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On Board Air!
By Steve Delanty
On board air!
Anyone
who owns a shop air compressor knows what a conveniance
it
is. Filling tires, running air tools, cleaning and drying parts,
etc,
a
compressor is almost a must for any serious gearhead !
But
whadda Ya do when You want compressed air out on the road?
Well,
You just plug Your air hose into one of the air fitting that's dangling
under
Your front or rear bumper of course!
When
I decided I wanted an on-board air compressor for my '71 F100
I
built a cheap and simple system from an old air conditioning compressor.
Here's
how I did mine:
First
thing was to aquire an old air conditioning compressor.
One
of the most desirable types of compressors to use for on board air
is
the old York compressors, which were used on zillions of old Ford
(and
other) vehicles in the 60's, 70's and 80's. These compressors are an
upright
2 cylinder design with a built in oil sump. The oil sump is inportant,
since
some compressors have no sump but rather circulate lubricant oil
along
with the refrigerant to keep the pump lubricated. The only way to
lubricate
a "sumpless" compressor in an on-board air setup is to use a
pre-oiler
on the compressor inlet which is not a very desirable way to go.
Most
of the York type compressors have an oil sump to contain the
lubricant
oil, so they need no external oiler to keep them healthy.
The
York pumps have a model # tag bolted to the cylinder head, and
may
have a number something like this: F2
10R 16909
The
center group: "10R"
is the important group to look for.
You
may find 3 models of this compressor which all look similar:
"6R",
"8R", and "10R".
The "10R" is
the most desirable since the larger
numbers
have longer strokes and so move more air.
If
You find an "L"
instead of an "R"
after the number, don't worry it means
that
the air outlet is on the left side of the pump instead of the right side...
Once
I had the pump in hand, the next thing was to find a mounting
bracket
and crankshaft pulley for the pump. That was easy, since the
York
A/C pump was used as stock equipment on almost all the
older
A/C equipped Ford cars and trucks.
I
found an A/C equipped, FE390 powered truck at the wreckers and
grabbed
the mounting bracket and 3-groove crank pulley from it.
Everything
bolted right up to my motor in a matter of minutes...
Here's
a photo of it installed:
When
used as an A/C pump, the compressors are lubricated by a mineral oil
based
lubricant. There is no conveniant way to check / fill / change the oil
onmost of the York pumps without removing the sump pan.
If
Your pump is full of oil when You get it, and You only intend to use the
compressor
occasionally, the mineral oil lube will probably be fine for years.
I
intend to use my pump a lot, so I modified mine a little...
I
removed the sump plate and head and thoroughly drained and cleaned all
the
mineral oil based lube out of mine. Then I drilled and tapped a hole for
an
1/8" pipe plug as close to the bottom of the compressor sump as
possible.
That's my drain plug... Then I drilled and tapped a hole a
little
higher
up the crankcase, about where the oil level should be when full.
That's
my oil level check hole. I also drilled and tapped a hole near the
top
of
the crankcase and screwed a pipe elbow into it so the elbow points up.
Then
I screwed a 1/8"" to 1/4" adapter onto the elbow and screwed a short
length
of 1/4" pipe into it with a pipe cap on the top. The cap has a 1/8" hole
drilled
in it. The 1/4' upright pipe has a wad of fine mesh stainless steel
screen
stuffed into it to catch oil. This little assembly forms an external
crankcase
vent, which reduces the amount of oil carried thru the pump and
expelled
into the compressed air, since in stock form the pump vents the
crankcase
to the pump air inlet...
When
i was done the pump looked like this:
After
the pump was drained and mofified, I refilled it with a straight 20W
non-detergent
oil. I feel better knowing I can check and add oil to my pump
once
in a while...
Once
the pump was set up and mounted, I needed an inlet air filter.
i
made a filter assembly from a plastic electrical box, a chunk of air filter
foam
rubber, and some screen. It's not the most elegant setup,
but
it's what I had laying around in the garage...
The
outlet air from the pump is plumbed into a manifold that splits off to
a
pressure switch, a pressure relief valve, an air pressure gauge, and two
air
lines, one that goes to a quick disconnect under the front bumper and
one
that goes to the rear of the truck. The one to the rear splits under the
bed,
and one hose goes to a portable air tank in the bed, and one goes to
a
quick disconnect under the rear bumper.
You
MUST use a pressure relief valve!! The York
compressors
can easily produce pressures well in excess of 200 PSI, and
can
burst Your air tank! The pressure relief valve should be rated for a
pressure
equal to or lower than the rating of Your air tank.
Mine
is rated at 150PSI.
An
air tank that explodes can send You or someone else to the hospital
or
the morgue, so please be carefull, O.K.?
Once
the air plumbing was done, the last bit was to hook up the wiring.
Power
comes from the igntition switch, so the pump clutch can only be
energized
when the key is on. Power then goes to 10 amp fuse, an
"air
on/off" switch on the dash, then to the pressure switch, then to the
compressor
clutch.
When
the engine is running and the power switch is on, the compressor will
fill
the tank to about 115PSI then shut off. It comes back on when pressure
drops
below about 105PSI.
I
managed to scavange used/surplus parts for almost all of my system and
ended
up with a $$ investment of under $70. I use it to run air tools,
adjust
tire
pressures, fill air matresses and inner tubes at the lake, and much more!
Now
that I've got on board air, I dunno how I ever did without it!
(-:
Happy
motoring!