture settings required in an aviation application. The converted Corvair engine falls into the same horsepower range roughly equivalent to typical medium Continentals and Lycomings, approximately 100 to 120HP. This requires a fuel delivery system capable of delivering an air to fuel ratio capable of supporting this demand.
Fuel injection? I believe the advantages (no carb icing, small increases in HP) are FAR outweighed by the complex system components (injectors, return fuel lines, pumps, electronics, sensors, etc). Keep it simple.
The MA3-SPA carb as found on the O-200 continental and O-235 Lycoming is the definition of simple. They haven't changed much since the 1940's and Marvel Schebler continues to make new ones today - in other words it works, simple. Overhauled to new specs it's the perfect carb for my conversion.
Finding one that is both inexpensive to obtain and overhaul becomes a problem due to this popularity. A good core for rebuild can be found in the three to four hundred dollar range then count on six to seven hundred dollars to overhaul it. Expensive, but not an area I want to save money on - engine reliability is important in flying! The recommended overhaul shop (D&G Supply in Michigan) also will convert specific O-300 carb models to the Corvair specifications.
Armed with this knowledge, I've been searching online for a suitable core.
A couple of weeks ago while surfing E-Bay, I came across a listing for an O-300 Marvel Schebler carburetor that would be suitable for my engine. It's clearly an older one, but again the model number matches the acceptable models for conversion and the pictures showed well.
Like anything on E-Bay, Kijiji or Craigslist it's a buyer beware mentality. One has to consider the odds and what it's going to cost to ship. In my case, the core I was interested in had no reserve pricing but the shipping costs weren't cheap - it was in Germany! This compounds the pricing with the Euro being somewhat strong against the Canadian dollar. Worth a shot.
With this in mind, I did the responsible thing and figured out my maximum bid would be about 100 Euros. I watched the days count down and was pleased to see my bid of 40 euros was enough to win! With shipping and currency conversion the total costs came to $112 Canadian. Not bad and certainly better than what I expected to pay for a core.
"Mein vergasser ist angekommen" (which means "my carb has arrived") on Friday and I picked it up at the post office yesterday. My first look had me really worried as the box had a crushed corner and was split open at the top:
There was a sticker on the box from Canada Post stating the box was damaged by the forwarding shipper. Not good. One of the fears shipping any item overseas or otherwise is theft. Hope there isn't just a bag of sand in here!
Opening the box, I smiled a bit finding a note from the seller:
Opening the box further, it came apparent that the shipper used a lot of bubble wrap to protect the carb on it's journey, but more importantly there is a carb inside the wrap!
It's definitely old, but everything seems intact and the throttle/mixture arms move freely. The accelerator pump seems seized but that's typical of something that has been sitting on a shelf for a long time and that will be repaired as part of the overhaul.
The data plate is intact and shows this is a model 10-4895 MS carb, typically used on O-300 engines. This is a good carb for overhaul and conversion to the required specs for my Corvair!
Glad I found this. It will be sent for overhaul this fall.
Back to the shop soon.
I made some excellent (small step) progress on my airplane build this past week.
Before I get into details, I want to share a bit of scrounging advice. Don't ever be afraid to ask around when you are looking for something, be it materials or tools.
While building, Ron and I often get to talking about ways to save on costs. One of the things that costs a bunch of money when getting it done by others is powder coating parts. Powder coating is a dry finishing process that gives various materials a durable coating that can be much tougher than paint alone. It's particularly good on non load bearing parts that may be handled regularly or exposed to friction. Control columns and rudder pedals come to mind.
Powder coatings are based on polymer resin systems, combined with curratives, pigments, and other additives and ground to a fine powder. A process called electrostatic spray deposition (ESD) is typically used to apply the resin to the metal substrate. The process uses a spray gun which applies an electrostatic charge to the powder particles which are attracted to the grounded part. After application of the powder coating, the parts enter a curing oven where, with the addition of heat, the coating chemically reacts to produce long molecular chains, resulting in high cross-link density.
That's the long way of saying "it sprays on and sticks really well after being cured in the oven".... ha!
Ron and I both figure the majority of the parts we might want powder coated should be able to be done ourselves. Ron has a source for the powder coating gun and resins, we just need an oven. Baking resins can generate a fair amount of unpleasant fumes, so we won't be using the kitchen!
