An 8-tube motor mount on the front end of Dave The Bear's Wagabond, above. This motor mount style is my preferred design when the datum to firewall distance exceeds 15". Weight and balance calculations placed this distance on Dave's mount at 17.5". For comparison, a 601 is 14.5" and a KR-2 is 10.5". The Skycoupe has been flying for years on our first 8-tube motor mount. Its datum to firewall distance is about 16.5".
Above is the proper orientation of the motor mount hardware. The bolt is an AN6-35 with a castelated nut and a cotter pin. The Energy Suspension urethane swaybar bushings are available from Summit. The length of the bolt is appropriate for any mount or tray built by us or built to the plans in the Manual. The nut should be tightened until the bushing expands to the same diameter as the plated washers that come with the bushing kit. We use a piece of 3/8 i.d. tygon tubing about a half inch long around the bolt where it passes through the case to align it. When assembled, the engine will seem very tight to the mount. In operation it will perform flawlessly. At the recent Livermore, Calif., fly-in, a video was shot of a Corvair engine running on the ground. Its excessive motion was caused by the bushings not being tight, and primarily by the engine running very poorly because the condensers were rigged on the wrong sides of the coils. Properly installed and wired engines run smoother than most aircraft powerplants you've ever seen. Motor Mounts we sell now come complete with all the bushings and hardware.
Above is a first class fiberglass reinforcement for the motor mount, inside a Corvair powered Dragonfly. It is patterned after the same style mount in a Lancair 320. The Dragonfly is an all composite airplane, with fairly light mounting points designed for VW powerplants. If you're installing a Corvair on one, you should seriously consider this style of load bearing structure. This applies only to designs like the Dragonfly and the Vision.
We brought the Turbo Skycoupe into the hangar for a cowling change. I removed the old cowling and put all the sharp PK screws in a plastic shoebox on top of the wing. Whobiscat promptly settled in for a six hour nap, above.
Dave's oil filter housing, above. This is the recommended installation for any airplane with a gravity feed fuel system. Airplanes that use fuel pumps will have a slightly different variation. The oil filter is a K&N 1002; the housing is a Transdapt 1045; the line fittings are AN-6 to 1/2" pipe, made by Aeroquip. The pressure bushing is also Aeroquip, 1/2" to 1/8" pipe. The oil lines are Earl's 90 degree -6 swivel seals. All of this is from SR. This installation shows my preference for mechanical oil pressure and oil temperature gauges. The temp gauge sending unit will thread right into the housing. The little clamp on the line is a No. 3 Adel, from AC.
Dave's airplane uses a Stromberg NAS-3 carb from a C-85, an excellent choice for a gravity feed airplane. 85 and 90hp versions of this carb have a 1 3/8" venturi. The fuel line shown above is a 180 Earl's swivel seal -6 from SR. Note the simple cable hookups. AC also has carb to manifold gaskets. Just order one for a Cessna 150. The hardware holding the carb to the manifold is AN4 with NAS reduced size, all metal locknuts.
A top view of Dave's carb installation, above. The manifold is one of our CNC bent stainless tubes. Note that the only joint in it is where the carb tube is welded. Dave made this carb tube from a 2" piece of .049 4130. Thus, it's painted to prevent it from corroding, while the rest of the manifold is bare. The main mount for the manifold is the plate above the carb, which grabs the two lower 3/8" studs on the engine case. I greatly prefer the carb to move with the engine at all times. Carburetors mounted on the engine mount and connected to the intake manifold with rubber hose are an invitation for trouble. The one and only certified airplane that mounts a carb that way are certain Mooney models. There's a good reason every other plane has its carb move with the engine. The two braided -6 lines in the foreground are on their way to the oil filter housing.
Dave's MSD 8210 coil switcher, IC-675 coils, and gascolator are all mounted in a box on the firewall which will be fed cooling air through a 1 1/4" scat hose. The two side walls of the box are riveted on the firewall, and the cover is removable with PK screws going through Tinnerman nuts. The IC-675 coils are available from NAPA. They do not require a ballast resistor. Recent testing by Gus and myself reveals that these coils will power your engine at voltages down to 9.6. Thus, if your generator was offline, your motor could run off the battery that started the engine for a long, long time. The bracket holding the two coils is a C shape. They're held in place by the wedge block and angle clamping them down with an AN3 nut in between the two coils. This plane needs a primer because the Stromberg carb does not have an accelerator pump. The primer pump works off the fitting on top of the gascolator.
