Quick Coil Preference Question

H

hillbry

Member
Have a 71 Scout II 345 with the Holley curved point distributor and got a ignitor kit and want to get the corresponding coil to go with it. There are a few flamethrower coils which are in question but is the epoxy 40,000 coil the best option or is there a 45,000 option that is a better option.

Either way what is going to be the new gapping for the plugs and should I get a thicker set of spark plug wires?
 
With the ignition setup you have there is absolutely no reason to use any other coil than whatever you currently are running for a "stocker". It's good for around 22kv open circuit which is more than twice what that engine will ever be able to require!

If you are insistent that you need to change the coil, I'd never use any "epoxy encapsulated" version of a conventional coil. In fact, I know of not one single performance aftermarket coil that is really worth crap, I simply don't use 'em for multiple reasons. I keep new aftermarket replacement coils on hand here that cost me around $20 each.

If you eventually add a true capacitive discharge box to the system, then there are selective e-core coils that have some performance enhancements.

Using only a pertronix inside the distributor does not provide any greater "voltage available" than running either points or the Holley gold box trigger.

The outside diameter of the spark plug cables we normally use today on any similar vehicle is plain old helical-wound cables with an 8mm od insulation. Those run about 50ohms per foot of length. The actual internal conductor type from accel, msd, etc. Are all the same type material and can take any type of voltage/current that any ignition system can provide.

We always use a silicone-base terminal coating on each spark plug connector and at the distributor cap terminals, been doing that for more than 30 years.
 
Mm: quick question, 77 SSII, 345 2bbl, pertronix, 727tf, headers, truetracs front and back.

I have an excel coil (about 1 year old) that gets rather hot to touch in the engine compartment. It is supposed to be spitting out 40k. You saying that a regular stock coil is sufficient? You could be right. Maybe the coil is overkill?
I have been having problems with my engine dying recently when the engine gets hot. Could the coil be getting so hot that it is shorting out, thereby causing the engine to start missing and the finally dying? Symptoms similar to a carb starving for fuel, bad fuel pump.
Finally, how warm or hot should a coil be getting? Should you be able to put your hand on it, or does a coil naturally get real hot?
And then, what is actually inside a coil that would short out.

Thanks,
 
Michael is temporarily unavailable until further notice, so I'll take a stab. To work with the ignitor, your coil needs to be low in primary resistance. Your engine's cooling fan should be able to keep the coil as cool if not cooler than any other surface in close proximity. If it is very hot to the touch after a drive, something ain't right. Do you have a digital volt meter? If not, you should at least invest in a chinee cheapo from harbur fake toolz. If so, set it to measure ohms on the lowest setting...its the symbol that looks like headphones. You want the coil to be as close to room temperature as possible. Have all wire leads removed from the coil terminals. Red probe to coil +, black probe to coil -. Readout should be something like 1.5, 3.2 etc etc. In other words, a small number. Perform the test and report back with your findings.
 
If you're using an ignitor I product, you will need to use a coil with the proper primary resistance. Your accel coil May have too low resistance and might burn up the ignitor or lead to other ignition issues. If you look on page 49 of the pertronix 2010 catalog, they recommend a coil with 1.5 ohms of resistance. Only with the ignitor II and iii products can you get away with as low resistance as possible (~0.30 - which is where I bet your accel coil is). Usually, your best bet is to run a pertronix flame thrower coil matching the ignitor you're using.

http://www.pertronix.com/catalogs/pdf/ptx/2010/pertronix2010.pdf
 
Last edited:
I will check. In the meantime, I will put a stock coil back in and run to see if this is the problem. I need to check the resistance and will report back.

So a hypothetical: if the accel coil is cranking out 40k and the thread above from mm states only 22.5k is sufficient, where does the other 17.5k go? Is this causing the coil to overheat, or am I burning up the ignitor?
 
The coil only needs to put out enough voltage to jump the gap on the spark plug. So if it takes 10kv then that is all the coil make before being discharged.

With a hi-perf coil if the plug is disconnected now there is about double the voltage than the internal components are designed to handle looking for some place to go. When Chevy first created the hei units they were known to blow a hole through the top of the rotor right below the center terminal on the cap. Not tell me that that wouldn't be a tough problem to find.
 
Back in '95, the oem stock coil on my 304 became very weak, indicated by a very high primary winding resistance and small orange spark at the plugs. I ordered an msd blaster 2 coil (oil-filled, btw) from summit racing, and all has been well since.

I use a ballast resistor with it for my mallory unilite distributor/ignition unit.
 
You must log in or register to reply here.
Back
Top