I have a 1968 327 SB with a street performor cam, Mallory electronic ignition and Sniper EFI. A year ago the car would exhibit an ignition breakup above 2,000 rpm after about 30-45 minutes of driving (ran fine when engine was cold). I got a lot of different opinions on what the cause was but I was convinced it was the coil. So I bought an inexpensive AC Delco coil (made in China) on Amazon and that fixed my problem. Then about a month ago I had the same problem. Another Amazon coil fixed the problem. My question is about upgrading the coil. There are plenty on the market but all state they have an internal resistor. My '68 has an external resistor. Can I use one of these higher output coils and just eliminate the external resistor?

 

Is the Mallory deal like a pertronix? If so you may want to look at the instructions. If it is instead something like a MSD box you probably can eliminate the resistor.

 

The Mallory is a 1993 vintage tachdrive distributor. There is no separate control module. A new AC Delco coil and resistor were installed then and worked fine until one year ago.

 

Probably still requires the resistor. I would suggest a MSD high vibration coil. I had some coil issues years ago, and that coil fixed it.

 

I've had really good service from Accel Super Stock coils. 3 coils over 40 years, no problems of any kind

 

Spend 3$ on some dielectric grease. Works wonders and underrated

 

You might try a Standard UC12X coil which uses an external resistor. Make sure it is NOT a UC12 which is China sourced. UC12X is also known as a Blue Streak coil because it is blue! Last one I bought was made in Mexico where Standard Motor Products has a factory.
I have one in my carbed 84 C4 and one in my 65 Gto. Also use points distributors in both!

 

I too have the Holley Sniper on my Corvette and I have had issues with the coils. I have gone through Ignition Coils at an alarming rate before and after the Sniper Installation. I am on my 3rd in five years or so, they were all the MSD brand standard round coils. If you are using the Holley Sniper to control your ignition as well I would go through the software and make sure it is set up properly. I have been using an MSD ignition for decades and after a call to the MSD tech support they suggested that I buy the more expensive coils as the vibration is what they claim is killing the coils. The Holley Sniper system supplies 12 volt power to your coil and if it is not designed for 12 volts continuously you might have a reason for the failures.

I have my coil mounted in the same location as the factory setup and have not been using any ballast resistor in the circuit. I plan on going to the more expensive Blaster coil some point soon so I don't have another coil fail and hurt the drive ability. When the coils failed on my C3 they exhibited similar ignition breakup above a specific engine speed.

The idea of Die-Electric grease will not help as all it can do is slow down corrosion on the connections. Die Electric Grease is NOT CONDUCTIVE and will not enhance the connections in any way. If the connections are dirty clean them with a pencil eraser or consider DeOxIt as the DeOxIt will clean off corrosion on the connectors.

Once in the past I experienced my first coil failure so I pulled my old Coil from the original factory Transistorized Ignition System and it was able to bail me out until the new coil came in. It seems interesting that a 55 year old coil would last but the newer MSD coils don't, I think China is part of the issue as they make a lot of those parts today. I believe that mounting the coil away from the HOT intake manifold away from the vibrating of the engine might help in the long run.

 

Thanks. BTW - The "old" coil only lasted 1-2 years after the Sniper EFI was installed - and it was used that much since I had a lot of issues getting the Sniper properly programmed. What you are saying is the best explanation I've heard. Since you have the Sniper, did you experience any amperage issues? I'm using a 61 amp alternator and it doesn't' provide enough voltage at idle to use the headlights or WWs ( which doesn't bother me since the car is only driven in bright sunlight - but it should be fixed at some point). Thanks again.