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by John
Rollins
Recently
I installed a modern radio-cassette player in my BJ8. This presented a problem. Try
and find a positive ground radio. I couldn't. Initially I overcame the problem
with a voltage inverter. This worked fine, but I was left with other unacceptable
problems. With the radio on, the voltage inverter produced a high pitch whine that
was quite annoying. With the radio off, the inverter will drain your battery. With
the battery off, your nice new radio will lose its memory and the clock will stop.
The solution,
I surmised, must lie in converting to negative ground. Quite simple once all the
facts are known. However, I could not find all the facts from anyone person. Once
I put all the pieces together and made the conversion, I thought perhaps other
newcomers to the world of Austin-Healeys might
appreciate some help.
The worldwide
standard (except Britain,
prior to 1968) is a negative grounded electrical system. Some Freightliner heavy-duty
trucks (even today) use a positive ground. Freightliner says positive ground saves
on instrumentation. Others debate on the flow of electrons. For the unknowing, jumpstarting
a positive-grounded vehicle could be costly and dangerous. For the purist-well,
only you and a few wires need know.
Step 1.
Disconnect the battery, do not reconnect until everything has been double checked! You should install a negative ground fuel pump. The newer pumps can be ordered with
a negative ground. They hook up exactly the same as the original pumps and the newer
ones are much more reliable. Incidentally, for no apparent reason, I had a devil
of a time re-installing the new fuel pump. I had little or no room between the ground
terminal on the pump and the fuel outlet connection. I thought I would be clever
and rotate the pump coil housing. Wrong. There is a cast lug on this housing and
this lug must be in the bottom position in order for the fuel pump to work. Why?
I do not know. This little bit of trivia cost me two repair manuals and about three
hours of harsh words directed across the Atlantic. As with
all things mechanical, be patient and persistent. The mind can overcome
the wrench.
Step 2.
Reverse your battery. Just tum it 180 degrees or reverse the cables. Turning your
battery is the best procedure. Put another way, you want the cable running to the
starter solenoid connected to the positive post on the battery.
Step 3.
You must reverse the wires on your ignition coil. The original coils were marked
CB (contact breaker) and SW (switch). The newer coils will be marked with a plus
sign(+) and a minus sign (-). The SW is negative (minus sign) and the CB is positive
(plus sign). There are three wires connected to the coil. You want the single wire
(should be white with a black tracer) going from the SW or - terminal on the coil
to the distributor. The remaining two wires should be coming
out of your main wiring harness. There should be another white wire with a black
tracer and a solid white wire. Connect the white wire with black tracer to the SW
(-) side of the coil and the solid white wire connected to the CB (+) side of the
coil. To say again, connect both white with black tracer wires to the SW (-) side
ofthe coil and the single solid white wire to the CB (+) side of the coil. If these
connections are not done properly, you will fry the distributor tension lead wire
(the little plastic goodie that mounts on the side of the distributor).
Step 4.
If you have a mechanical tachometer, you may skip step 4. If you have an electrical
tachometer you must read on. The electrical tachometer must also be converted. First,
remove the tachometer. Carefully remove the
chrome ring and the glass cover. Remove the two screws (on the back) and gently
remove the internals. The spade terminal (white or green wire) carries the power.
Next to this is the ground connection. Unsolder the wires and possibly the resistor
and reverse them and re-solder. Reassembly is the reverse of the above procedure.
(Sorry, I had to say that just once.)
 Step 5.
Now for the famous wire loop. When you removed the tachometer you should have noticed
the wire loop, a green wire and two light sockets. The lights and the green wire
stay the same. The wires on the wire loop must be cut and reversed. Simply follow
the drawing.
Step 6.
Turn the key to the on position. The red ignition light should come
on. If by chance you did not connect the coil wires correctly, smoke will be wafting
from the distributor cap. If this happens, recheck your connections. Assuming there
is no smoke, start the car. The red ignition light should go out at about 1000 rpm.
If you
do not get a red ignition light, most likely the polarity of the generator did not
reverse itself. In most cases, the generator will reverse polarity. If it does not,
here is how to help it along. There are two wires connected to the generator, a
heavy gauge wire (should be brown with a yellow tracer) and a light gauge wire (should
be brown with a green tracer). Remove the light gauge, or "F" terminal,
wire. Now take a length of wire with bare copper showing at both ends. Attach one
end to a hot lead [i.e. positive post of the battery or, closer yet, the" A"
terminal on the control box which is located on the right hand side of the firewall.
Take the other end of the wire and quickly touch the "F" terminal on the
generator. Just flick it a couple of times. Look for sparks. That alone should reverse
the polarity of your generator.
One final
word of caution and encouragement.
On occasion,
this procedure will push your voltage regulator over the edge and cause it to fail.
This did not happen to me, but it could happen. If this occurs, assume that your
regulator was weak to begin with and it would have had to be replaced soon in any
case. Also, as with all things electrical, be certain that all connections are properly
made and tight. A bad connection anywhere will make it appear that all your efforts
have been for naught. The above procedure may sound lengthy and difficult. It is
not, and can be done in a matter of three or four hours. I believe the effort is
well worth the benefits.
Acknowledgement:
John Twist, Sport and GT Market, December 1983
Austin-Healey
Magazine. March-April 1989
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