Blairm
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| posted on 2/1/05 at 05:26 PM |
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X-flow alternator and spark issue
Hi,
Please excuse double posting as I originally accidently put this in the wrong area.
After many months of procrastination and excuses about being to busy at work I have finally sat down and wired my car.
Most circuits work as I expect except the alternator and ignition. Reasonably important ones I suspect?
The alternator is a Lucus unit with 2 large common positive terminals and the indicator terminal. I have run 2 wires to the battery connected to the
battery side of and isolation switch on the dash, but are un sure as to the wiring for the charge indicator on the dash.
Do we feed 12 volts from the iginition switch in the the light and then connect the ground side of the bulb to the wire from the alternator?
The motor is not a runner yet (plumbing to be finished as well as the iginition problem next) so I am not able to confirm it is charging, but figure
and working charge indicator would be a good start.
Also I have connected the distributor wire to the negative on the coil and are feeding 12volts from the iginition switch to the positive on the coil.
When the motor is cranked I do not have spark at the points. The last owner had the distributor overhauled by an autoelectrican so I assume it is all
good. Any ideas as to where I should start looking for the fault?
Thanks and Happy New Year
Blair
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VinceGledhill
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| posted on 4/1/05 at 01:10 PM |
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The bulb works like this.... excuse the naff drawing but this is esentially the circuit.
+ from ignition - - - - - Bulb - - - - Alternator - - - - - through alternator field to earth.
What happens is that when the engine runs the field of the alternator gets excited. Basically once charging it puts a positive feed on the alternator
side of the bulb. So... you have positive at one end.... positive at the other. So the light goes out.
If you ever suffer from a dim bulb it is because of a blown diode in the output section of the alternator and therfore shows a 3v difference.
So if you follow the cirtuit above you'll be fine.
Ref the destributor. This is wired correctly. Make sure you've got a new condenser fitted (not much money) because this is a vital part. If
you think of electrons as gremlins running down the wires then this is a cul-de-sac for the gremlins. They all run in, then just at the right time
(points open) they all run out again with some vigour.
Why not try turning the engine over with the central wire (HT) close to the engine. This will determine if it is on the primary side (points
condenser etc) if you get a good spark there but not from a plug then replace the cap and rotor arm (worth doing anyway)
P.S. remember that HT through your arm hurts. Make sure it sparks to the engine and not you.!!! you have been warned.
Regards
Vince Gledhill
Time Served Auto Electrician
Lucas Leeds 1979-1983
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