I've been real fortunate over the course of the last few years to have several people I know come to me with leads on "airplane stuff" and I owe a bunch of that to talking to everyone I know about my project and plans. Opinions regarding my sanity range from "wow, that's cool" to "you are bat-s%$t crazy dude!" However, even if the vast majority consider me closer to the slightly crazy side of the scale, they do come to me when they hear of something.
In this case, when I mentioned that we were seeking an oven, Brenda noticed a Facebook post from a friend of a friend who was remodeling their kitchen. Turns out they were giving away a built in Jen-Air oven! Free! Brenda messaged them, I hopped in the truck and 10 minutes later, it was in our possession. We really don't need the stove top portion for baking parts so this is perfect:
We'll build a simple stand and wire it for power. It will require some calibration tests to ensure the temperature settings are accurate as they need to be for the powder coating. Not every oven is created equally as far as accuracy is concerned and oven temperature can drift as much as 25 to 50 degrees over time.
As for my airplane, I started to put the templates I made to use and traced out my first parts with them.
They worked real good. A thick Sharpie marker leaves a good line for rough cutting:
Before making the rough cuts of individual pieces from the sheet, now is the time to drill the corner relief holes where reuired. Here are some that I remembered to drill before cutting them out. Much easier to do this before hand I've learned!
Once the parts are rough cut out (thicker pieces on the bandsaw), further fine cuts are made using hand tools. By always leaving a bit of the thick marker line, we can see where the part will be trimmed down with the grinder, a file or hand sanding when taking of the burrs.
I made several parts over a couple of hours:
I took a good idea from Ron and taped the template to the parts when they were done. That way I don't have to write the part numbers on the aluminum. These completed parts will be stored until I need them later. I'm keeping a massive spreadsheet to track parts made, where they are stored and what inventory of materials I have on hand:
I know I have a TON of parts still to make, some simple, some complex.... but there is something so motivating about making these first parts for my 750 that makes me want to be in the shop full time. Unfortunately without spending at least some of my waking hours at my paying job, I can't afford the materials to make parts, so I guess I'll have to get back to the shop when I can.
Next up, further repairs to the 701 wing and I'll finish the sub assembly parts I need for the tail group on my 750!
Snuck over to the shop for a couple of hours Monday morning. I'm trying to squeeze in time when I can and a few hours in the morning before I head to bed for my afternoon pre-nightshift nap works perfectly.
Work continues on the 701 wing repair/rebuild. I managed to fabricate my first replacement piece, a rear wing channel. It took some time to figure out how to use the sheet metal bending brake, but I got it done. Here you can see the original bent and mangled one on the right and my new one on the left. The previous builder for some reason made his channel with a thinner gauge of material than what the plans call for. I'm all for saving weight and money, but this is a critical structural component, not something I would consider worth skimping on:
Next was removal of the damaged nose skin. As part of the repair/rebuild, Ron is planning on extending the wing by a couple of feet. We'll cut out the damage, fabricate a tip extension to the main wing spar and add a rib where required. A new nose skin and upper/lower wing skins and will be cut and fastened to the originals. Of course, this means drilling out more rivets. I suspect there will be times this will come in handy when I make mistakes on my own build!
This picture shows the extent of damage. What do you think..... is this creased too far to be "popped out"?
I drilled out the rivets on the closest good rib to allow some flexibility when cutting the bad nose skin. We'll trim it cleanly back to the rib to enable a clean joint with the new extended skin. These empty holes will become part of the stronger joint as a result.
As always, I'm keeping my eyes open for good deals on things I need for my project. Surfing the classifieds section of the Ultralight Pilots Assocication website, I came across an individual selling a complete rudder section for a CH750 for an amazing price that was too good to be true! A quick game of phone tag and the seller and I agreed to meet on Friday this week.
On the road again..... can't wait to get on the road again.....
Previously on part one.....
Without the resistance of the blower fan and suction of the vacuum filter assembly, this motor spins way faster than what the label states. So fast in fact it wants to tear itself apart while merrily dancing across the shop floor despite being mounted on springs (or maybe because it's mounted on springs?)
So, I need to figure out a way to slow the motor down or reduce the vibration component.
My first thought is to reduce the size of or modify the shape of the metal strip I added to the motor axle.
I think doing this only reduces the vibration. The motor will still be spinning way too fast and determining the right size of strip may be hit and miss to get exactly right.
How about controlling the motor speed? I think this will be the easier route.
Digging through my box of household electrical stuff, I found two incandescent dimmer switches that should work. They are designed for AC power (as is the electric motor) and this would add the ability to fine tune the vibratory effect for best results.
