provision for a propeller. Its forged General
Motors four-main crank is plenty strong for
automotive use, but when a propeller
becomes part of the setup, you’ll need to
have a good inspection, nitriding, and some
polishing. The latest big development is a
fifth bearing, installed to support the prop
end of the crank. Two suppliers dominate
that market, and both approaches seem
to work.
WHY A CORVAIR?
The engines, properly built, are reliable and
of adequate power; they’re plentiful; stock
and hop-up parts are readily available; six-cylinder engines run smoothly and sound
cool; and best of all for some of us, they’re
inexpensive. A solid, safe, well-built Corvair
can fit your firewall for well under $5,000.
So can a crummy one—so it’s important to
learn a few things first.
SEEK HELP
Anyone who approaches Corvair power
will encounter William Wynne, and that’s a
good thing. He offers parts, books, the
traveling Corvair College, and solid advice.
He has examined hundreds of conversions—
some good, some bad—and when he
recommends something, it’s because it has a
proven record.
Wynne has become a devotee of the fifth-
bearing setup. Though Corvairs by the
hundreds have flown without the added sup-
port, some of these also have had their
cranks fail. With a proven fifth-bearing
setup, none has. Without getting into deep
detail, there are two popular systems afloat:
Dan Weseman provides a new casting that
bolts to the end of the engine case. Roy
Szarafinski uses a billet-carved, multi-dowel,
precision-honed, specially designed housing
that he mates and line-bores to your case.
Both support the prop end, and each has a
distinctive external oil line to the new bear-
ing that tells everybody, “I’ve done it right.”
Roy says, “A lot of what we do has
developed over the past years, analyzing
others’ mistakes. …Basically, we’re taking a
¾-inch wide bearing and making a 3-inch
wide bearing out of it…. The outside edges
take all the wear.” Roy’s system is not a set of
parts that a homebuilder can add to an
existing engine; the cases and crank need to
go to Roy’s Garage, which is actually a
PHOTOGRAPHY BY ROY SZARAFINSKI
Roy’s Garage offers a sophisticated fifth-bearing setup.
Top: Comparison to stock (bottom).
Center: Line-boring to hold the bearing.
Bottom: Precision hollow dowling ensures proper alignment.
sophisticated machine shop. Dan’s setup is a
bolt-on system.
With either system, builders are coming
around to the idea that the fifth-bearing
modification is the best 3½- 4 pounds
they’ve ever added to an engine. William
Wynne says, “The crank just doesn’t pulse at
all with a [fifth] bearing. No flex, no fatigue,
no failure.”
LIGHTING THE FIRES
Most Corvairs are flown with the stock, sin-gle-plug heads, but virtually none fly with
stock ’60s automotive ignition systems.
William’s system uses a recurved distributor
with both points and electronic trigger that
send current to separate coils and then to
the single plug.
Roy has tried welding the heads to install
twin “motorcycle” plugs: “There is a negligible performance increase. One spark is
perfectly adequate.” He offers the twin-plug
service, but admits, “I basically did it just
because everybody was talking about it.”
Virtually all Corvairs fly with one plug per
cylinder, though most employ some degree
of “dual” ignition.
INTAKE AND EXHAUST
The majority of Corvairs are carbureted, and
intake plumbing and manifolding present
few problems, as little attention is paid to
“ultimate” performance in deference to
“useful” performance and simplicity.
Popular carbs include the MA3-SPA straight
off an O-200 or a Stromberg NAS3 ( 1.375-
inch venturi, jetted for a C- 90). The Ellison
EFS-3A, too, is popular, and some fuel-injec-tion systems are available.
On the exhaust side, some builders use
the old cast iron car system; others go with
FlyCorvair’s tube systems, designed for a
number of popular applications. Still others
have designed and built high-performance
6-2-1 systems. Advice: Go conventional;
be happy.
GETTING IT IN THERE
The Corvair shape rarely presents problems
in installations. Proven engine mount
designs, with tough urethane shock absorption, are available from FlyCorvair.
Fortunately, flying examples of proven
mounts abound; often one of these can be
copied or adopted for a special application.
The Corvair is smooth in flight; most shaking occurs during cold starts.
DOING IT ALL YOURSELF
William Wynne offers support and information, as well as parts (and complete engines).
No matter how much work you plan to do
yourself, you should start with his Corvair
Conversion Manual. (William wisely writes,
“While…literature may tell you how to