The above photo shows Dave's carb heat box/air filter arrangement. This is referred to as a J-3 airbox, although it appeared on most light aircraft with small Continental engines. It bolts right onto a Stromberg or MA3 carb. New ones are available from AC. Used ones should be inspected carefully because the shaft bushings are usually shot. A 2" carb heat hose connects to the side, and the front face mounts a Bracket air filter assembly. This is the easiest way to mount carb heat and an air filter on a Corvair engine. In this photo, also note the two Adel clamps holding the -6 fuel line. All motion on the fuel line will take place between this clamp and the 180 degree fitting. You can see the finger reinforcements welded on the bottom tubes of the mount, and the 1/8" pipe primer port welded into the 2" intake pipe at a 45 degree angle. The gascolator and carb on this aircraft are above the level of the bottom longeron. You want to be sure that if you ever wipe the gear off the plane, you're not going to open up the fuel system.
Dave's ultra simple panel. It is cut from a sheet of .060 6061 T6 aluminum. The lower knobs, left to right above: primer, carb heat with lock button, large throttle with knurled lock, vernier mixture. These are all different sizes and shapes so they can be differentiated by feel. A big mistake in installations is builders putting in a throttle and mixture of the same style but different colors. When you reach for them, your hand is going to i.d. it, not your eye checking the color, especially on landing approach. These cables are available from AC. Resist using lawnmower cables because they do not have quality operation nor locking features. Dave's airplane is essentially brand new and first class, yet he has only $8,000 in it, including the engine. This is because Dave is a good scrounger, but notice he didn't waste money on things like worthless electronic engine instrumentation, nor expensive radios. The point is to get the airplane flying now and add the radios later when and if they prove necessary. Complicated panels are the biggest waste of money in airplanes, and if you choose to delay the completion of your project because you're saving for avionics, I will assure you that you won't consider that a wise choice that day in the future when you lose your medical.
Dave's plane will be outfitted with a 601 nosebowl. Here, we borrowed the one from the 601 for a test fit. The plywood ring on the front holds the nosebowl in place and centered. It's an installation tool we use that could easily be duplicated in your shop.
The throttle, carb heat and mixture cables coming through Dave's firewall, above. The blue AN collet style cable clamps are available from AC. The throttle cable exits the firewall at a 45 degree angle. We fabricated the bracket from a piece of 1 1/4" 4130 tubing with a washer welded on the end. The throttle on the panel and the carb line up with each other perfectly, and this aircraft has very slick throttle operation.
This is the MSD to distributor cap high tension wire. It passes through the firewall box lid, runs along the upper motor mount tube, jumps across to the intake manifold and goes on to the distributor cap. It is Accel spiral wound wire. We've flown this style of wire for years, and have never noticed any radio interference, despite the fact they have very low resistance. Notice that there's a grommet where it passes through the box top. This grommet lines up with a very heavy duty piece of heat shrink. This heat shrink is made by HILINE. HILINE electrical products are available either direct from HILINE or from a number of distributors. Their heat shrink tubing is the world's greatest. Two Adel clamps hold the line rigid to the mount. A -12 goes around the 3/4 mount tubing and a -6 goes around the plug wire. Note the heat shrink under the -6. They're held together with a 10-32 screw and an all metal locknut. Proper security on this line is crucial because if it falls off, the engine won't run. You can have a plug wire or one of your coil to MSD lines fall off, but not this one. I'm against having your alternator on the back of the engine because if the alternator belt falls off, it could take this line out. If this seems unlikely to you, consider that my friend John Blackburn was killed within sight of his own house by exactly this event in his Ford V-6 powered Mustang II. My opinions about doing things certain ways are colored by bitter experiences like John's accident.
Above is the other end of the same high tension wire. There's a tab welded on the intake manifold supporting the wire with the -6 Adel. Again, the heat shrink underneath. When restrained like this, all of the motion of the engine moving is resolved between the two Adel clamps, and none of the motion is trying to pull the wire off the top of the cap or out of the box. If I want to look under the distributor cap, I merely unplug this wire, unscrew the cap, and fold it out of the way without undoing any of the plug wires from the cap.
