Pamco ignitions

so the old lady wants to buy me an early birthday gift. she was gonna pay to have the tank and side covers powder coated... but i'm not in any rush to do the prep work required. i was messing with points today, trying to get the ignition timed, and after the engine backfired so hard it blew my carbs off it dawned on me: "an electronic ignition sure would be nice". if i went electronic i'd definitely go Pamco.

what i'm wondering is if there is a huge performance increase between the various kits Mike's offers: standard, high output, and the ultimate high output?

any input is appreciated

pa23driver,

PA23...that's an Aztec or Apache, right? I flew a Cessna 337 Skymaster for 20 years. Enjoyed every minute of it.



I guess we should start by defining performance. As you go from the standard coil to the Ultimate coil, the coil voltage goes from about 37,000 to 82,000. By comparison, the stock points coil produces 10,000 on a good day when it was new, so you will get more than three times that voltage just with the standard coil.

Higher voltage results in several advantages:

1. 37,000 volts at 14.5 battery volts will still produce 20,000 volts when starting. Faster starts and less wear and tear on the starter, battery and alternator.

2. All of these coils produce a longer spark duration than the stock coil. Longer duration means more of the mixture is exposed to the spark, resulting in a larger "kernel" of initial flame that will ignite more of the mixture, resulting in greater efficiency, more power and better gas mileage.
3. The Ultimate coil with it's 82,000 volts means that you can increase the plug gap which also exposes more of the mixture to the spark to produce a bigger "kernel" of initial flame.
4. Higher voltage means more current in the spark across the gap. More current means a hotter spark. Hotter spark ignites more of the mixture, for more efficiency.
5. Higher voltage and more current also means that the spark can burn through fouling for a faster start and smoother idling.

Basically, the mixture going into the cylinder from the carb is not a perfect mixture. It consists of some air molecules, some fuel molecules and a few of each that just happen to be close enough together to form a true mixture with the ideal ratio of fuel and air, so the larger and hotter and longer lasting the spark, the more likely that more of the mixture will be ignited to form a "kernel" of flame that goes on to ignite the rest of the mixture charge.

Are you going to feel a surge of power with a 82,000 volt coil? You will if the rest of the engine is in great condition. The spark by itself cannot produce power.

Here is a table of some test runs I did with my stock '81/H to show the increased gas mileage with various coils and spark plugs. Gas mileage is a measure of the efficiency of the engine. Greater efficiency equates to more power, all things being equal:



You can also see the increased mileage with the installation of the Iridium spark plugs. The 6903 coil is the Ultimate coil.

These tests were done on a 60 mile round trip route over mostly highway roads with few stops at a steady 55 MPH, returning to the same gas pump each time for fillup and for accuracy of gas used.

honestly, the cheapest coil is the way to go....I had the green monster and it was great....but the damn thing started to arc through brand new boots at the coil tower....even saw it jump to the primary once. Before that i noticed it started alot easier though. right now for stock motor i find the stock coil more than adequate.

Pamcopete: you don't see too many of those skymaster's around any more, were you flying commercially? the pa23 i'm driving around is the aztec (pa23-250driver just doesn't have the same ring) i'm currently flight instructing in one right now, that and of course the cessna 172. Thanks for the info, pretty much what i was thinking, the gas mileage increase is pretty amazing though.

CDNTX650: actually arcing through the boot? damn, thats a lot of juice. i'm not running any mods other than cone filters and a flow-thru exhaust, and i'm trying to avoid rejetting, so i'm thinking the lower end coil might be the way to go

anyone else?

awesome knowledge bomb of a thread. good stuff.

pa23driver,

No, I didn't fly commercially. I had my instruments rating and flew about 200 hrs a year for my little company, PAMCO Electronics, Inc. Sold the plane in 2004

I have used all of the available coils from time to time for evaluation purposes. I ran the basic 17-6922 coil for a summer and I was happy with it. Engine starts right away. Coil stays cool. Just a good coil for everyday riding, and comes with built in plug wires, which is both good and bad because they are difficult to replace.

The Green Monster does have a tendency to arc to the gas tank due to it's large size and closeness to the tank tunnel. But it is a real flame thrower coil. The green monster will also self destruct if you leave one of the plug wires disconnected, however.

I am currently running the 17-6903 "Ultimate" coil, and I think it is the best of the lot. It produces 82,000 volts, runs cool, is smaller and easier to mount, the wire towers can be positioned clear of the tank and frame. I think that I get better overall performance with it, including instant starts, smother idle, more power and better gas mileage. I am currently running it with Mikes XS Performance Keihin Carb Kit with his reverse cone megaphone mufflers, and without exaggeration, the bike leaps forward when you give it the gas.

Oh, by the way...I do not make any money from the coils that Mike sells, so buy whichever one suits you.

Here is a pic of the 17-6903 "Ultimate" coil running with a 1" arc from a 14.5 volt battery:


Here it is running from 6 Volts to simulate a low battery when starting:


That's about a 1/2" arc, or roughly 15,000 volts with a 6 volt battery. The stock points coil only produces about 12,000 Volts with a 14.5 volt battery. The TCI will not work at all below 8 Volts and other after market systems need at least 9 volts @ 200 RPM to work. The PAMCO works all the way down to 6 volts @ 1 RPM, so that's why you get fast starts with the PAMCO.

I was running two green monster coils and one was arcing through the boot to the tank and shocking my hands and legs periodically and the bike ran like crap, it took FOREVER to figure out what the problem was because it was an invisible problem. No holes in the boot. Now I've got the dual output green monster and a Pamco, works great!

-j

I just noticed the boots on my Green Monster look like they are dry rotted a bit. Could this be because it is arcing through them. You can see in picture that it is really close to my gas tank. Should I be worried about this? I really love the setup though. One kick and it fires right up. I know the gas tank says it's a HD but it's mounted to my '79 xs650.

In my case, the rubber boot was actually touching the tank, which is probably why it was happening to me.

-j

If you mount tghe "Green Monster" like this, then the towers are too far away from the frame and tank to arc:

Mine wasn't even close to the tank, i had it mounted up front, probably and inch away from any metal. Like i said, i even saw it arc to the primary once. Stock voltage coil for the stock motor seems to be absolutely fine. Might try another greenie again with some die electric grease and some high voltage rubber tape from work.

Well, it is the "Green Monster" after all...a real flame thrower.