Last Corvair Engine of 2004
R. David Stephens of Belpre, Ohio, above right, stopped by on Dec. 29, 2004. He came and observed the test run of the
last engine we built in 2004. He liked it enough to buy the engine on the spot. It will be powering his Pietenpol in 2005.
The engine is a very nice conversion with a number of our custom options.
First House Call of 2005
New Year's Day 2005, Grace and I visited Phil Maxson and his family in Washington, N.J. We made a couple of comments
about how I have to be the only engine manufacturer in aviation who makes house calls. Phil built his engine in our
shop in 2004. Since we were visiting family in New Jersey for the holidays, we took the time to stop by Phil's and
check on his progress. In the photo above, Phil and I are replacing his stock oil filter housing with one of our new
Oil Top Covers. The stock guide was pulled out using the threaded rod trick and a propane
torch.
Here's a view of the development of Phil's 601XL tri gear. This is one of our standard mounts.
The carburetor is an Ellison EFS-3A. Phil's airframe is largely done, with the exception of the canopy. Flying this plane
to Oshkosh is well within the range of possibility.
A Very Sophisticated KR-2S
Above is a photo of KR/Corvair builder Stanislaw Jaglowski and Grace Ellen. A few days after visitng Phil, we drove
over to see Stanley's project. He built it in a single car garage in Hackensack, N.J. We'd never met Stanley in person,
just spoke to him on the phone and via e-mail. From his technical nature, I expected an outstanding project. These photos
don't do it justice. It is simply the most sophisticated and detailed KR I have ever seen. Stanley is a mechanic and an
engineer for a company that produces instrumentation and panels for airliners. He is a highly experienced commercial pilot
from Poland who emigrated to the United States many years ago. His aviation background shows in every detail of his plane.
A quick glance shows that his plane is about 85-90% done. The woodwork is very clean. The plane is equipped with a sliding
canopy with very smooth and positive operation. The empannage on the airplane is made of Kevlar skins. The engine is a
Corvair, absolutely no expense spared, based on 88mm cylinders. The panel for the plane, shock mounted to be removed with
four screws, is elegantly done to a very high standard. It includes a sophisticated GPS and auto pilot system.
The fuselage is widened to about 40". Whereas some airplanes with a lot of modifications often strike me as just a collection
of ideas, this one was notable because all of the work was extremely well integrated, making for one very impressive project.
We'll post more Bonus Photos from time to time to keep everybody in touch with developments in Corvair powered flight.
If you have a photo you'd like to have appear here, e-mail us and let us
know.
| Subj: MA3-SPA
|
| Date: 1/11/05
What is the part or serial # on the MA3-SPA carburetor that shows it came off an O-200 engine. There are a whole lot of
MA3s out there and I believe you stated that the O-200 carb works best on the Corvair.
Thanks, Ralph Young, Zenair 601, Emmet, ID
|
| Reply from WW:
|
| The part no. of an MA3-SPA from an O-200 is 10-4894. It is by far the most common MA3-SPA. Although there are
many other numbers, their production was small compared with the 4894. We've run other MA3-SPAs on the dynamometer and
they don't run as cleanly as the one from the O-200. The one on our own airplane has absolutely no rejetting or resetting
of any kind. We jsut took it off the O-200, cleaned it up and put it on the 601.
|
| Subj: Thrust loads
|
| Date: 1/11/05
Can't tell you how excited I am about the prospect of a smooth,
reliable, and affordable 100hp range aviation engine!!!! Have yet to
purchase any products, am curious about one subject area I didn't see
covered anywhere on your Web site:
How are the thrust loads absorbed by the engine? Are there
modifications to the main bearing assemblies? Or has it proved to
simply not be a problem with lightweight propellers? I'm somewhat
familiar with some VW conversions that go to great lengths to address
this issue. Any enlightenment would be greatly appreciated. Don't know
if this is covered in your Manual.
|
| Thanks. shatley@cafes.net
|
| Reply from WW:
|
| It is covered in great detail in the Conversion Manual. But in a nutshell, the Corvair
has an excellent double-sided thrust bearing from the factory. It has been flight proven over the past 45 years both in
tractor and pusher configuration. In all my years of experimentation, flight and reasearch into the Corvair, I have
not found a single case of an engine damaged by a bad thrust bearing. The bearing is actually on the opposite end of
the crankshaft from the propeller. Although it is important to use either carbon fiber or wood props on Corvairs, and
not metal ones, the thrust bearing would not be affected by the weight of the prop because of its opposite end of the
engine location. Your question highlights one of the Corvair's advantages: Its long history allows great perspective, and
means that no one using the engine today need be a test pilot or a guinea pig. Through our testing and information,
you can follow a proven set of parameters and have an excellent expectation of success.
|
| Subj: Head Studs, Paint
|
| Date: 1/11/05
I have a set of case halves that came to me with two missing studs. The
threads in the case *look* intact. Do I:
a) follow Clark's advice (pg 173) and try a stock, 0.003- or 0.006-over
stud? If yes, which LocTite would you use: none, #262, #242, #243?
b) assume the worse and repair with Clark's 1 inch-long Time-Serts
(#C8767L)? If yes, which LocTite would you use: none, #262, #242, #243?
c) other?
I have another set of case halves where some of the studs turned less than
an 1/8 of a turn when I removed the head nuts. Are the "turned" ones safe?
Others came out "clean" (no visible aluminum). Do I need to Time-Sert the
"clean" holes?
Looking through the description of your rebuilding of accessory cases I am
guessing that mine will come back in your "standard royal blue color." What
paint do you use (and from what vendor)? I want to match it on the case
halves and the cut-down bell housing.
