Loosing spark

[Automotive Stud]

1947 with the original motor. It is converted to 12v negative ground. I have a Mallory ignition coil with a ballast resistor mounted on the firewall in line to it. I have a problem where when I'm driving it looses spark. It just shuts off and won't restart. I check with a test light and I have power going into the ballast resistor but nothing/not much coming out. I replaced the ballast resistor with a new one and I replaced the Mallory coil with a NOS Mallory coil and I still had the same problem. The second time I bypassed the resistor by hooking the two wires together and replaced the Mallory coil with an old Ford yellow top coil. At the time I thought it was internally resisted but now I don't think it was, but it got me home. By the time I get home I hooked up the Mallory coil and ballast and the car started right up again. Anything else I should be looking at?

[scooder]

I see you replaced coil and resistor. Always best if you can swap on known good parts. New parts are irritatingly commonly no bloody good from the factory.
What about the condenser? The quality is very questionable on these across many different brands.
Known good are the key words here, will help immensely tracking down the problem.
Martin.

[Automotive Stud]

You aren't the first person to mention to condenser. The first time it happened I swapped distributors and it still didn't start. Would the condenser cause me to get funny test light readings at the ballast resistor?

I agree I've had my share of bad new parts out of the box. But it does seem funny that I get the same symptoms, makes me think I'm missing something. The coil I had on there originally was a swap meet mallory voltmaster style coil. The new one I put on was an original NOS voltmaster style that was the same part number.

[Automotive Stud]

For what it's worth, I am using a #29150 Mallory "electronic ignition coil" with a Mallory #700 ballast resistor. I'm wondering if its not the right coil for running with points. Though before I put this NOS one on, I had another 29150 with another one of the same type resistors on the car for about 5 years with no problem. Now they have both been replaced and I still have the same problem, a problem that goes away when I bypass them...

[AnthonyG]

Check for weak grounds. When you think you have the problem nailed and even with new parts the same condition avails it self start looking at your grounds. Do all the basics, fresh clean electrical paths can solve a lot.

[Automotive Stud]

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That's a good idea. I'm pretty sure I have a heavy ground strap on the back of the block. I'll double check it.

[19Fordy]

I have a Mallory electronic ignition in my 8BA and directions say to use only Mallory coil # 2916. For Mallory dual point ignition it says to use Mallory coil# 29217 on an 8BA. Not sure if the same info applies to the early flathead.

[Automotive Stud]

I'll have to see if I can get ahold of anyone at Mallory. I'd really like to use the vintage coil, but if it's going to cause me problems I might have to go to a more modern style. I hope that solves my problem at least. I don't know what else it could be really. Just seems odd that the nos coil has the same problem the old one did that ran fine on there for years.

[Automotive Stud]

Originally Posted by AnthonyG

Check for weak grounds. When you think you have the problem nailed and even with new parts the same condition avails it self start looking at your grounds. Do all the basics, fresh clean electrical paths can solve a lot.

I looked tonight. I still have my 1" braided ground strap from the bellhousing to the firewall in good shape. I put a multimeter from the distributor housing to the negative battery terminal and I got .2 ohms. Going from the cylinder head to the negative terminal on the coil gave me 1.0 ohms. All the connections look clean too, so grounds don't seem to be a problem.

Originally Posted by 19Fordy

I have a Mallory electronic ignition in my 8BA and directions say to use only Mallory coil # 2916. For Mallory dual point ignition it says to use Mallory coil# 29217 on an 8BA. Not sure if the same info applies to the early flathead.

Hum, I do have a spare 29217 Mallory on the shelf from my '67 Mustang. I suppose I could do away with the ballast resistor and put this on there to see if it solves the problem, but I was hoping to keep using the old Voltmaster for the looks. After all, there are a lot of old parts on this car that could be replaced with something more modern that would probably function better, but that's not really my objective with this car. Then again, I want to be able to reliably drive it regularly. I've been able to do that for years until this problem came up.