Coil input information

[hanleyclifford]

Excellent recap, Neil. I nominate that post for Best of Best status.

[ndutton]

I left off a few things

Thanks Hanley, appreciate it.

Three more (brief) things I should have added:

For those with electronic ignition (and twice the dwell), what to do about it all?
I recommend modifying your ignition with the addition of a ballast resistor ahead of the coil to bring the sum of resistances (coil + resistor) to 4 ohms. This will cover applied voltages up to 16VDC. You'll need to know the resistance of the coil to select a properly sized ballast resistor.

OR . . .
replace your coil with a 4 ohm internal resistance coil, it will produce the same result.

OR . . .
confirm your existing coil has 4 ohm internal resistance.

Kelly,
Just a suggestion but if you're going to add a resistor, why not get one designed for an ignition application? Seems like a more reliable solution to me.

[Marian Claire]

This is when it really bites being 7 hrs from the boat. I want to do some testing on my coil. Wonderful post Neil. Dan S/V Marian Claire

[hanleyclifford]

What started out as a Kelly fishing expedition has turned out to be a very educational and useful thread due in large measure to our detail-oriented west coast A4 brother Neil Dutton. In my particular system where I have run the same coil for many years and a set of points for 1000 hrs at 10 - 11 volts, not thru the use of resistors, but rather by ganging up fuel and salt water pumps on the same circuit, it seems I have achieved the desired result by accident (should this be in the "Captain's Confessions" department?). A now identified by product has been the frequent replacement of the cheap, salt water pump cartridge made to run at less than 12 volts. The changes I am going to make in my wiring scheme are going to save money and pumps. Thanks to Kelly for getting us out of the barracks for this one!

[thatch]

"Above and Beyond"

Neil's post (#105) is the "Gettysburg Address" of A4 ignition systems. When you consider the fact that he has no ignition or electrical problems of his own, and has spent many hours of testing and posting to help others, I feel that this puts him in the catagory of "Super Hero".
Thank's, Tom

[dvd]

Boy am I glad I don't have any coil issues.

dvd

[smosher]

Neil, how do you have the ballast resistor wired in, looks like your coming off the + side of the coil to the resistor.

Where is the other side of the resistor going, maybe ignition switch ?

I'll hook mine up tomorrow.

Where can I get a cheap temperature scanner ?

I don't have a problem yet with the coil, but for the $ 20 sure is cheap insurance.

Steve

[ndutton]

Steve,

My resistor is installed just ahead of the coil. One resistor terminal gets the ignition wire from the switch, the other goes to the coil +. Here is the scanner I have.

Full disclosure:
Thatch emailed me a Pertronix diagram he uncovered that showed a ballast resistor. On their drawing the Ignitor module positive (red wire) is connected ahead of the resistor whereas mine is connected after the resistor. My way delivers lower voltage to the ignition module but I don't think it's any big deal. Pertronix specifies 8-16 volts range for their Ignitor so I think we're good either way. Without accurate measurement yet I estimate I'm running at 11 - 11.5 volts to the coil and module (after the resistor). I was unaware of their drawing when I installed my resistor, just did it without regard for the module. It's working fine though, starts instantly and runs smooth.

Stewing on it overnight I think I prefer the slightly lower voltage to the module. It might prolong its life. This is pure speculation. I could just as well start a thread next week on module failure, who knows?

dvd

In thatch's gracious post his comment that I wasn't having problems is correct but I'm not as magnanimous as he implies. With the coil failure experiences of many on the forum, I ain't waitin' around for it to happen to me. Something was clearly going on and it was high time we figured out what. We certainly weren't getting much help from Pertronix.

[sastanley]

Hi all...The weather here was (to say the least) crappy, however, we did take the boat out, with some guests, to a friend's beautiful waterfront home for his birthday party yesterday, and stayed aboard last night.

We motorsailed the entire way (left the dock at 4:30 PM yesterday & arrived just before sunset) and returned this morning. The weather was adverse, and of course, upwind, so mainsail up to help, but it really just stabilized things. We had a skinny channel to navigate thru, and actually bumped on the way out this morning as we rushed to get out at near high tide about 8:00 AM.