So many questions :-)
|
| Craig Payne, Utah, Manual #6154
|
| Reply from WW:
|
| If you did not personally unscrew the studs and observe whether or not they took metal, then you need to do a
first class inspection. You could use a .003 over stud if you like, but we have had excellent test results with standard studs
and Loctite 620 with proper surface prep. There's a lot of information on this in the previous
Open E-mail. PLease note that when I say Loctite 620, I mean it. As good and useful as the other Loctite products are,
they do not hold a candle to nor do they have the proper qualities to act as a replacement for 620. My comments on using
stock size studs are only applicable if the proper Loctite is used, and used properly. You could use a time sert or a long
helicoil as long as you re-form the thread on the stock stud. If you do not wish to reform the thread on the stock stud,
you could always get an ARP head stud from Jeff Ballard at SC Performance. Our previous open e-mail details the thread patterns
on these studs and why it is crucial that the correct thread pattern be used with the stock hole or a threaded repair.
On your second set of cases, again you can read a detailed explanation on the previous Open E-mail about how to deal
with ones that unscrew cleanly. In my experience, a stud that turns 1/16 to 1/8 of a turn will not be a problem. Attempting
to unscrew such a stud will result in a stripped hole about 25% of the time. If the stud looks good and is not damaged
by corrosion or mechanical marks, I'd leave it alone. You could always double nut it and tighten it to 35 foot pounds of
torque to see if it tightens into the case again the 1/8 turn that it backed off.
The color is Ford Dark Blue Part No. DE1606 by Plasticoat.
|
| Subj: Tri Gear KR Mount
|
| Date: 1/8/05
I'm in Gettysburg, PA and building a KR-2. I do have your Manual, but it's in the hangar with the plane. I'm getting ready to
construct my engine mount and was told that since I'm installing the diel tri gear I must make some changes to it for
the nose gear. I couldn't find anything in the Manual covering this. Can you assist me?
|
| Thanks, Tim Boyer, KR2, Gettysburg, PA
|
| Reply from WW:
|
| Over the years, I've built 15 or 30 KR mounts to the design that Mark Langford and I worked out at
Corvair College #3. About 1/3 of these were for tricycle geared KRs. These tricycle gear aircraft were set up for the
Diehl nosegear. The Dehil nosegear has its own socket. The socket consists of a large diameter tube coming off a firewall
plate at a 45 degree angle. It's stabilized by two smaller tubes, which in the VW application, are bolted onto the back of
the engine mount. In our conversion, I cut off these two tubes and remove them from the main tube. They're replaced
by two 3/4" .049 wall tubes that run from the same location on the main tube back into the clusters, where the upper tubes
meet the back corners of the tray. There are good photos of this motor mount bolted onto a KR-2 without the engine
in place on Mark Jones' Corvair/KR Web site. I built Mark's motor mount a few years ago. It was one of the first tricycle
gear ones we did.
|
| Subj: Moroso Blue Max Wires
|
| Date: 1/9/05
Hi William, just a quicky. What is the part number on the Moroso Blue Max
spiral wires you reccommend ? I'm gonna splurge on the good ones. Thanks
|
| Terry Calderwood, 6419, Kitfox 7, Missoula, MT
|
| Reply from WW:
|
| The Moroso Part No. is 73225 if you want them in blue; it's 73217 if you want them in yellow; 73219 in red;
and 73231 in black. Summit Racing is an excellent source of Moroso products. You can find them on the Web. Notice that
these are eight-cylinder plug wire sets. The two extra wires provide you with enough material to make the leads for the
coil switcher and two coils.
|
| Subj: Stud Removal
|
| Date: 1/9/05
I've read a lot of stud removal ideas. The Snapon tool is good (probably the best). But here are some ideas that work
well on any stud. Double nut or triple nut if space permits; sometimes you have to use a thin washer to make the flats
align to get the socket in place. Use a little discretion and if that does not work then clean and degrease the stud and
nut and use red Loctite. Allow to set overnight or accelerate with a little heat (150-200F). This will almost always break
the stud or it will come out. Breaking the stud is not desirable so stop and apply a soft heat to the casting if accessible.
Follow up with your old candle trick or good grade of penetrating oil. Once the stud moves a small amount, then reverse
direction a few times while applying more oil. In a lot of cases, this will prevent stripping the thread as it comes out.
Use good grade 8 nuts (American made) and be patient. I have used this method for many years on both UNF and UNC threads
to very large sizes (1 1/2 diameter and larger). It also works well to install studs as the Loctite can be softened
by 300-400F heat, which will not damage the stud. William, I am sure you know all of this, but for the benefit of others,
this is my 2 cents.
Ray Simpkins, Piketon, OH, Manual #5389
|
| Reply from WW:
|
| A bunch of good tips that we're glad to share with Open E-mail readers. During all discussions on head studs,
I want to keep builders focused on the goal, which is to have a good set of reliable studs held in the case. Head
studs were some of the first sophisticated tests that we ran more than 10 years ago. Our work on this and flight
testing has been continuous, but the goal remains the same: Define easy and reliable techniques that builders can use
only if they need to.
Follow this progression: The best case scenario is to find a completely assembled core motor which has no major
corrosion on the top rows of head studs. In such a case, you can carefully disassemble the engine and, in all
likelihood, all the studs will be good, and you can be reasonably assured that none of the studs were damaged if you
did not use excessive torque to unscrew the nuts.
If any stud unscrews cleanly from the case during disassembly, inspect it carefully to ensure that it did not pull
out any aluminum. A faint tinge of silver on the stud is acceptable, but if it pulled a few slivers, the thread in the hole
should be considered damaged. In the first case, where it came out clean, the stud and the hole can be carefully
cleaned with carb cleaner or Brake Kleen, and then the stud can be reinserted after being coated with Loctite 620.
This Loctite will bond a stud in place which does not have significant drag torque on the way in. Just make sure that
you have a good coating of 620 on the threaded areas, and that you set the stud to the same height as the other studs in its
row. 620 is an amazing product that has gap filling capabilities and retains its strength several hundred degrees higher
than regular Loctite. If you're only familiar with other Loctite, you're out of the loop on this one. We order ours from
McMaster-Carr.
