Two or three freshly charged AA
Ni-Cds welded or soldered in series,
along with a transistorized system, are
More breaking in was required for
older engines because machinery
was less accurate. As with older
automobile engines, they were
typically set up with much tighter
clearances. The break-in procedure
produced that final close piston-to-cylinder fit needed for the best
performance. Many wouldn’t even
run out a tank of fuel without being
nursed through a number of runs at a
slow, rich setting.
The break-in procedure is roughly
the same as it is for a modern, non-ABC speed engine. The first few hand
starts are easier using a large propeller.
After finding the needle-valve and
spark settings, use a smaller-diameter
and/or lower-pitch propeller than
you’ll use for flying. A richer setting
allows a cooler run at a faster speed.
Consider advancing the spark as
being similar to leaning the needle.
Too lean or too much advance leads
to overheating and flameout.
1. Transistorized ignition systems
were covered in August 2007, June
2008, June 2010, and August 2010.
2. Reducing spark-ignition radio
frequency interference with 2. 4 GHz
radios, October 2007.
3. Freeing up frozen engines,
4. Basics of running spark engines
FF fliers Bud Romak and Bill Vanderbeek are njoying the moment. Photo submitted by Eut Tileston.
plus a wiring diagram, April 2008.
5. Fuel mixes, October 2011.
You’ll also find a wealth of engine-related information in many issues
of the Society of Antique Modelers’
(SAM) publication, SAM Speaks.
These are available on two CDs of 191
issues up through December 2006.
The US price is $32 postpaid. The cost
100 Model Aviation
AUGUST 2013 www.ModelAviation.com