Simpl question for the right person------maybe
 

I run a regular model A distributor with modern points and condenser and 12 volts. I decided I would try a high performance coil out of curiosity. I know little of automotive electronics. When I connected the new coil my car stumbled and would hardly run. I put the old coil back on and it ran fine. I tried another time making absolutely sure everything was connected properly and had the same result. So now I am back to the older coil with my car running fine. I don't get it . Switching the coil should be simple! Could the condenser have anything to do with it? Any suggestions?

Re: Simpl question for the right person------maybe
 

Re: Simpl question for the right person------maybe
 

Re: Simpl question for the right person------maybe
 

The new coil may need an external resistor and the other may have one built in. Gary

Re: Simpl question for the right person------maybe
 

I would say that 9 out of 10 new 12v coils will be needing an external ballast resistor for use with points.

This should look similar to this one;

Re: Simpl question for the right person------maybe
 

Re: Simpl question for the right person------maybe
 

the opposite could also be the case. Maybe he has a resistor with his old coil and the new coil doesn't require one. Then you wouldn't have enough voltage to run the new coil.

Re: Simpl question for the right person------maybe
 

I put the old coil back on and it ran fine.

so why are you messing with it then?

Re: Simpl question for the right person------maybe
 

A new 'high performance' coil is not going improve anything as long as everything is as it should be.

The fellas covered it, points should only have 6-8 volts feeding them requiring a resistor somewhere, either outside of the coil or internal. Ohm reading will tell or the coil should have it printed on it maybe.

Also the new coil could oil filled. They do not like to be tipped upside down. You could try pointing the connections skyward and see if that helps.

Re: Simpl question for the right person------maybe
 

Old engineer's saying:
"If it's not broken, mess with it until it is!" :D

Re: Simpl question for the right person------maybe
 

my old coil was a standard coil for a 1968 mustang. It used an external resistor. My new coil was a petronix 1.5 ohm which does not require an external resistor. Everything was connected correctly--honest. The reason for wanting to switch was to see if I could get my plugs to burn a little cleaner. My problem may be because I require a coil with 3.0 ohm rating-not really sure

Re: Simpl question for the right person------maybe
 

are you sure your battery is fully charged older stuff can sometimes run on lower voltage where something high performance may take more juice to operate properly.

Re: Simpl question for the right person------maybe
 

Put a resistor on your coil. 1.5 ohms is not enough resistance for the primary side of your ignition system. The primary current will go up and You will burn the points.

As Al in NY stated, you may now have way too much voltage to the plugs that something may be arcing to ground.

Even modified Model A Fords do not require extremely high voltage to the plugs.

My opinion,

Chris W.

Re: Simpl question for the right person------maybe
 

I'll bet you're right. When I bought the coil I was told no resistor was needed so that was how I connected it. I just looked over the info that came with the coil and it says a resistor is needed for a 4cyl application. I'll find out tomorrow.

Re: Simpl question for the right person------maybe
 

Being a 4 cylinder won't matter for the coil and resistor. Using 12 volts on a 1 1/2 ohm coil instead of 6 volts is what does matter, and makes the resistor necessary.

Re: Simpl question for the right person------maybe
 

today I put the new 1.5 ohm petronix on the A using a resistor as suggested ( even though instructions that came with it said no resistor needed). It ran great and idles smoother than with the old coil

Re: Simpl question for the right person------maybe
 

Re: Simpl question for the right person------maybe
 

You are right . The petronix webpage indicates that but the info included with the 1.5 ohm coil doesn't. The 1.5 does work great with a resistor however. Actually I already have a 3.0 on order so I won't need a resistor---thanks

Re: Simpl question for the right person------maybe
 

burning the plugs cleaner probably has more to do with the mixture being rich

Re: Simpl question for the right person------maybe
 

Maybe but I run as lean as I can without it sputtering