If you have a damaged hole where aluminum has been removed, you'll need some type of thread repair. Although this is
covered in detail in the Conversion Manual, in a nutshell, you will either have to put a
3/8-16 helicoil or time sert in the case. Clark's Corvairs sells extra long versions of each of these specifically for
the case. Drill the holes and tap them in a good drill press or mill. It's important that the hole go in as close as
possible to vertical. Resist the temptation to hand drill it.
Once the thread insert is in place, you'll need to put the stud in it. All stock and oversize studs have a very special
thread called a 3/8NC5. This thread is not compatible with helicoils or time serts. The appropriate solution with a stock
stud is to rethread the bottom with a 3/8-16 split die, as detailed in the Conversion Manual. When done properly, this will minutely
reshape the 3/8NC5 threads to 3/8-16. The alternative is to to call Jeff Balard at SC Performance and buy ARP head studs.
These are specifically manufactured with the 3/8-16 thread, and are directly compatible with helicoils and time serts.
Two notes on the ARP studs: You cannot use them in stock case holes because the 3/8-16 thread on them will not hold in
the stock hole, which has NC5 threads. Second, because the 3/8-16 thread on them is straight and untapered, it will have
no drag torque on installation. You will be able to screw them all the way in with your fingers. This is where the
Loctite 620 comes into play, and will seal and bond these in. You just coat the threaded area on installation, and insert
them to the correct depth.
If you're building a 2,900 or 3,100cc VW cylinder conversion, you cannot use helicoils on the head studs. There is not
sufficient edge distance for them. Time serts are an option, but this is best done by your 3,100cc machinist, be it Ray
Sedman at American Pie or the Wheeler brothers at Wheelerizing. Engines using Corvair cylinders can use any type
of threaded repair. Very rarely do we ever use oversize studs in an engine. My testing has shown that a Loctite 620 stock
stud threaded in finger tight in a stock hole exceeds the strength of a .003 or .006 over stud torqued in. If a stud
unscrews and pulls aluminum chips with it, you need a threaded repair, not an oversize stud.
We have built, tested and flown every combination I've written about here. I have more quality testing experience on
these thread repairs than anyone in the world of Corvairs. While bystanders may have differing opinions, invariably
I've found it's based on some personal prejudice, and no actual testing. I did our research to provide a safe and
reliable path for builders to follow, not to debate the subject with people who have no intention of ever building and
flying a Corvair engine. Studs are a minor task on the way to building the engine that will power the airplane of your dreams.
While some people will get bogged down or make a mountain of a molehill, the path to success is to just follow the
information here and in my Conversion Manual, and call or e-mail us if you have further questions.
|
| Subj: Roller Rockers
|
| Date: 1/9/05
I was wondering if you can shed a little light on the roller rockers in you 601 engine. I'm about to start my engine
re-build after 9 months of collecting and purchasing all the parts required. I purchased a set of roller rockers off
eBay, the same as yours. I'm interested if there is anything I should be careful of.
I have new alloy rocker covers to clear the extended rocker height, longer rocker studs, new Isky valve springs, new
valve guides and new stainless valves. The only thing that I have a concern over is the lengths for the push rods.
What was the difference you found? Were they required to be much longer? What did you do and where did you purchase
the extended push rod tubes?
Look forward to hearing your thoughts on this.
|
| Regards, Darren Barnfield, VP-2, Australia
|
| Reply from WW:
|
| As you noted in your e-mail, roller rockers are not a stand alone item. They require polylocks, longer
studs, deeper valve covers, and invariably, longer pushrods to correct the valve geometry. I'm pretty sure that our
601 is the only plane that's ever flown with roller rockers. We installed them not out of a sense of need, but
to flight test them in order to be able to provide useful commentary on them. My primary thought is that they might
reduce valve train wear or lower operating temperatures. Before flying them, I spoke at great length with Jeff
Ballard and Ray Sedman. The consensus was they'll certainly do no harm, and testing will reveal what difference they
make. As close as I can tell after 125 hours, I believe that they do not make an appreciable difference at our rpm.
When considered as a system that costs $500-$600, I think the money would be better spent elsewhere on most builders'
engines. For example, the same $600 could be used to upgrade from a Stromberg carburetor to a brand new Ellison.
Setting up the proper valve geometry is not a big deal for experienced engine builders, but it is a significant
challenge for most homebuilders. Engines built with stock rockers and Corvair cylinders usually have very good valve
geometry and almost always can run stock pushrods. Conversely, all the engines we've built with roller rockers or VW
cylinders have needed some type of custom pushrod length. Our pushrods in the 601 were 3/16" longer than stock, and were
provided by Ray Sedman at American Pi. He also provided pushrods that we used on other VW-cylindered engines that we built
in 2004. Each engine required a different custom set. Not a big deal for us, but you can understand why I would recommend
engines based on Corvair cylinders and stock rockers to 90% of our builders.
One more quick note: I am not a big fan of Isky valve springs. They may have been intended for a cam with far greater
lift and duration than an OT-10. Jeff Ballard has sets of appropriate springs that we use in all of our engines.
|
| Subj: Oil pressure sender range, Carbs
|
| Date: 1/8/05
In your new oil setup, what range do I need on the pressure sender at the
remote oil filter manifold? Or better yet what make and model of sender are
you using?
What *available* carburetor can I use on my Corvair engine in a Zodiac XL?
I'd use the Aerocarb but no one seems to be able to make it work in a
pressurized fuel system. Just searching the Web turns up some nice $1600
carbs, but that seems disproportionate for a $4000 engine. Does the rest of
the world flying Corvairs just happen to have a nice used carb sitting
around?
|
| Craig Payne, Utah, Manual #6154
|
| Reply from WW:
|
| Our 601 uses a Nason 15psi switch in the oil system. We are likely going to change this for a 10psi unit.
