Help
I have a 1978 Super Sport El Camino with a 305 engine. In 2001 I had about 225,000 on it so my son rebuilt the engine in his high school class. Everything was replaced at that time. Everything is fine except that I am burning out the HEI capicator. I have put in 4 of them in about 3 1/2 years. The orginal one lasted me 25 years and 225,000 miles. I purchased all of the parts from NAPA (their good line). I asked them what could be causing the problem and I was told to check the voltage from the coil and see if it is more that 12 volts. If it is that is what is burning it. The voltage (tested at the heavy gauge pink wire) reads 14.5 volts. I have just replaced the distributor, rotor, cap, plugs and wires, and it stills reads 14.5 volts.
Does any one know if it should actually read 12 volts and if so what could be causing the increase.
Any help would be greatly appreciated as I am stumped
Thanks
Elamott

Its probably going to read the voltage across the Battery. If that is 14 + volts then that is what your going to read and it should. That is a good solid voltage. You could check the output at the Alternator but I wouldn't think that would actually be the issue.

Probably not what you want to hear but you can always purchase the MSD Super HEI Conversion kit, I did at recommendations of lots of other owners here, that will fix the problem the more voltage you have the better that thing seems to operate. You basically gut out the Distributor connect a wiring harness to the trigger inside the distributor run the wires to the MSD 6A or 6AL control module. No capacitor to mess with its all Digital state of the art stuff. You get rid of the "Coil-In-Cap" issue also. Your plugs will more than likely last twice as long and so will the plugs wires. You will have to get a more expensive set of plug wires that are spiral core and they'll run you from about $40 to $125.00 depending on which brand you decide to get. From what I understand you will also get a boost in power and fuel economy.

I have run a Msd-6a for 4 to 5 years now will no problems at all.

You could switch to an MSD but let's see if we can figuire out the problem that you have. The voltage reading of 14.5 is a little high but I don't think it's causing the problem. Maybe the capacitor is not attached securely and/or you have a bad ground to the capacitor. Make sure the capacitor is secure and then check the ground with a multimeter. Check continuity between capacitor shell and distributor body and distributor body and engine block.
With the HEI coil in cap there is a lot of heat in the distributor which could affect the longevity of the capacitor, but the module is more sensitive to heat and you're not having any problem with it.
As a long shot there could be a problem with the module causing the capacitor failures.
Hmmm.