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Discussion Starter #1
OK I have a coil that has power going in but no spark coming from the H/T lead going to the distrubtor cap. Has new Bosch coil installed (internal resitor). Power in is 10.90 volts. Power drop at crank is 8.5 volts. Anyone want to take a crack at this?
 

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Trained (ex)Professional, , 1953-2018 RIP,
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What year and model Alfa?

Only 10.9 volts at the coil indicates that either there's a ballast resistor somewhere, excessive circuit resistance or a flat battery.

By 'Power drop at crank is 8.5 volts' do you mean the voltage at the coil during cranking is only 8.5V?
 

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Discussion Starter #4
No Spark at coil?

The car is a 77 Alfetta GTV with single point distrbutor. It has a new Bosch coil with internal resitor. Power off the wires at the coil is 11.9 Volts. Power with wires connected to coil with switch on is 10.9 Volts. Power during cranking is 8.5 Volts. It has a new condenser, points and cap. Plug wires are Taylor brand and in good condition. Guys, I am in a bad spot. I wanted to take her to the French Italian show at Woodley Park (Van Nuys Ca) today, but she has turned into a bad date. I just need to get some spark out of the coil H/T wire.:mad:
 

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Trained (ex)Professional, , 1953-2018 RIP,
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16,232 Posts
Your Alfetta was originally fitted with a ballast resistor so I need to ask exactly how is the new coil hooked up? There should be a single green/black stripe wire to the coil positive terminal. The green wire on coil positive, used with the old coil, will not be used and should be taped up and secured out of the way.

If you take a voltage reading from the coil negative terminal while cranking, is the voltage steady? Or does the voltage vary between zero and coil input voltage?
 
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