;e TCM O-200
Its history and some helpful buying hints
BY TIM KERN, EAA ;;;;;;
TELEDYNE CONTINENTAL MOTORS ;TCM; started building small flat four engines just
before World War II, with continuous horsepower ratings of 40, 50, 65, 75, 85, 90, and
finally 100. When light-sport aircraft breathed new life into the market for a small-ish
Continental, TCM got inspired to upgrade the O-200. Technology had progressed, and
TCM saw an opportunity to enhance longevity and e;ciency while reducing weight, since
a fully accessorized O-200-A or -B could weigh as much as 225 pounds.
When Continental “re-introduced” the O-200-A at Oshkosh 2005 (and Mattituck
introduced its TMX O-200, an essentially new engine built under the customer’s old dataplate), both the light sport and experimental crowds were heartened this would guarantee
parts and support for years. Rumor held that TCM hadn’t been making or supporting the
O-200, though, in fact, the O-200 had never been out of production. In its highest production year (1966) some 3,200 were produced, while more recently fewer than 20 left the
factory in Mobile, Alabama, annually.
Today’s newest model O-200-D is called the O-200 Light Weight, and it is Cessna’s
engine of choice for its new Model 162 SkyCatcher. ;e O-200-D’s weight reduction plan
has resulted in a savings of at least 25 pounds. Obvious changes include lightweight acces-
sories—starter, alternator, mags—and smaller components, like a smaller, lighter,
Interim improvements are shown here, including the trimmed cylinder fins and some smaller accessories, but still utilizing the large sump.
A company photo in 2007 showed a front-mounted alternator drive,
no-fin cylinders, and no visible sump. This version was never released.
lower-capacity oil sump. Additional metal was
removed by trimming the cylinders’ cooling fins.
One test model eliminated the cylinder fins altogether. ;ey weren’t necessary for cooling, but
TCM learned that fins helped maintain the shape
of the cylinders and beefing up the no-fin design
to provide su;cient sti;ness added more weight
than the small fins!
Additional weight-reduction came from drill-
ing the crankshaft and cam, trimming the
propeller hub, and even stamping the valve covers
from thinner steel. In the earliest models of the
O-200, the “structural” valve covers retained the
floating rocker shafts. New shafts are retained by
a screw anchored in the center
support. In any event, ECi fur-
nishes Teflon buttons to use on
the oldest-design rocker shafts.
;e basics have not changed.
;e O-200D retains the vintage
configuration for 100 continuous
horses: a 4.06-inch bore and 3.88-
inch stroke. It’s now running on
100LL and featuring the popular
Stellite exhaust valve seats; that
hard steel alloy (with cobalt, chromium, molybdenum, and
tungsten) generally behaves well
at high heat and with unleaded
fuel. But don’t run this
Continental on unleaded mogas.
;e rest of the metallurgy won’t
give you long TBOs on unleaded
or ethanol mixes.
It’s di;cult to make things
stronger while making them
lighter, but the new -D incorporates substantial engineering and
metallurgical improvements: the
crankcase’s main bearing bosses