Before that however, I need to finish creating the parts bowl. First I inverted the bowl and traced a circle on a piece of spare lucite (plexiglass):
Cut the circle out using my bandsaw...... that's when I realized the centre section of the bowl sits above the rim:
To secure the new lid, I used a piece of hollow threaded rod. I screwed it into the top plate of the tumbler and l left it long enough to add a cap to hold it down tight to the bowl:
To hold the lid, I found an old powder scoop that fits perfectly over the bowl centre. That and a washer and nut hold everything down nicely:
Now that everything is built, back to slowing down the motor.
I added in the rotary dimmer switch. It has an off position when turned counter-clockwise all the way. I'll tide up the wiring once I figure out if this is going to work as designed. The picture was taken prior to creating the lid. Using the dimmer works!
Time to test the machine....
First, add the tumbling media, in this case a couple of scoops of clean clay cat litter. Then add some dirty, greasy and rusty test parts:
Close and fasten the lid..... all secure and "go for power-up!" The vibrating of the tumbler makes it hard to get a clear picture, but the media very quickly envelops the parts. As it tumbles, they occasionally come back up the top:
The tumbler is NOISY! I suspect the bolts between the levels of the tumbler are vibrating against the bowl. That should be easy to fix. Perhaps it might have to be run outside. After letting it run for about five minutes, I decided to have a look at the progress. Even after only 5 minutes, the parts are obviously cleaner and devoid of the grime they entered with:
Although the parts come out a bit dusty, clearly this method and machine I've built works very well, even at a short duration. I'm planning on running a longer test this afternoon and will post more details.
So as I mentioned previously, I have a pail full of loose hardware (bolts, nuts, washers etc.) that are completely covered in dirt, grime and rust. I pondered using my daughter's rotary rock tumbler, but learned that the interior of the drum can get destroyed by the tumbling medium and the metal parts.
A quick Google search led me to this post on how to make a Vibratory Tumbler:
The tumbler described in the link above is for rocks, but the concept is simple enough, perhaps I can come up with something for cleaning my parts. Another Google search led me to this You-Tube video:
Now that seems more like the type of task I'm trying to accomplish! And the cleaning media is cat litter!
Shouldn't get much cheaper and easier than that! Let's build one!
First, I obtained the following two items from the Value Village thrift store:
I tested the vacuum in the store before purchasing it to make sure it worked. It was missing the nozzle extension, so as a vacuum it really was worthless..... but it's the 9000 rpm electric motor that's inside I'm after. Recycling at it's best!
Remove the filter section and split the main case open:
Remove the motor/blower assembly and filter gasket:
Pry off the outer housing with a small screwdriver and remove the blower fan:
I removed the plastic backing plate leaving just the motor assembly. The mounting screws are quite short so I needed a thin board to mount the motor to. I had an old poly cutting board (white one on the bottom of the picture below) that I wasn't using for anything. I drilled out a large hole in it for the motor axle and two smaller holes for the mounting screws. The upper board is where the bowl will sit, for this I used a piece of scrap laminate flooring I had kicking around. I used 6 inch bolts with lock washers and nuts to space them apart enough to fit the motor in between. This whole assembly will be the vibratory part:
Next, I mounted the vibratory assembly on compression springs I bought in the surplus aisle at Princess Auto. Then the whole thing is mounted on a base of wood:
Next I mounted the motor. In the vacuum, it was designed to spin at high speed and very smoothly.
In my application, I want the motor to continue to spin at a high speed, but to also vibrate at high frequency. To accomplish this, I attached a small strip of scrap metal to the fan mounting bolt/axle of the electric motor:
So... thinking all was good, I figured it was time to test it. I very quickly learned that the motor was designed to power the blower fan with the added resistance of trying to move the air through the vacuum filter. Although I did plug in the motor and tested it once I had it outside of the vacuum housing and disconnected from the blower I didn't think much of it. However, without this resistance, I believe the motor spins much MUCH faster than it's rated RPM. Adding the attached metal strip and the whole assembly almost jumped and bounced across the shop floor base and all when I applied power. I should have tested this before mounting it, but it probably would have ripped my hand off in the process.
This obviously won't do.
More to think about..... stay tuned for part two.
So here is a first look at some of the highlights of my find.
There are a LOT of parts to go through and inventory, but I can't begin to explain how stoked I am about my acquisitions.
Most of everything is either salvageable as is, prime for exchange as a core for re-manufacture, or trade-worthy for other things I will need.