Stewart Warner also makes a virtually identical switch.
Aircraft like the 601XL and a KR-2 without a header tank are unique in that they require a carburetor which can
withstand fuel pressure. In my opinion, the two best carburetors for this are the Ellison EFS-3A, available brand new
for $850, and a Marvel Schebler MA3-SPA from an O-200. A good used MA3-SPA is worth about $300. We overhauled ours with
parts from Chief Aircraft, and we have about $450 in it. It performs flawlessly. There are any number of carburetor repair
stations in the U.S. that will overhaul an MA3-SPA or sell you one outright. This can even be done through Aircraft
Spruce, but you're likely to find better deals by reading the ads in Trade A Plane. Keep in mind that you must use
an MA3-SPA from an O-200. It is by far the most plentiful model. Perhaps 75,000 of them were made. Last year at Oshkosh,
I saw 40 or 50 of them for sale for less than $400. A number of our customers have called aircraft salvage yards and
acquired servicable ones for less than $500. $1,600 is a complete extreme on the price of a carburetor for a pressurized fuel
system. The Ellison is a first class option for half that. Steve Makish, Corvair/KR-2 pilot and
leading customer of ours, has flown more types of carbs on a Corvair engine than anyone I can think of. For the past 50 or
60 hours, he's flown an EFS-3A Ellison on his plane and he loves it.
For builders who are using gravity feed fuel systems, the selection is wide open. MA3s, Aerocarbs ($400 new), and
Stromberg NAS-3s ($200-$300 used) would be the most popular choices. Corvairs have successfully flown on Zeniths, Carters,
Harley carbs, etc. We have tested an enormous range of carbs, and the engine is not particularly sensitive to specific
carburetion as long as it is set correctly. The MA3 and the Strombergs have the advantage of being jetted right on the money
for almost all Corvair engines. Others will require some adjustments. Thus, people with gravity fed airplanes have a
great number of options for a few hundred dollars and down. I agree that $500-$800 for a pressure fuel system carb is not
cheap, but represents a small fraction of the done cost of your airplane. On the day it flew, we had about $22,000 in our
601XL. I consider the $450 we spent on the carb a fair price for the flawless performance and certified reliability
provided by the MA3-SPA.
|
| Subj: Oil system questions
|
| Date: 1/8/05
Hi William,
A few oil system questions:
1) I live up here in the frozen North of Montana. We run 5W30 in our cars in
the winter up here; the average winter temp is around 15 degrees. In the
summer we may hit 100 degrees once. Castrol Syntech also comes in a 10W40
weight. Would it be more appropriate for me?
2) I found that Fram makes an oil filter for the Corvair, part number PH4.
Can you use this in our conversion or is an external remote filter the way
to go?
3)What oil cooler with AN-6 fittings have people been generally using. I've
found some at auto part stores, JC Whitney, etc., but don't want to purchase
without guidance.
|
| Terry Calderwood, Kitfox 7, Missoula, MT
|
| Reply from WW:
|
| Your questions bring up the subject of integrated design. I use this term to refer to viewing the entire firewall
forward package as a whole system, rather than looking at it piece by piece. Using your Kitfox 7 as an example, and
discussing the oil system, I would recommend setting up your engine just like our 601 engine
(with the exception of using a gravity feed fuel system). This means I would use a front starter and alternator,
a 12-plate oil cooler in the stock location, and a remote oil filter setup using one of our Oil
Top Covers and a remote oil filter housing on the firewall. A Transdapt 1045 housing will allow you to use any number
of readily available filters that would have a self contained pressure relief. The housing is also the correct place
for pressure and temperature instrumentation. An engine set up this way will free you from having any type of
external cooler. Addtionally, our Nosebowl would be an excellent start on a cowling for your
Model 7.
My extensive testing of oil systems indicates that 5W-30 is a good option for cold weather operation in Corvairs. We're
currently using that same grade of Amsoil in the 601, even
in fairly hot weather. Thin oil like this does a much better job of lubricating engines in cold weather starts. Pumping
it is easier on the oil pump, and it has the advantage of never opening the bypass in the filter on a cold start, nor
having an appreciable pressure drop across the filter. As you know, I'm not a big fan of many of the homemade rear start
setups I've seen in the field because builders have ignored my warnings about creating excessive restrictions in their
systems. It is not difficult to imagine thick oil, cold weather and bad design teaming up to starve an idling engine of
oil flow to the rod bearings. Conversely, thin oil and good design will provide your engine with protection in the
coldest weather.
|
| Subj: Engine storage after conversion
|
| Date: 1/7/05
I love your new “Open E-Mail.” It’s just what I wanted to see. I’ve already updated my files. I can’t wait until the next
string.
I just purchased a 1965 convertible Spider. It’s in above average shape with new carpets, seat covers and a top in
boxes! The previous owner replaced the turbo engine with an RH engine, but included the complete original turbo engine &
parts with the car. I plan to rebuild the turbo engine and restore it back into the car (that will be my practice engine).
After that I plan to convert the RH using your Conversion Manual. I won’t be able to afford an
airframe for a few years, but at least I’ll have an engine. I want a 601XL.
My question to you is, is there anything special that I should do to the engine when I build it so it can be stored for
several years as I save for & build an airframe? I plan to store the finished engine on a basic auto-type engine stand,
wrapped and sealed in plastic. I will store it in my garage/shop in Southern California, so there won’t be a great deal of
temperature change or humidity to affect it. I read that I might not adjust the valves until ready to run it. I’ve had some
“car guys” say that I should use grease rather than your oil/STP for assembly. I’m looking for a more reliable opinion. I’ll
bet there will be other builders that build & store their engine before they build their airframe.
I enjoyed Corvair College 5 and my visit to your hangar in August 2004. Thanks Gus for the 601 ride!