Top view of Dave's engine, above. Note the little tab holding the top of the dipstick still. On the back of the starter motor is an aluminum angle formed into what we call the tail bracket. Our Starter Kits include these. If you're building your own version of our front starter system from plans, this bracket will make it rock steady. Note how well the front starter tucks underneath the nosebowl.
Side view of the Dynamometer. We've recently done some work on it, like the permanent mounting of the oil filter housing, some new instrumentation, and a safety switch. An engine built with our standard configuration of welded on head pipes and Rear Oil System can be mounted on the dynamometer by Kevin and myself in less than 10 minutes. At the upcoming Corvair College, we intend to run as many engines as possible. Dynamometer priority will be given to standard configuration engines. Please note that some rear starter configuration engines cannot be mounted on the dyno. We're going to try to have a second test stand available for odd configuration engines, but our primary focus will be test running engines built according to the Conversion Manual. Shown on the dyno here is Dick Proos' 601 engine. It is the 16th engine we've built this year. Kevin and I primed it, wheeled it outside, and turned the key for literally one second before it started and ran perfectly smoothly for an hour. This is the type of experience that you can expect from your own engine if you build it carefully.
Above is an overhead shot of The Turbo Skycoupe. It's undergoing a few airframe modifications, like a new cowling and hydraulic brakes. It has lived at our place the past six months, and will remain here through Corvair College, where builders can inspect it closely and see flight demos of it.
This T-shaped item on our Front Alternator Bracket is the tachometer sending unit. This is a magnetic sender that counts the teeth on the flywheel. It's available from www.contrexinc.com. It's .375" in diameter and 1.38" long. Above, it's mounted in two intersecting pieces of 4130 tubing I've welded into a T. There's a 3/8" hole drilled in the alternator bracket. The leg of the T has a bolt threaded into it from behind. The 3/8 sender is a light press fit down the T of the tube. It's held .010" away from the Ring Gear. This provides rock steady tachometer information to the Stewart Warner tach we use. It's ideal because it's 100% divorced from the ignition system. Perhaps my greatest argument against using most electronic instrumentation is that the tach portion of a system like the Grand Rapids unit is directly wired into your ignition. There is no guarantee that if the unit fails, it will not fry your ignition and shut off your engine. No one I spoke to at Grand Rapids expressed any interest in this possibility. I would rather fly with no tach at all than with one that could cause the engine to shut off.
This is the rear baffle on our 601 engine. The sparkplug wires pass through a sheet of 1/4" thick polyethylene. This material is commonly called UHMW. The holes for 8mm sparkplug wires should be drilled at 5/16". If you have a reason to remove the sparkplug wire harness, the four screws at the corners of the UHMW block can be removed, and the wire set, including the boots, can be slid through the hole. The block has to be put in while the sparkplug wires are being made. As you look at the block from this side, the plug wires across the top, left to right, are 1, 4, 5; the bottom is 6, 3, 2. This yields the cleanest layout. The wire set is my recommended Accel 5041, available from SR. If you want the wires in black, put a K suffix on the number, or R for red, B for blue. We sell prefabricated wire sets with the block installed for $100. If you're going to build your own wire set, you absolutely must use the MSD crimping pliers to put on the terminal ends. We've had several builders bring wire sets to us that I could disassemble by pulling with less than 10 pounds of force. Poor crimping on ignition wires is very dangerous.
Above is our 601's version of the high tension lead security. The 601's MSD 8210 and coils are inside the firewall. This firewall pass through is an MSD unit, available from SR. Notice how all the motion of the engine will be resolved on the wire in between the two clamps. This wire is covered in red fiberglass braided cloth made by Mallory, also from SR. The 1.25" scat hose is used to cool the gascolator. Gus and I faced 100 degree temperatures the whole way to Oshkosh this summer, and installed it as a precaution against vapor lock. In the foreground is the sending unit for a JPI fuel flow meter. The 601's engine compartment still has more instrumentation and plumbing than I would consider necessary in a builder's airplane.
