AQ125B ignition coil

[jmwill73]

I'm narrowing down my ignition problems and have learned that my ignition coil isn't sending spark to the distributor. By taking the coil wire off of the distributor and holding it close to the engine block, I couldn't get any spark to arch as the key was turned. Does anyone know of any aftermarket coils I can pick up at the local auto parts store? Does it have to be marine, or will one that fits the spot do the trick?

Also, when I took the coil out, I noticed a red "button" hidden behind it marked with a "40". Can anyone tell me what that might be? It kind of looks like a reset button, but it doesn't really do anything when pushed.

 

[Mullin]

Re: AQ125B ignition coil

It is probably the points not making contact. But to answer your question, yes you can use a aftermarket off the shelf coil. This is the old oil filled type of ignition coil and there are basically just two types, internally or externally regulated.

You can check to see if you have a ballast resistor or resistor wire going to the coil, or none at all. You can also check the coils resistance with an ohm meter as well as the new one to verify what you are getting matches the old.

My 125a was an internally resisted version. I just asked for any old coil from say a 1970 chevy 350 anything and matched it up from there. Really the only differences aside from the resistance would be the primary +/- connections; most of the old stuff is the same but there are some coils with fancy clips and junk.

Most of the high performance stuff from Accel or Msd etc. are not internally resisted and would require an external resistor.

 

[Maclin]

Re: AQ125B ignition coil

Regarding "narrowing down my ignition problems", I would like to expand on Mullins' comments about the points.....when was the last time a good set of points was installed and dwell checked/adjusted? The points "tell" the coil when to build up charge and when to discharge. It would not be much fun to install a new coil and have the same problem(s).

 

[Maclin]

Re: AQ125B ignition coil

I am not an expert on your rengine setup, but if I had to come up with an idea about the red button it is probably a 40amp circuit breaker. A circuit breakler willl not do much when pushed unless it had been tripped prior.

 

[Alan Lloys]

Re: AQ125B ignition coil

Maclin is correct.

I have the same exact engine and the 40A is the main breaker.
Kind of interesting that it is put on a 50A alternator but I guess it is better than the other way around

 

[jmwill73]

Re: AQ125B ignition coil

UPDATE:

As it turns out, my distributor had been fitted with an aftermarket electronic ignition conversion kit. I inadvertently connected a 12V wire to the negative side of the coil when trying to find the right wire for the tach, which I believe fried the module. At least that's the best I can figure, since the set of directions I found online said in bold letters, DO NOT CONNECT 12V TO NEGATIVE SIDE OF COIL.

Regardless, I'm going to replace it. However, I'm considering buying the original parts, which consist of the switch kit and capacitor. (Already bought the cap, rotor, and plug wires.) Any advice would be appreciated. I'm hoping to get it back to close to original, but if the conversion kit is better, I might go that route.

I'm still having trouble understanding why, upon testing the coil, I'm getting a very weak spark. I bought a new one, and both the old and new are only sending a weak spark through the coil wire. I expected to get a strong white spark through them. Perhaps the internal resistor is weakening it. I don't know.

Thanks for the info so far.

 

[Mullin]

Re: AQ125B ignition coil

Check the voltage at the coil. It should be 12+ unless there is an inline resistor. If there is a resistor and then the coil is resisted too, that could be a problem.

I'd personally stay with the electronic ignition. The hot-spark kit is only $50 and doesn't need to be tuned every year like points.

 

[jmwill73]

Re: AQ125B ignition coil

Thank you for the reply. I do have 12+ volts at the coil. The sun was shining bright, so perhaps I just wasn't seeing the bang that I thought I should see. Maybe with the new electronic ignition conversion kit I'll get more bang. Now, I just need to find where I can buy the Hot-Spark kit for $50. Any suggestions? The only conversion kit I could find was the one on this site, which is $126.