Is there a schedule
for an up-issue of the Conversion Manual? If so, will there be a special price to upgrade my Manual #5876? Keep up the
great work! I wish your attitudes would infect more businesses that I patronize.
|
| Best to you all, Dave Thompson, California, Manual 5876, Wishing I was building a 601
P. S. You’ve got to update your pictures in the Zenith Aircraft Company Web site! Your 601XL is much too beautiful to
not be shown in its finished state. (Just my opinion.)
|
| Reply from WW:
|
| Congratulations on landing a nice Corvair land-based project. Quite a number of guys who never thought about a
Corvair car before caught the bug while searching out an airplane core. Dave Morris in Texas recently picked up a late
model turbo car and Pat Panzera in California has a turbo coupe in his driveway to work on when his plane is done.
There are many other examples, but the car certainly has a lot of appeal. Between Kevin, Gus and I, we own 8 or 9 land
based Corvairs.
I would not use grease in assembling an engine, even one that is to be stored. Not all grease is oil soluable, and it's
easy to imagine it clogging a filter or lifter, or restricting flow. STP and oil will cling tenaciously to machined surfaces.
As an option, you could spray the external surfaces of the crankshaft, the rods, etc., with a can of ACF-50, available from
Wicks or Spruce, before installing the Top Cover. It's the last word in preventing corrosion.
You could take the option of not setting the valves, so that the ports are sealed, although I'd obviously advise wrapping the
entire engine. We've stored engines for long periods of time, and if they're sealed up, they'll have no problems. Remember
also that you will prime the oil pump on the engine before you start it, so you'll be flowing plenty of oil through it
internally before it runs. If you wanted to be extreme, you could prime the oil pump intermittently over time, but I really
don't think it's necessary.
We've always offered low cost updates to Manual owners who originally purchased it from us. At our option, I have
frequently offered the same upgrade price to second hand owners. The main thing is we want to keep active builders
updated with all the information at their fingertips. We balance this against an occasional request from a second or
third owner of a 1996 Manual insisting he's owed a free update. We're friendly with everybody, and we expect people to
be reasonable with us. With any major revision, we will offer a major discount to any original Manual owner. Additionally,
we encourage all builders to subscribe to our newsletter, The Corvair Flyer. The Flyer is a
50/50 mixture of builders' success stories and technical information. A domestic Flyer subscription is $20 a year, but
we offer numerous specials to Flyer subscribers to allow them to recoup the modest cost of staying up to date.
We often hear that reading of other builders' successes in The Flyer is the motivator that gets people back in their
shops and progressing on their projects. So it serves several purposes.
Speaking of visiting the shop, for 2005 we've organized Thursday-Saturday as the best days to visit the hangar.
When a builder makes the trek to come all the way out to our place, we like to give them the full tour. Monday through
Wednesday traditionally are the busiest days in the shop, where the full crew is working a 10-12 hour day. Thursday
and Friday the pace is slower, and much more conducive to visits. Hopefully we'll see you again this year, but keep in mind
that calling first is a good idea as we have a lot of road events this year.
I'll ask Sebastien to update the Zenith Web site. You're right - it would look better.
|
| Subj: High Altitude Operations
|
| Date: 1/7/05
I live out in the Rockies and expect to often operate my engine at
10-12000' cruise altitudes. My original plan was to use a CV carb from
a Harley, but the specs for that carb state a 10000' maximum. Do you
have any experience operating your flight engines at those kind of
altitudes with the MA3-SPA carb? Any problems with mixture distribution
or specific recommendations? Also, what about running a Corvair engine
lean-of-peak, like I do in my O-320, for reduced stress on the engine
and higher fuel efficiency?
|
| Thanks, Andy Elliott, Mesa, AZ, Lycoming owner, Corvair wannabe!
|
| Reply from WW:
|
| Good to hear from you. Your e-mail is timely. It's two years ago this week we saw you at the San Antonio College.
Gus and Grace flew a 9500' cruise altitude to Oshkosh last summer. Gus reported perfect operation of the engine, and that
it responded to leaning in an expected and normal manner. Recently, Bill Clapp flew his KR-2S
to our place, and touched 14,000+ on the way. He has a 35mm Aerocarb (he's gravity feeding it from a header tank), and also
reported normal operation and response to leaning. While I have not made an extensive study of lean of peak operation on a
Corvair, preliminary indications and common sense suggest that what is applicable to horizontally opposed, certified air
cooled engines also applies to the Corvair. One of the many benefits of the Corvair's configuration is that I have
intentionally mimicked many of the features of certified engines, and therefore, operational experience is predictable and
bears far closer performance to certified models than other alternative engines. Translation: It's a good thing. Just
make sure you have good EGTs before really going after lean of peak operation.
|
| Subj: KR-1 Cowling
|
| Date: 1/6/05
Just a quick question, I've been looking for a KR-1 cowling for about a year,
check Trade A Plane, Barnstormers all the time. NO LUCK. The plans I have are not
very clear and hard to read. Any idea where I might get one that's already premolded or done.
You can e-mail or call me collect here most of the time (retired).
|
| Thank You for your time, Bill Sadler, Reno, NV, RENOSDALER@AOL.COM
|
| Reply from WW:
|
| We've put your note up on our Web site. We have a very big following in the KR community. Perhaps one of our
builders will be able to help you out directly.
|
| Subj: Fuel System
|
| Date: 1/6/05
Hey thanks for your reply.
I'm using an MA-3SPA and, on your encouragement, recently ripped out my
entire barbed fitting-based fuel plumbing and am replacing it with Earl's
fittings and steel braided hose.
The fuel flow is:
Main tank to Fram HPG-1 fuel filter to Facet pump to Header tank, with a
return path back to main tank and also a vent in the header.
Header tank to fuel shutoff valve, then via 3/8" aluminum tubing to
bulkhead connector through the firewall to gascolator to Facet backup pump
to Carb.