Casting numbers (T1208RH) on the dis-assembled core block indicate a 1965/66/67 110HP "automatic transmission no smog" block manufactured on December 8th in either 1965, 66 or 67.
The casting numbers (3878566) on the heads from this core indicate 110HP from 65, 66 or 67.
These are prime candidates for conversion. Two things I haven't found in the boxes yet are the camshaft (but that isn't a game-stopper as it will be replaced by a custom cam anyhow) and the push-rod tubes (cheap to purchase new). Everything else important seems to be there.
The original cylinders, pistons and rods from this 110hp core are in great shape and will be excellent core exchanges.
The crankshaft is the correct model (8409 cast iron) for conversion. It has already (as far as I can tell and was told) been drilled for the prop hub and safety shaft. I'm not sure if it has been nitrided or not, should be easy to find out. Huge savings having this already complete.
The new in box pistons I got with this lot have been superseded in the latest conversion plans with dished and forged aluminum pistons. Perhaps these can be traded or sold.
I paid a bit extra to obtain the prop hub assembly. It includes the machined safety shaft called for in the conversion plans. A new one from William Wynne costs over $500USD, I got it for $50CAD. Great deal!
The second core is still almost completely assembled and appears on the outside to be super clean. The valve covers even have some of their factory chrome finish left on them. The cooling fins are real nice and straight on both the cylinders and the heads.
Casting numbers (T1214RM) on the dis-assembled core block indicate a 1965 or 66 140HP "manual transmission no smog" block manufactured on December 14th in either 1965 or 66. It would be neat to know if both this and the other 110HP block were made within 6 days of each other!
The casting numbers (3878570) on the heads from this core indicate 140HP from 65 or 66.
This block is also a prime candidate for conversion. The heads however would have to be directly replaced with 95HP or 110HP heads. They will be of value to someone, probably a car rebuilder (140HP heads are rare). Of course the crank and camshaft are still inside and the push-rod tubes are there as well. I haven't looked inside this motor yet Everything else important seems to be there on this core too.
Although not pictured, Paul also included new in the box set of chrome piston rings and a David Clark headset (which appears new from the box!).
So, I think it's fair to say I've got a running head start on my engine project. A complete inventory is next. Time to buy some storage totes :)
On another note, I'd be remiss in not mentioning the support for this mission that has been given to me by my wife Brenda. She always seems to guide me away from to good to be true deals to hidden ones like these. Thanks - I love you.
Well... I made it to 46 years old. How I did that and didn't end up in jail, dead or otherwise is anyone's guess.
A couple of important updates to report that happened to coincide with my birthday.
First, I think I might have finally found a core engine. In fact, I might have found TWO! I responded to an ad on Kijiji posted by a guy in southern Ontario and spoke with him this evening.
Best part? These cores were destined to go into a couple of Pietenpol Aircamper projects he was involved in so they "should" be the right type!!
I'm heading down this weekend to have a look.
Also tonight, I ordered the William Wynne Corvair disassembly DVD which guides builders towards taking apart a core and what trouble areas to look out for.
All in all a great way to spend my birthday!
Decided to go for a drive yesterday and have a look at that core engine that I missed seeing last week due to weather. Also did some shopping for workshop stuff and had lunch with my dad Jim and Barry's wife Linda.
In the afternoon, I finally made it to the home of the guy I've been speaking with on the phone on and off for a month or so. Ed is a salt of the earth retired gentleman, looking to clean out his collection of "anything mechanical" as he calls it. He is a retired machinist and tinkerer with a focus on antique tractors and building working models of late 19th / early 20th century internal combustion engines. A quick look around his barn (it was kinda dark in there) shows both his attention to unique and rare items and also lots of discarded stuff he picked up at junk sales and auctions. Unfortunately, a good bunch of it never made it to the restoration phase and now he just wants to start clearing it out. It's kind of like the places Mike and Frank from American Pickers love to go digging in.
Climbing up an old wooden ladder into the loft, Ed leads me to a corner of the upper barn floor where he uncovers the Corvair engine we've been chatting about.
Cut right from the donor car it came from, it sits still attached to it's transmission and motor mounts. Everything appears to be there, but my first glance tells me this is probably at best a 1964 model, but likely 1963 or earlier. I can tell by the generator mounted on the top front corner. GM started to replace generators with modern alternators around this time, so it's still possibly a 1964.
