The Ford Barn

jchotrods · 04-04-2012, 11:36 AM

I put a brand new coil in my model A. Now the engine isn't starting and the coil is heating up. The only thing I cant think of is the internal resistor is bad or my points arent opening? Am I on the right track here?

BRENT in 10-uh-C · 04-04-2012, 11:47 AM

Lets start off with "why" did you change the coil?

Next, can you manually 'break' the points and cause the coil wire to shoot a spark?

jchotrods · 04-04-2012, 11:57 AM

I converted to a 12 volt system, hence the different coil. I am getting spark from the coil wire, when the engine turns over.

BRENT in 10-uh-C · 04-04-2012, 12:12 PM

If you are getting spark as the engine turns over, then the points are breaking correctly. Now you need to determine if the ignition is properly timed in relation to the piston. This procedure is covered in several places here on this forum so it really isn't necessary to go through all of that. Do a quick search here or on the internet.

Once you have determined the timing is within specifications, look elsewhere in the fuel area to make sure you are receiving the proper amount of fuel. Maybe the fuel mixture is too "rich", --or maybe not enough fuel. If it was running fine prior to the conversion, then I would hesistate to suggest you look for something mechanical that is defective. For the time being, check the timing and remove the spark plugs to check for fuel. Then report back as to what you have found and we'll go from there.

Purdy Swoft · 04-04-2012, 12:40 PM

Just to add to what has been said, Is the coil a 3.0 ohm rating??? A 3.0 ohm coil is what you need to run 12 volts on the model A without an external resistor. Other problems with overheating of the coil could be caused by a short in the armored cable or the popout switch. An oil filled coil mounted with the tower pointing down like the original is mounted can cause coil overheating and early coil failure. Are you running the so called modern points with the wireless lower plate ??? Slow cranking could be caused by having the wires reversed on the coil. If you changed to negative ground it will be necessary to reverse the wires on the coil and behind the ammeter. Just some thoughts, may not be the problem.

jchotrods · 04-04-2012, 02:57 PM

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Thanks for the imput, I will check on that and let you know what I find.

04-04-2012, 11:36 AM	#1
jchotrods Junior Member Join Date: Mar 2011 Location: Morgan Hill, California Posts: 19	coil issue I put a brand new coil in my model A. Now the engine isn't starting and the coil is heating up. The only thing I cant think of is the internal resistor is bad or my points arent opening? Am I on the right track here?

04-04-2012, 11:47 AM	#2
BRENT in 10-uh-C Senior Member Join Date: May 2010 Location: Eastern Tennessee Posts: 11,972	Re: coil issue Lets start off with "why" did you change the coil? Next, can you manually 'break' the points and cause the coil wire to shoot a spark? __________________ . BRENT in 10-uh-C . www.model-a-ford.com ...(...Finally Updated!! ) .

04-04-2012, 11:57 AM	#3
jchotrods Junior Member Join Date: Mar 2011 Location: Morgan Hill, California Posts: 19	Re: coil issue I converted to a 12 volt system, hence the different coil. I am getting spark from the coil wire, when the engine turns over.

04-04-2012, 12:12 PM	#4
BRENT in 10-uh-C Senior Member Join Date: May 2010 Location: Eastern Tennessee Posts: 11,972	Re: coil issue If you are getting spark as the engine turns over, then the points are breaking correctly. Now you need to determine if the ignition is properly timed in relation to the piston. This procedure is covered in several places here on this forum so it really isn't necessary to go through all of that. Do a quick search here or on the internet. Once you have determined the timing is within specifications, look elsewhere in the fuel area to make sure you are receiving the proper amount of fuel. Maybe the fuel mixture is too "rich", --or maybe not enough fuel. If it was running fine prior to the conversion, then I would hesistate to suggest you look for something mechanical that is defective. For the time being, check the timing and remove the spark plugs to check for fuel. Then report back as to what you have found and we'll go from there. __________________ . BRENT in 10-uh-C . www.model-a-ford.com ...(...Finally Updated!! ) .

04-04-2012, 12:40 PM	#5
Purdy Swoft Senior Member Join Date: May 2010 Location: Alabama Posts: 8,099	Re: coil issue Just to add to what has been said, Is the coil a 3.0 ohm rating??? A 3.0 ohm coil is what you need to run 12 volts on the model A without an external resistor. Other problems with overheating of the coil could be caused by a short in the armored cable or the popout switch. An oil filled coil mounted with the tower pointing down like the original is mounted can cause coil overheating and early coil failure. Are you running the so called modern points with the wireless lower plate ??? Slow cranking could be caused by having the wires reversed on the coil. If you changed to negative ground it will be necessary to reverse the wires on the coil and behind the ammeter. Just some thoughts, may not be the problem.

04-04-2012, 02:57 PM	#6
jchotrods Junior Member Join Date: Mar 2011 Location: Morgan Hill, California Posts: 19	Re: coil issue Sponsored Links (Register now to hide all advertisements) Thanks for the imput, I will check on that and let you know what I find.