The flow from header to gascolator is entirely downhill. The gascolator
does not extend below the fuselage bottom. The problem I have is getting
from the gascolator to the carb without going uphill and then back
downhill, because I can't get the carb very much higher than the gascolator
due to the limited vertical space I have on the firewall.
I'm not so much worried about water as I am with fuel vapors migrating to
the high spot in the reversal and blocking the fuel flow.
By the way, it looks like my business trip to Florida is going to be in
early February now, and I have clearance from my boss to take some vacation
time to make sure I can throw my engine in the SUV, drive down there, and
spend some time with you guys getting my engine running after the business
part of the trip is done.
|
| Regards, Dave Morris, Dragonfly, Texas
|
| Reply from WW:
|
| Consider that we have run MA3s and Strombergs in both bowl forward and bowl rearward facing positions. Reversing the
carburetor may give you better options on throttle linkage or fuel feed routing. In either case, you may take some of the up
and down out of the line by routing it around the carburetor. Get a good look at all of the options for things like 180
degree full flow -6 ends. I don't think that you would have a problem with a vapor bubble in the line unless you let it get
way too hot. You have the option of firesleeving the line to insulate it. I have not done this on any of our installations,
and yet I have not experienced any type of vapor lock. Your fuel pump is an added plus on resisting any type of vapor
situation. An MA3 by design, like other float carbs with vented bowls, is particularly good at passing vapor. In short,
I doubt that you will have an issue with it. Before you fly the plane, you can block up the airplane at a high climb angle and
run the engine on the ground with the airplane tied down. With zero forward airspeed, you'll produce the highest
under-cowling temperatures, and it will be a fair test of the system's ability to flow on climb out.
Looking forward to your visit.
|
| Subj: Your Corvair/KR Cowling
|
| Date: 1/4/05
Rumor has it that you may be going to offer a cowling for the KR to use with the front starter??
Eric Pitts, Terre Haute, Indiana
|
| Reply from WW:
|
| Our latest issue of The Corvair Flyer newsletter has photos and a story on our
Corvair powered KR project. Did you get your copy yet?
|
| Subj: Fuel System
|
| Date: 1/3/05
I'm plumbing my fuel system on a Dragonfly firewall, which as you know is
tiny. I've changed my mind several times and ended up with the KISS
principal, using a gravity feed from a header tank and a backup Facet pump
in case gravity ain't enough.
Reading Tony Bingelis' Firewall Forward, he stresses that there should be
no reversals in the fuel flow between the gascolator and the carburetor. I
notice in your 601 fuel system, you've got the fuel flowing up from the
gascolator through two Facet pumps then back down to the carb. That sort
of configuration may be one of the few that would fit in my airplane, but I
wonder if the reversal will make the system vulnerable to vapor
accumulation or other problems associated with the high spot.
You've got a lot of flying time on different fuel systems, so what is your
experience with that configuration? Are you able to do the reversal
because your system isn't gravity-fed?
|
| Thanks!, Dave Morris, Dragonfly, Texas
|
| Reply from WW:
|
| Tony Bingelis stands out as the individual who did more to improve the quality of your plans built homebuilts
than any other person in the first 50 years of homebuilding. His magazine articles and four books are the standard for
detail design information on homebuilts. Tony passed away several years ago, but most of his information is timeless.
After 15 years of homebuilding, I could point to a few small items in his books that I'd disagree with in some
circumstances. This doesn't mean Tony was wrong, it means that he was writing for all homebuilders, and seeking to define
systems which would work in all homebuilts.
In some instances, the reversal of the fuel line is not an issue. Here's why:
Think of the gascolator as a sink trap. If it's anywhere in the system, it will trap any water passing through that point
until it is full of water. If I got more than a few CCs of water out of the gascolator, I'm going to drain a lot of fuel
out of it and run the engine extensively to ensure the system is clear. If there were water in the reversal, you'd find it.
One or two ounces of water going through a system will be strained out by a quality gascolator. If you have this
much water in your gascolator, you need to stop and investigate before you go flying. My personal preference in fuel systems
is no fuel lines in the cockpit under pressure, gascolator ahead of the firewall but above the bottom edge of it (this is
especially important on an aircraft like a Dragonfly, which could break the canard in a hard landing and lay on its
belly). Use a quality gascolator like the Andair. If you're going to use a fuel pump, it should come after the gascolator
so the gascolator is not subject to pressure.
The main issue with the line between the pump and the carburetor is that
it be a quality AN-style line, and have enough slack to allow for the movement of the engine. Preferably, you would firesleeve
this line. This will give it additional resistance to heating the fuel with engine compartment air. Keep in mind that fuel
has a boiling point around 170F under standard temperature and pressure. But it is significantly higher than this if it's
subjected to only a few psi. If you're using a float type carb, the only real good candidate for a pressure system is an
MA3-SPA. Keep in mind that once the fuel gets to the float chamber, it is no longer subjected to pressure, and its boiling
point would return to 170F. In our airplane, the engine compartment air runs about 100F hotter than ambient. However, the
MA3-SPA runs significantly cooler because the air flowing through it is outside ram air, and it has fuel vaporizing in it
continuously while it's running. Write us back and let us know what type of carburetor you're thinking of using so we
can discuss a few more details.
|
| Subj: Turbocharging
|
| Date: 1/3/05
Hi Mr. Wynne. I just ordered a Kitfox Series 7 and want to put a 164 cid
Corvair in it with aftermarket turbocharging. I have your Manual and the
Chassis manual. Can you advise/direct me to the info I need to build one.
Obviously I need names of parts, specific engine modifications outside the
ordinary for the non-turboed 164. I finally found an engine here in Montana.
Boy it wasn't easy out here! Thank you very much.
|
| Terry Calderwood, Kitfox 7, Missoula, MT
|
| Reply from WW:
|
| Not a lot of Corvairs found their way to Montana. I suspect it's easier to find 1960s pickup trucks in your state than
1960s cars. Glad you were able to track one down.
