what will a bad coil do to the motor??

[treihesse]

How will the motor run? I think mine is shot. Also how much voltage should there be to the coil after the resistor.

 

[DirtDonk]

What are the symptoms? You'd likely be experiencing less power, less ability to rev up to the higher rpm ranges, rougher running, especially at idle. Maybe it even acts up more when it gets hot. As opposed to running better when it's cold.
Things like that.
With your electronic igntion though, you could get any or all of those same symptoms from a worn distributor, bad or mis-adjusted magnetic pickup or reluctor, cracked cap, bad plug wires or a bad connection somewhere. Next it could be a bad module. And yes, they usually just "fail" all at once, but that's not a gurantee. Just a most-common scenario.
Votage at the coil can read 12 volts but should be between 6 and 9 when running. I think someone will correct me here, but I think it depends on how you're using your meter as to what reading you'll get. Viperwolf is up on this type of stuff so might answer that.

Paul

 

[Landho]

Motor will run crappy or not at all... misses, fuel smell from exhaust because fuel isn't burned, backfires. Similar symptoms if you had a bad distributor (bad rotor) or bad plug wires.

Which coil do you have today? Some claim to have 50,000+volts

I am no mechanic or no expert - but understand that coils are harnessing a lot of heat and stress, so they do go bad for sure.

 

[treihesse]

just wont run right rough as hell wont run when timed right

 

[Viperwolf1]

It would be missing and backfiring. It may actually run ok at idle. That is when the air-fuel mixture is the least dense and the easiest to push a spark through. When you get on the throttle more air and fuel is going into the cylinders each cycle and it takes more voltage to push the spark through. If the coil is bad it can't generate the high voltage to jump the plug gap. No amount of timing advance will help it do this. I don't think the coil is your problem.
6-9 volts when running is about right.

 

[thegreatjustino]

When mine went bad, it would idle fine and drive alright, but would constantly stall. When I tried to re-start it would crank slowly like the battery was low on juice. Eventually, I could not re-start at all until the coil cooled off.

 

[wildbill]

Saying it wont run when timed I would look and see if it jumped time. Mite be time for a new timming chain and gear set. Good luck.;D ;D ;D Bill %) ;D