The Best Au-To Yet

By Staff
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Bob utilizes a “wipe”-type ignition on his engine to conserve energy in the total-loss system.
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Owner/builder Bob Best bought these two Au-To air compressors at an auction to use as a foundation for building the third air compressor engine in his collection.
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The little inverted engine runs like a champ and looks good doing it. Bob TIG welded strips of 0.050-inch brass onto the cast iron flywheels, covering up years of damage and corrosion.
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If this inverted engine looks familiar, well,
it should. Two very similar engines appeared in Gas Engine Magazine
in both the February 2004 and January 2005 issues, both owned and
built by engine enthusiast Bob Best of Kansas City, Mo.

I caught up with Bob at the 11th Annual Power of the Past
Antique Engine and Tractor Show in Ottawa, Kan., this September. As
I was walking the show grounds that morning, just taking everything
in, I noticed an engine I knew I had seen before. Upon closer
inspection I confirmed that yes, this was the little burnt-orange
air compressor engine featured in the January 2005 issue of GEM. It
had those unmistakable lion heads and feet on the base, and I knew
there could only be one set.

As I approached Bob’s engines I saw another larger, brighter
engine sitting next to the little burnt-orange one. Just like his
other engines, this one is made from an old Au-To air compressor.
Or rather, two of them.

Bob bought two decrepit Au-To compressors at a farm auction just
outside of Lawrence, Kan., this past spring. He bought the pair
because each of them came equipped with a belt pulley on one side,
and Bob wanted matching “pulleyless” flywheels. So naturally, that
required him to buy both compressors.

The crank, rod, cylinder and piston are all original, yet the
engine still produces good compression. Bob machined the inside of
the working side flywheel to secure the necessary governing
flyweights. The cast iron flywheels were so badly pitted that Bob
cleverly TIG welded strips of 0.050-inch-thick brass onto their
faces. It turned out so well, even looking at it in person you’ll
never know what he’s done until he points it out to you.

Ignition timing is controlled via a “wipe”-type ignition. The
long, black shaft that runs vertically up the engine pushes the
exhaust valve down and won’t make contact again until the valve is
ready to close. Bob says it’s essentially a spark saver, which
conserves a lot of energy in his total-loss ignition system. The
timing gears are store-bought 2-to-1 ratio gears. Rather than use a
multitude of pieces, Bob machined a cam onto one of the timing
gears to make a one-piece unit. The bracket just under the working
side main cap is made from a steel plate designed for securing
railroad ties to the ground.

The cylindrical piece under the head (where the spark plug is
located) was a piece of 1/2-inch wall steel tubing, which Bob
thinks may be a cylinder from some kind of aircraft (Bob was a crew
chief for 30 years in the fuel division of what was TWA prior to
his retirement). According to Bob, this piece took a considerable
amount of machining to make it work. He also cut a small access
hole in the side of it so he can keep an eye on the exhaust valve
and make any necessary adjustments.

Fuel is introduced through a mixer built by Bob. It is similar
in design to the mixer seen on his blue Au-To engine in the
February 2004 GEM. It is made of simple brass fittings, with a
brass venturi inside, soldered in place.

The muffler was cast by one of Bob’s fellow Mo-Kan Antique Power
Assn. (Kansas City, Mo.) club members, Leonard Arbor. Bob claims
Leonard does a lot of casting for the club members and his work is
always top-notch. The heavy, sphere-shaped gas tank was originally
used as a watering bottle (for watering flowers, plants) from
India, bought for $10 at a swap meet. Bob machines his own grease
cups because he claims he can make them faster than they can be
shipped to him if he bought them.

Bob prepped the engine’s surface, then custom-mixed his own
shade of Rust-Oleum paint and sprayed it on the engine. He then
took his trusty polisher to all the brass, as well as the steel
crank, shining everything up to a high luster. After that, he went
around and pinstriped the engine in a nicely contrasting gold.
Finally, he built a “scrap wood” base that’s been planed, sanded,
routed, stained and top coated with polyurethane. The wheels on the
base are your everyday, run-of-the-mill cast iron wheels found at
most any hardware store or Harbor-Freight-type outfit.

Anyone who has taken on a sizeable project such as this will
know just how many trips it takes to various scrap yards and
hardware stores to get everything needed to complete such an
undertaking. Bob says he, too, had to make countless trips to get
all the right materials. But noticing how resourceful he was, I
asked, “You’re quite the recycler, aren’t you Bob?” to which he
replied, “I just prefer to use what I’ve got before I buy something
I don’t really need.”

As for the inverted compressor engines, Bob claims this is the
last one he will build, as this is the third one. All we can do now
is hope he changes his mind.

Contact engine enthusiast Bob Best at: 3521 N.W. 60th Terrace,
Kansas City, MO 64151;

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