Kitfox Series 7 has a reputation as a well developed aircraft. A turbo 164 would likely provide outstanding performance
while remaining within the weight restrictions for the aircraft. Our turbo testing is still undergoing detail work.
But here is what we've established: Most important, the engine is clearly strong enough to take it. Second, it
has enough cooling capacity so that cooling's not an issue.
These are important points that stop other engines from effective turbocharging. The Corvair is the only production
engine I can think of that was built to be turbocharged without the use of electronic controls on the ignition or fuel
system, or a wastegate. These systems can be used to protect an average engine from hurting itself when turbocharged.
Typically, however, homebuilt aircraft do not utilize these systems and it's better to have an engine of robust construction
and plentiful cooling like the Corvair.
It should go without saying that a turbo engine
needs to be a first class rebuild. It should have connecting rods with ARP bolts from Clark's or SC Performance. The
cylinders should either be Clark's, or preferably, bored by Ray Sedman at American Pi. The rings have to be chrome. The exhaust valves
should be stainless steel and have bronze guides. I'd be very tempted to have the seats and guides done by Wheelerizing
in Brea, California. The only significant internal difference is the use of a TB-10 cam from Clark's in place of the
OT-10 cam. This cam is a version of the OT-10 specifically for turbocharged engines. We have dyno tested this camshaft in
two different naturally aspirated Corvairs to verify that it does not significantly reduce the engine's output when it is
not turbocharged.
We still have to develop and fly several external systems to come up with a combination that is easy to operate,
affordable and reliable. We'll be doing these tests in the coming months. The above recommendations are enough to go on
to build your engine for now, and we'll supply the systems information as we further develop it.
|
| Subj: 601 Cowling
|
| Date: 1/3/05
Are you planning on putting out prints for cowlings to match the Corvair engine installation? I need to know how much
overhang on the side skins do I need to leave?
|
| Roger Parnow, 601XL Taildragger, Crestline, OH
|
| Reply from WW:
|
| We're currently working on prints for the sheet metal parts of the 601 cowling. These sheet metal parts go
between the 601 fuselage and our Nosebowl. We made two prototype sets, and studied them
for ways to make them simpler, lighter and easier to fabricate. The drawings will reflect these improvements rather than
be simple copies of the prototype cowl on our plane. We're also going to offer cowling kits with all of the bending
work prefabricated. We have an extremely nice Whitney industrial finger break in house, and will be able to offer these
at an attractive price. The plans will be available free to anyone who's purchased a Nosebowl from us. We'll have pictures
of the cowling kits on the Web site in a few weeks. Our own 601 has 2" on the sides ahead of the firewall. I've seen
several builders' planes that are closer to 4" and would need to be trimmed later. Our intention is to leave the
cowling long on the aft side to allow for builder variation. It's a very simple matter to trim it.
|
| Subj: Oil Pan, Auto Gas
|
| Date: 1/3/05
I have read your Manual for hours and am surprised how
comfortable I am getting regarding building my engine.
I have a core and have taken it apart. After reading
about the mods you provide, I plan to use your system
for the 601XL. I have completed my rudder and was
pleased with the results.
My question is regarding the oil pan. I have what
appears to be a good steel pan, and have a question
regarding your pan. What are the advantages of having
additional oil if cooling is not a problem? It seems
that using the stock pan, and changing the oil more
often would be an advantage for using the stock pan.
Am I missing something?
For the future, I plan to use LL100, but if none is
availabe, does it hurt the engine to mix auto gas with
LL100, until you can get to a location where the avgas
is available?
Thanks in advance, and am looking forward to begin
ordering parts to complete my conversion. I still
need to build the airplane, but am hoping to finish by
July of this year.
|
| Regards, John Butterfield, Zenair 601XL, California
|
| Reply from WW:
|
| Traditionally, Corvair engines used a modified stock oil pan for Pietenpol flight conversions. This worked and logged
a lot of hours in Pietenpols. Many Corvair cores have damaged pans because it occasionally functioned as the skid plate
on the car, and careless mechanics used it as a jack point. Because of this, few stock pans are good candidates for the
traditional welded modification. (This mod is available in plans form from the Pietenpol family.) Today, the Corvair engines
we build produce more power, and we expect them to last longer. Our oil system modifications are based on these points.
Our Deep Sump Aluminum Oil Pans bolts right on and works with aircraft motor mounts. The
additional oil capacity has the effect of making the engine run cooler, and extending the intervals between oil changes.
The oil carried lower in the pan's sump allows the oil pickup to remain submerged in uncoordinated flight. For these reasons
we install our Pan on every engine we build.
You can mix 100ll and 93 octane auto fuel. The engine can be tuned to run on 93 continuously. I have more than 100,000
miles of driving Corvair engines on the road, and this was all done on unleaded auto fuel. I prefer avgas in flight
applications for a number of technical reasons outlined in great depth in the Conversion Manual,
but people who have better access to 93 octane fuel can utilize it with minor tuning changes to the engine.
|
| Subj: Little Wing Autogyro
|
| Date: 12/30/04
I have recently become interested in the Little Wing autogyro. I am wondering if you have any direct experience with this
machine. More generally, can a Corvair fly in an aircraft that can slow down like the gyro can?
Ron Herron, Little Wing's designer and builder, e-mailed me saying his opinion is that the Corvair is too heavy and
doesn't put out enough power for its weight, also that it overheats and needs a fan! (Maybe he hasn't had any recent
experience...) Thing is, the radial he has on his single-place gyro weighs around the same as the Corvair, but it sits
real close to the firewall. He has a two-place that is longer; builders have used the Rotax 914, the Hirth F30 and various
VWs.
What do you think?
Thanks, Jonathan Cartford, St. Paul, Minnesota, Manual 6417, no airplane, lots of dreams!
|
| Reply from WW:
|
| I have not followed the Little Wing extremely closely, but here's what gyro people who we're friends with share
with us:
Being a tractor gyro, the Little Wing has many flight favorable characteristics that few pusher gyros can match.