Here is the oil filter housing on the 601. It differs from Dave's plane in a single detail: The oil pressure line is T-d into a connection for a Nason SM2C20F switch. This is a requirement on a 601XL or any other airplane which runs the fuel pumps the full time the plane is flying. Typically, this would be a KR-2 without a header tank. Any highwing airplane or plane with fuselage mounted tank should be able to use gravity feed, and be exempt from this switch. In normal operation, the fuel pump will only run when this switch senses oil pressure. Thus, if you had an accident with the plane, the engine would stop, the oil pressure would go away, and the fuel pump would automatically shut off, even if you were not awake to turn it off. The backup fuel pump does not run through this switch. I am adamant that airplanes that do not need fuel pumps, such as Pietenpols, should not have them. The Skycoupe engine can produce 130+ horsepower, and yet it is fed by gravity out of its fuselage tank. If you have a 601XL, we have this system perfected and proven in 250+ flight hours. Please use it just as shown. The red line is Mallory fiberglass jacketing with the wiring inside. This is zip-tied to the Mount, and is highly resistant to abrasion and heat. It is much cleaner than a bunch of individual wires.
This is a motor mount bolt on the 601. Again, it is an AN35-6. It is using a spring clip in place of a cotter pin. The wires zip-tied to the mount are the alternator output and tach signal wires. These are jacketed in HILINE heat shrink tubing.
Top view of the 601 engine. The main line for the starter runs down between cylinders 2 and 4. It is in a piece of steel tubing, and protected by heat shrink. It has two layers of heavy duty heat shrink sleeving. Although it's a clean installation, most builders would be better served by the starter line passing through a phenolic block on the back baffle. Almost all of our starter wires are done by the latter methodology.
The cooler above is a folded fin. We've done back to back flight testing with the folded fin vs. the 12-plate. A slight edge goes to the folded fin. The welded on low profile aluminum intake pipes also can be seen in this photo. The rubber hose connecting these pipes to the intake manifold is 1.5" fuel filler hose from NAPA. Never use radiator hose on an intake manifold; it will disintegrate. Kevin and I saw this on an O-235 engine built by somebody who knew better. His defense? Radiator hose was cheap and available. With a nod, we wrote him off. I don't abide cheap, dangerous people. The proper stainless steel hose clamps are also available from NAPA, Balkamp part no. 705-1062.
This is the top view of the 601's intake manifold and MA3-SPA carb. The intake is one of our stainless one-piece models. Note how the throttle cable approaches from a vertical position. The small braided line is a -4, which runs to the manifold pressure gauge. The large braided lines in the foreground are the oil lines. The harmonic balancer is a Dale brand rebuilt model we use on every engine we build. It's available from C. The dual fuel pumps are also visible in the photo. Again, these would not be required on a gravity feed airplane. This intake manifold does not have a primer because the accelerator pump built into the MA3-SPA functions as an excellent primer.
Above is a $29 set of engine instruments straight from Discount Auto Parts. If you think I'm joking, I'm not. These mechanical pressure and temperature units are cheap, accurate and reliable. Every other week or so, I hear from someone who paid $1,000 for a Grand Rapids electronic instrument package. My very first question is: What kind of carburetor do you have? Often, the answer is a $200 non-overhauled aircraft carb or some unit salvaged off a motorcycle. This is insanity. If you have $1,200 to spend for instrumentation and carb, spend the lion's share of it on the carb because it's going to make the engine actually run. Besides the fact that the electronic units have unreliable sending units and questionable performance, no piece of instrumentation is going to make your engine run better. I can watch a $15 mechanical oil pressure gauge and see a flicker in the needle caused by rough operation of the bypass valve. You can never see this on a digital gauge. Additionally, if your generator goes offline, and the voltage coming out of your battery drops, mechanical pressure and temp gauges will still read accurately while electronic ones will shut down as voltage drops. I have spent the past decade teaching people how to build reliable powerplants on a budget. You don't have to read between the lines to tell that I believe the video game stuff is a big waste of money.
Two tools from the Precision Engine Building Department. On the right is a surface plate that Kevin developed to allow precision machining of the cylinder head gasket area. He spent a lot of time studying the procedure for milling heads, and decided he wanted to torque this plate to the head to allow greater accuracy when milling it. It paid off with precision repeatable results. On the left is the crank bore tool. This is a solid piece of 4140 that was turned down near the case bore diameter from a 3" piece of round stock. Dave did this by making a zillion passes on the lathe. We then had it heat treated to a very high level of hardness. Next off to the crank grinder for an absolute precision grind. A Corvair case placed in an assembly jig without bearings can have this tool laid into it and when the case is torqued, this tool forces it into alignment. The case can then be held in place by ARP case studs. The case is then disassembled, cleaned and assembled with the actual crank. We do this on almost all of the engines we build. This tool cost nearly $1,000 to develop. Sharp eyes note that the end of it is larger in diameter. This end of the tool is to align a fifth bearing placed right behind the prop hub. The September 2005 Hangar Update discussed this project. We'll have more details at Corvair College.
