Steve,
With the 67.5 and earlier roadsters: the ballast resistor is
never bypassed during start.
With the 68 and later roadsters: the ballast resistor is bypassed
when the ignition key is in the 'start' position.
Since you have a '68 roadster, you could be dealing with a
bad ignition switch.
SIMPLE TROUBLE SHOOTING
+12V ign switch
0---------o o----------/\/\/\/\------- "+" coil
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run |
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o---------o o--------------------
start
A SIMPLE troubleshooting trick:
Rig up a taillight bulb (I like the dual filament
park/stop bulbs). One wire soldered to the two contacts
on the bottom. Terminate the wire with a small alligator
clip.
Next wrap some wire around the base of the bulb. Drop
of solder helps keep it in place. Terminate it with a
larger alligator clip (for connecting to ground).
Use the 'test light' by clipping one end to the "+"
of the coil, other end to the chassis ground. If the
points are open, and ignition switch is on, you should
see the bulb glowing nicely. If the points are closed,
there is no voltage across the bulb, and it will be off.
Crank the engine... bulb should be visible, but with
a reduced brightness. Once the engine starts, you should
see the bulb glowing (remember it is really on only part
of the time).
Nice thing about the light bulb is you'll discover when
the electrical system is not functional.
BACK TO CHECKING THE REST OF THE SYSTEM:
On the 2000's, I have seen the wire connecting to the
distributor break inside the insulation. My own 2000
kept cutting out around 3,700 rpm due to this broken
wire. Thankfully I had made up a simple jumper wire
from the coil "-" side to the distributor spade connector.
Problem solved.
Inside the distributor are TWO wires. One to the points,
other is used for ground. If either wire is broken, you'll
have problems.
Also overlooked are the connections themselves. Since
you have replaced the coil, most likely you'll have
discovered any corrosion on the coil connections. Still
the distributor connection should be checked & cleaned.
I'll remove the distributor, and work on it on the
bench. Much easier, and less likely to drop a screw.
I'll pull the white plastic block up off the distributor,
loosen the screw, slip the inner wire off. With some
fine emery paper I'll clean every bit of the areas that
pass current. After 30 years you'll find dirt/rust/corrosion.
Just clean away with a little emery paper.
A little silicon grease (dielectric grease) will prevent
corrosion from reoccurring.
You'll also discover it is worthwhile to clean up the
ballast resistor connections, too.
Little patience, some Ale, and lots of time... you'll get
it tracked down!
Cheers,
Tom Walter '67 2000
Austin, TX '68 2000
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