Tractor gyros are comparatively rare, and many of the things that people attribute to gyros across the board are not
true of tractors.
Prior to the installation of the radial, Ron told everyone that any engine weighing more than
200 pounds was too much for the design. I don't know if he made any changes to the airframe, but many people saw a
conflict between words and actions when he installed the R2800 radial. Your point that he may have zero experience with
Corvair engines and be operating on parroted information is a good one. In my experience, a lot of good airframe
designers are not engine guys and very few of them do any firsthand testing with engines. I strongly doubt that he has
any personal experience with Corvair engines. Consider the theory about needing a blower fan. Prior to our work with
Corvairs, this was a commonly held misconception. Anyone who reads our Web site can see that we've broken in and test run at very
high power settings dozens of Corvair engines on the dynomometer; notably, these engines were pumping out this power at
exactly zero airspeed with no blower fan. We've conducted break-in runs several hours long at continuous power settings
above 100hp. This is all done with the cooling baffle on top of the engine and the prop wash. This isn't to suggest that
Mr. Herron's a bad guy. Quite to the contrary, he has a number of admirers in sport aviation. I must agree with you that he's
just not up to date on our work with the Corvair.
I can assure you that a direct drive Corvair will produce more static thrust than a Rotax 912S. The 914, being turbocharged,
is slightly heavier than the 912S and even more expensive. The Rotec radial is a beautiful engine, but again, it's
astronomically priced. I haven't seen a Rotec on a scale, but I'm willing to bet a Corvair has a lighter installed
weight. You could build three or four very nice Corvair engines for the price of either one of these imported engines.
| Subj: Crank and Cylinders
| | Date: 1/1/05
I took my crankshaft to the shop and it has to be turned .030 under on the rods and .010 on the mains.
I've heard several comments saying that using .010/.010 cranks are good, but don't believe I've seen anything on what
the limits of a grind are. I see that Clark's has the bearings for them up to .030. Also the cylinders have a .005 taper.
Would you recommend boring the minimum (.020) piston or going to .030 for a little larger displacement? I was discussing
the crank grinding with the shop when I asked how far they recommended grinding the crank without going thru the nitriting
or Tufftrided. He said that crank isn't nitrided anyhow....because it has some rust on it, and nitrided cranks don't rust.
Is that correct? I suppose the nitriding was just on the journals only anyhow.
| | Blue Skies, Bob Unternaehrer
| | Reply from WW:
| | Almost every Corvair crankshaft we've dealt with would be perfect if ground .010/.010. I have a lot of flight
time on .010/.010 cranks. I'd be reluctant to fly a .030 under crankshaft. The availability of crankshafts for Corvairs
is so good that I would get another which could be ground only .010/.010. .030 under might work perfectly fine, but
that's a theory, not a flight proven fact. For building your own engine, I suggest you stay within previously tested limits.
The nitriding on Corvair cranks is only a few thousandths of an inch deep. Most crank grinders will tell you that
it is ground off by the time you do any type of work other than a light polish. The only Corvair cranks that were
nitrided by the factory went into 140hp and turbo engines. Your crank grinder is quite wrong; I have several rusty 140
cranks in the scrap bin awaiting conversion to a mailbox post. The cubic inch difference between a .020 over and a
.030 over engine is less than 1cid. That's roughly half a horsepower difference between the two engines, very negligible.
In the past, the main reason we bored engines to .060 over was for weight reduction. They are three to four pounds lighter
than engines with stock bores. .060 over adds 7cid to a stock engine, and makes a slight difference in power that we can
actually measure on the dynamometer. If you have a 1964 engine, we recommend .030 as an overbore, and a 1965-69 engine
can run .060 over. In the most recent Corvair Flyer newsletter, we have a bore vs. displacement
chart for the nine most popular bores on a Corvair, and a discussion on the combinations and recommendations.
| | Subj: Engine teardown
| | Date: 1/1/05
I'm in the process of tearing down, oiling, and bagging the parts of my core engine to preserve it for a future build.
After removing all of the headnuts and rocker studs, the heads are still VERY stuck. I hit the heads as hard as I dared
from every direction I could get at them using a block of wood and heavy ballpeen hammer, but they just won't come free
from the cylinders. Do you have any hints or tips for getting them free without breaking anything?
| | Thanks, Douglas Eatman, St. Augustine, FL, No airplane (yet!), Manual #6307
| | Reply from WW:
| | I'm glad you went straight from Corvair College #8 to purchasing a core. One of the reasons we recommend the best
condition core engines for purchase is the fact that some of the more corroded or stuck engines represent a real challenge
to disassemble. My gang in the shop have given up on only two engines in the past three years. With patience and
perseverance, virtually any engine can be disassembled with minimum harm to the engine, your tools and your fingers.
When a head is reluctant to come off, start by removing the pushrod tubes. Six pushrod tubes with dried out original O-rings
can put a surprising grip on a head. Look in the Clark's catalog or Richard Finch's book to see what a pushrod tube
removal tool looks like. Spray a lot of WD-40 down the sparkplug holes, and at the joint between the head and the
cylinders. I use a block of hard wood and a 2 pound hammer to get the head off. Watch the joint between the head and
the cylinders closely to ensure you're taking the head off square. If it's cocked at an angle, it's only going to bind up.
Tap around the perimeter of the head in order to keep the opening between the head and the cylinder uniform and square.
Keep in mind that many engines will want to stick the cylinders in the head, and have them slide out from the case.
This is OK, but you may need to unbolt the rod caps if the respective pistons will not slide out the bottoms of their
bores. Study it carefully and take your time. You may break a cylinder fin or inflict some other replacable damage. Don't
be discouraged: Some engines are just a bigger challenge than others. Write back and let us know when you get it all apart.
| |