Here's the beginning of Dave The Bear's exhaust system. The starting point was a set of our Exhaust Stubs and Clamps. The stubs are 1.25" pipe. Here, the front elbow is 1.25", the first step up is 1.375", and the elbow is 1.5". Only the center clamp is in place. If you want to make your own exhaust system like this one, let me suggest tack welding it on the airplane, and then clamping it to a spare cylinder head for the actual welding. Early model cylinder heads have the same exhaust spacing, are worthless, and can be used here. We have a very heavy duty jig that performs the same function. After welding, the head pipes can be tapped lightly to align with the exhaust system. Dave's setup will be sent to Landshark Coatings in Valdosta, Ga., for ceramic coating. Landshark is a family run business with an excellent combination of price and service. Check in your local area, because there are many ceramic coaters in the country who do good work. There are high end shops like the Moore Brothers and Jet Hot, but they are expensive and perhaps overkill. Our original 601 exhaust was done by the Moore Bros. It was a fantastic job that really held up, but cost almost $300. Remember, do not ceramic coat the area of your exhaust system you want to use as a heat muff because ceramic really resists any heat transfer.
Above are two deep nitrided cranks from our second batch through the process. A very important point about nitriding: The items in my hand are the slinger ring, fuel pump eccentric, spacer and distributor drive gear. These absolutely need to be removed before the crank is nitrided. The nitriding makes the spacer more brittle than glass. If it is nitrided, it could easily be shattered by reinstalling the balancer, and you wouldn't know it till the parts went through your engine. These pieces are easily removed and replaced. We are now having our third batch of nitrided cranks processed, and they are due back at the end of this week.
This breather is the one we use on all installations. It costs $40 from AC and works as well as units that cost 10 times as much. The size of the hose connections is 5/8" and 3/8". We modify the left hand side valve cover by welding in tubes to match these dimensions for vent and oil return, respectively. The fittings in the foreground are Earl's 120 degree swivel seal -6s. The Marvel Mystery oil can is Dave's stylish brake fluid reservoir.
An overview of the 601 baffling. Although it looks large in this photo, it all tucks inside one of our sleek Nosebowls. This style of baffling and the round inlet style cowling we have pioneered for the Corvair has now been proven on our own 601, as well as a customer KR (now flying with our new KR cowling), and on Dan Weseman's Cleanex. All three of these installations run cool. It is hard to argue with success like this. By making cowlings and nosebowls available, these are easy systems to duplicate. I understand the attraction of duct style baffling, but it's nowhere near as practical or flight proven. Almost all builders would be best served by making a system just like the one above.
Above is how we install rocker arms today. At the beginning of my Conversion Manual, I state that I reserve the right to get smarter. While there is nothing wrong with the previous ways in which we secured the rocker arm nuts, here is how we build every engine these days: The NAS nuts are available from AC, the grade 8 nuts are from your local store, the grooved balls are from C. We have a tumbler set up with ceramic media to clean and polish GM rocker arms. None of the replacement rocker arms, especially not the ones made by Pioneer, have the correct geometry to use stock length pushrods. Thus, we use reconditioned stock rockers. The rocker studs we also tumble and inspect to ensure they're not bent and have no nicks or grooves worn in them.
Above is a special tool I made to check the torque on the lower row of studs with the rocker arms assembled and in place. This is not commonly used in our shop. In general, it is not necessary to retorque the heads on a Corvair. In a conversation with a builder recently, he discussed relaxing the torque on the upper row of studs only. This is a very bad idea. It is a tremendous invitation to blow a head gasket or warp a head. If you loosen a single one of the head studs, you absolutely need to go back, untorque the whole head, and go through the whole torque pattern in stages again. The history of Corvair autos is filled with stories of blown head gaskets following people replacing the O-rings in the pushrod tubes without retorquing the whole head. The above tool lets us retorque a head without losing the rocker arm adjustment. This is something you'll likely never need, but the main point is do not untorque any of the head studs individually.