Yesterday morning, I put my 1.82ohm resistor (2.2ohm actual measurement) in front oh my 1.5 ohm (actual 1.7ohm) coil. The engine ran for 2+ hours yesterday into the wind at 1,900 RPM, and probably 3 hours today on the way home (did a little creek exploring). Absolutely zero troubles..I did measure the voltage yesterday after installing the 'larger' resistor..running voltage = 9.70volts at the coil..ahead of the resistor=13.2volts.

edit July 2012 - in reviewing this thread, I want to update this post to reflect my updated set up - I am now running 1.82 resistor in front of 3 ohm Pertronix coil..(the 1.5 ohm coil did not last long as the 1.82 resistor was not enough with only 1.5 ohm internal resistance & 14.2v from the alternator.) No problems with this current setup combined with my slightly higher than normal charging voltage this season.

Since we had guests, no cushions were pulled or access doors opened, no infrared thermometer, etc.. but the engine did great.

I'll try to get out again soon and get some temps on the coil while she is running to see if the resistor is helping to keep the coil cool. I also need to go swimming before it gets too cold and scrape the prop one more time.

Where is the sunshine on the East Coast?

edit - Neil..just read your post #105. Nice work, sir. +1

[joe_db]

Pertronix seems to have some ideas for low RPM with the Ignitor II unit. See the graph. Dwell is quite low at 1,000 RPM. It also can work with coil resistance as low as 0.6 ohms. I may get one of these units and I think Moyer needs to switch up to these as well.

See this also:
Features
Ignitor II systems develop up to 4 times more energy between 3000 and 5000 RPM than standard ignition systems.
High RPM performance is improved when used with the Flame-Thrower II super low resistance (0.6 ohms) 45,000 volt coil.
Adaptive dwell maintains peak energy throughout the entire RPM range, reducing misfires while improving engine performance.
Develops on average 4 times more available energy between 3000 and 5000 RPM, and 2 times more available plug voltage.
Peak current level is reached just prior to spark for maximum energy without the heat build-up, increasing coil and module life.
Adjusts spark timing at higher RPMs to compensate for the inherent electronic delay.
Senses startup and develops more energy for quicker, easier starting. Built in reverse polarity and over current protection shuts down the system, preventing component damage.

[smosher]

I connected the .85 ballast resistor today between the neg lead out of the ei and the neg side of the coil. I measured the coil and it is 3.8 ohms, its not a flamethrower, but a napa standard.

I also picked up a scanner and after 1 hr at fast idle the temp stabilized at 130.

I measured at the same spot as Neil,

Interesting note is that the engine temp at the coil holder is 120

Voltage drop across the resistor is 2.3 vdc, This makes the current flow at 3 amps.

Engine ran fine.

[hanleyclifford]

I don't know where the info on that graph comes from but the notion that standard points typical dwell for an 8 cylinder engine is 55 crankshaft degrees doesn't square with anything I've ever heard.

[joe_db]

See http://www.pertronix.com/prod/ig/ignitor2/default.aspx

I am thinking that if Pertronix took the trouble to engineer a way to vary the dwell to control coil heat with the Ignitor II, it must have been an issue for them with the Ignitor I.

I don't know where the info on that graph comes from but the notion that standard points typical dwell for an 8 cylinder engine is 55 crankshaft degrees doesn't square with anything I've ever heard.

[hanleyclifford]

Thank you for the link - now I see where the data comes from. The Moyer Manual specifies dwell for Prestolite distributors at 38 degrees and Delco 31 - 34 degrees, very different from that Pertronix source. I would caution members about relying on that link.

[joe_db]

Assuming that diagram is actually a 4 cylinder, the dwell is less than the point system until past about 1500 RPM and not as high as an Ignitor I until about 2000 RPM. I think the "typical breaker point system" line really should be labeled the Ignitor I, which is fixed at about 50 some degrees. Thus you have less coil heat below 2000 RPM. Also they seem to vary the connection instead of binary on-off.

Thank you for the link - now I see where the data comes from. The Moyer Manual specifies dwell for Prestolite distributors at 38 degrees and Delco 31 - 34 degrees, very different from that Pertronix source. I would caution members about relying on that link.