One of the issues that made me want to attend in person to see this core was that Ed is not online or using e-mail, so describing where to find the casting numbers verbally is an issue. He did have a look, but the only number he found was the cylinder firing order stamped on the cooling shroud. This is the same for all Corvairs regardless of year, so not much to tell from that.
Scraping under the requisite dirt and grime, we found the engine casting number:
T = Tonawanda
12 = December
18 = 18th day of December
YN = many possible blocks (damn)
According to my manual, YN engine block code was a commonly used code meaning the engine could be from 1961, 1962, 1963 or 1964. It gets even more clouded as the 1960-1963 engines were either 140 or 145 cubic inch engines. From 1964 onwards the displacement was 164 cubic inches (the block I need) but the 1964 engines have smaller head gaskets making them less suitable for conversion than later versions. Some 164 cubic inch engines were rated at 95 hp and do not have the harmonic balancer (torsional vibration dampener, also needed for the conversion). This doesn't account for cars built towards the end of 1963 that might have 1964 generation motors in them.
Although it is possible to use a 1964 block, it's not ideal.
Okay, what about the heads? Are they usable? Don't know until we check the casting numbers. Which for some reason don't exist!
I started by cleaning off the crud with brake cleaner and then used light application of a wire brush.
I don't know if the casting numbers are missing from the heads, or perhaps they've corroded away completely but they aren't visible, even with a good light source. The one in the left picture (above) doesn't seem that badly corroded to obliterate the casting numbers, but I'll be damned if I can find them anywhere.
Another oddity is a stamped number "3" that appears to have put there sometime after leaving the production line.
So this just deepens the mystery of what exactly this motor is.
I borrowed a 1/2 inch drive extension (something I need to add to my "go-kit") and tried to turn over the engine using the front pulley bolt. Solid as a rock (didn't expect it would turn).
Peeking through the cooling shroud, the fins of the heads seem clean enough, but you can't tell anything from a little peek. The rest of the engine shrouding and valve covers seem pretty roached.
I think I might offer to purchase the whole thing for scrap value alone to use as a practice engine to disassemble. Perhaps there might be some value in that or some of the internal components I can trade with or send in for core exchange.
The quest continues..... <sigh>
I'm going next week to look at a core engine that is for sale.
The older gentleman who is selling it can't recall what year chassis it came from and by extension what generation engine it is. I've given him verbal instructions on where to locate the block and head casting numbers, but he says the only number he can find it the firing order stamped on the shroud. Not sure what more instruction I can give him as he doesn't have email to send him an example picture. I think it's a combination of not understanding where to look and not understanding what I'm looking for.
Now, I know a couple things (or at least I think I do). The firing order is the same for all Corvair motors as they came from the factory regardless of year, so that won't tell me anything. I know from the shop manual what the firing order is.
What I can't find anywhere in the conversion manual or shop manual is where exactly the firing order would be stamped on the shrouds.
So, my questions become this.... where exactly is the firing order stamped on the shroud (or elsewhere on the engine) AND was this stamping done for specific model engines only (is that a clue to what generation it might actually be?)
E-mail sent to the Corvair Jedi, William Wynne.
I'm still going to see the motor as I have other means to figure it out and I'm right in the same town for work meetings next week anyhow.
Also have another lead for a core engine.... waiting on answers for that one too.
In the meantime as part of my shop clean-up, I've assembled a "go kit" for evaluating any engines that I get to see in person:
I can feel the force working :)
As I continue to read and digest the information in my conversion manual, the more I realize I've got a ton to learn. But that's what I'm here for (see Motivation).
One of the main items that the conversion manual refers to is the original General Motors (parent of Chevrolet) "green shop manual". This is the manual issued to dealer service centres and covers pretty much everything bumper to bumper on how to service and repair a Chevrolet Corvair. It contains bolt sizes, torque values and disassembly / assembly procedures.
Of course for my project, I'm interested in the sections of the shop manual that apply specifically to the engine assembly and perhaps some of the chassis stuff where the engine is attached. This will be a huge help if I obtain an engine still in a chassis or attached to a transmission.
I did some research online and these manuals are actually still available from Corvair parts suppliers and on EBay.
Further Googling (if that's a word) led me to a PDF copy.
Print, punch and put in a binder. Not green like the original but perfect otherwise! More reference material for the build in my shop.
Time until takeoff
Husband, father and 911 dispatcher. Long time pilot with a licence that burns a hole in my pocket where my student loan money used to be. First time aircraft builder. Looking to fly my own airplane.