New a4 owner hoping for some assistance

[hanleyclifford]

Originally Posted by stranded-sailor

I looked up resistance values for coil and found this

a 12 volt coil will have a nominal resistance of around 1.5 ohms give or take a couple of tenths. The secondary resistance should be at least 8,000 ohms and can go as high as 12 to 13 thousand ohms depending on the coil

Is the coil for the a4 different? I got this replacement coil at a car parts place. Looked at my old one and said this one would work.

He's right; it would work - IF it had the correct resistance in front of it. In fact just about any "12" volt auto coil will fire the A4 but buying the coil from Moyer Marine takes the guesswork out of the solution.

[joe_db]

Originally Posted by stranded-sailor

I looked up resistance values for coil and found this

a 12 volt coil will have a nominal resistance of around 1.5 ohms give or take a couple of tenths. The secondary resistance should be at least 8,000 ohms and can go as high as 12 to 13 thousand ohms depending on the coil

Is the coil for the a4 different? I got this replacement coil at a car parts place. Looked at my old one and said this one would work.

1.5 ohm coils will burn out. My auto parts place, being on an island, has 4 ohm coils for Atomic 4s, but 99.5% of them hardly understand old fashioned coils anymore. Moyer also has them

[stranded-sailor]

Ok. All good information. After tearing into this this afternoon I think its just time for a full tune up. Everything is wore some and plugs are obviously old. Coil reads good and getting power but no spark. Problem is I was hoping to leave here tomorrow night to get to a spot where I have better support. Only get the odd 24h with under 25kn winds and tomorrow nights one of them. If I'm understanding correctly this coil will work just not last as long as the right one? Maybe local parts store has cap and rotor button? And they should have plugs no problem.

[hanleyclifford]

Originally Posted by stranded-sailor

Ok. All good information. After tearing into this this afternoon I think its just time for a full tune up. Everything is wore some and plugs are obviously old. Coil reads good and getting power but no spark. Problem is I was hoping to leave here tomorrow night to get to a spot where I have better support. Only get the odd 24h with under 25kn winds and tomorrow nights one of them. If I'm understanding correctly this coil will work just not last as long as the right one? Maybe local parts store has cap and rotor button? And they should have plugs no problem.

Local parts store might even have a resistor for you. Worth asking. 2 ohm for starters, only has to carry 2 amps max

[joe_db]

What he said. Ask for a 2 ohm ballast resistor or somewhere around that like 1.6 ohms.
Like this:
https://www.amazon.com/Aramox-Igniti...s%2C120&sr=8-3

[Sailorsb]

Originally Posted by stranded-sailor

Ok. All good information. After tearing into this this afternoon I think its just time for a full tune up. Everything is wore some and plugs are obviously old. Coil reads good and getting power but no spark. Problem is I was hoping to leave here tomorrow night to get to a spot where I have better support. Only get the odd 24h with under 25kn winds and tomorrow nights one of them. If I'm understanding correctly this coil will work just not last as long as the right one? Maybe local parts store has cap and rotor button? And they should have plugs no problem.

I’m new to this forum, but in the photo it looks like there may be a cut in the insulation on one of the wires coming from the (+) terminal of your coil. If the conductor is exposed, it could short to ground.

Steve
Port Huron, MI

[joe_db]

The easy way is to hook it up and see if it works. Actually there is no other way to test the Pertronix that I know of.

[W2ET]

Steve (Sailorsb) pointed this out.

[stranded-sailor]

Originally Posted by Sailorsb

I’m new to this forum, but in the photo it looks like there may be a cut in the insulation on one of the wires coming from the (+) terminal of your coil. If the conductor is exposed, it could short to ground.

Steve
Port Huron, MI

Your correct there is. Has since been repaired. Thank you

[sastanley]

s-s - it's OK dude, that is how we all learn. You can use a 1.5Ω coil provided you have sufficient external resistance in front of it. I experimented quite a bit with different external ceramic resistors until I was satisfied. the ignition is likely fine, it is the coil that will get fried, but they usually come back for a while. The way you tell if that coil is fried is run the motor and if it goes 45-90 minutes and shuts off, the coil is toast. then it will cool down and run for a little while again.

edit - oops, i missed the entire 2nd page.

[stranded-sailor]

Originally Posted by sastanley

s-s - it's OK dude, that is how we all learn. You can use a 1.5Ω coil provided you have sufficient external resistance in front of it. I experimented quite a bit with different external ceramic resistors until I was satisfied. the ignition is likely fine, it is the coil that will get fried, but they usually come back for a while. The way you tell if that coil is fried is run the motor and if it goes 45-90 minutes and shuts off, the coil is toast. then it will cool down and run for a little while again.

edit - oops, i missed the entire 2nd page.

Yes, running 30 to 40 minutes was the issue at first. New coil which apparently is incorrect but I'm going to get a resistor for it. The last shutdown(which was after the new coil) I believe is a tune up problem, or atleast thats what I'm going to do next to eliminate it as the plugs and rotor button are very bad looking. Hoping that solves the issue, if not atleast its out of the way. Tks for your reply

[Dave Neptune]

The rotor and cap should be replaced at the same time. While you are under the cap be sure and give the C-advance a twist to be sure it moves freely and returns smoothly too.

Dave Neptune

[stranded-sailor]

I was just looking at the moyer site and see that there are two distributor caps which look identical. I do not have points, one cap says for ignitor systems. Would this be the one I want? Also my engine is a '72. Would this be a late model?

[sastanley]

I used the points cap that I had on hand, and used a sharp knife to open the cutout at the base a bit to handle the extra wire & rubber grommet which was absent in the points system. The early model Prestolites were smaller in diameter and I think had clips, whereas the late models are larger and screw down caps. As Dave said, make sure you have some light oil while you are in there and made sure the spring loaded advance works..The distributor shaft is actually two, one rotates inside the other to do the timing advance. You should be able to twist the shaft about 17 degrees (inner I think, been a couple years) and it should spring back with force and pop right back into place. It is easy to forget maintenance on this piece with EI because you aren't pulling the cap regularly to fool with points. If you can't get a fresh cap & rotor right away, some emery cloth or sand paper can clean up the contacts until you can replace cap & rotor.

[Borrowed Time]

I had this same issue when I converted my A4 from points/condenser to a Pertronics Electronic Ignition like that shown in OP's picture. I had intermittent shut downs happening and it about drove me crazy using coils from here and there. I finally broke down and bought Don Moyer's coil. It was quite a bit more expensive than what you will get from an auto parts store, but my random shut down problems ended the day I installed Don's coil. Oh and I have no resistor in-line, it is not needed as long as charging voltage is reasonable. It simple and it works beautifully on my A4. As for charging, I am using the original motorola alternator with a newer external voltage regulator after my old one died. I now charge below 14 volts and the system seems to be working great.

[sastanley]

Chris, It would be a couple interesting data points to know when running:

(+) voltage at the coil (be sure to use engine to ground, not (-) post)
(+) voltage at the alternator post
(+) voltage at the battery post

Many of us went thru this exercise way back on the forum, and had interesting results. Lots of our old boats see significant voltage loss if we have a cockpit mounted ammeter. I ended up removing mine and went straight to the batteries from my alternator and then adjusted my charge voltage to my personal preference (running an m5-197 adjustable regulator on my OEM Motorola)

This will also provide some fresh data for stranded-sailor to digest.

[Borrowed Time]

I'll check voltages this weekend and get back to you all.

[ndutton]

Pertinent information from the manufacturer of the electronic ignition is found here.