I am interested in going to an electronic ignition system. However, there is a lot to be said about a point system when it comes to diagnosing problems and stocking spare parts on board. Any reccomendations? What would I need to stock on board to be assured that I could get it back up and running if I had a failure? How dependable is the igniter system?
The Ignitor has proven to be extremely reliable.
The Ignitor has the benefit of coming with its own breaker plate, which means that you can remove the original breaker plate with the points and condenser still mounted and hang on to the whole assembly in your spare parts box. If you ever do suspect the Ignitor has failed in some way, you can simply remove the two little machine screws holding the Ignitor and its breaker plate in place and replace the points and condenser (still mounted on their plate as before).
As to my own opinion, I believe the Ignitor represents a real advantage in cases where access to the distributor is limited and/or a person simply doesn’t want to mess around with changing the points on a regular basis. – Updated: May 16, 2004
Removing and replacing a Prestolite distributor
If it is known for certain that the distributor has been previously installed in the best orientation, the distributor can be reinstalled with the rotor pointing in the same direction. However, if the “oiler” tube and the hold-down clips for the caps face in an awkward direction, you may want to start with step one:
1) Turn your engine over until you have the number one cylinder (nearest the flywheel) at top dead center of its compression stroke. This is most easily done with all the spark plugs removed so that you can turn the flywheel by hand. Hold your thumb over the first spark plug hole until you just begin to feel compression. At this point, the roll pin in the center of the flywheel should be roughly horizontal. Continue turning (counterclockwise) until the roll pin is vertical.
2) If your old distributor is still installed, remove the cap, and note the direction in which the rotor is pointing. It should be pointing directly aft. The distributor will work in virtually any orientation, but the oiling tube, distributor cap retaining clips, etc. will not end up in convenient locations.
3) Disconnect the distributor lead to the negative terminal of the coil, and remove the old distributor by removing the 1/4 X 20 retaining bolt holding it in place through its timing adjusting bracket.
4) Remove the timing adjusting bracket from the old distributor, and re-install it on the new distributor. If the new distributor came with an adjusting bracket installed, you can ignore this step.
5) Install the new distributor, making certain that the rotor ends up pointing in the original direction, or directly aft. Rotate the body of the distributor until the alignment notch is directly under the tip of the rotor. This will be the location of the number one spark plug wire.
NOTE: The following step only applies if an Ignitor (electronic ignition) is being installed.
6) Connect the red lead to the positive terminal of the coil, and the black lead to the negative terminal of the coil. This step is very important, since the Ignitor module is very unforgiving of reversed polarity.
7) If the distributor is being reinstalled after replacing points and condenser, connect the points lead from the coil to the negative terminal of the coil.
8) Connect the primary ignition lead from the “ign” terminal of the ignition switch to the positive terminal of the coil.
9) Connect a 12 volt (continuity checking) light across the positive and negative terminals of the coil, and with the ignition switch on, rotate the body of the distributor slowly and a small amount in each direction until the light is observed to be going on and off. Stop at the point that the light has just gone off, and tighten the adjusting bracket at the base of the distributor to hold it in this location. The point that the light has just gone off is the point that the spark will occur.
10) You should be able to start the engine at this point. After the engine is fully warmed up, and under load at your favorite cruise RPM, loosen the adjusting bracket and once again, rotate the distributor carefully a small amount in each direction to determine if the RPM increases. If the RPM does increase, tighten the adjusting bracket at the point of maximum RPM. If RPM stays the same, retighten the bracket, as the timing is already at the place where it should be. – Updated: May 16, 2004
Is it possible to reassemble a distributor's mechanical advance mechanism in reverse order? I have a later model (1974) Atomic 4.
It is indeed possible to install the flyweights in a Delco distributor upside down. In this configuration, the ignition will retard rather than advance. To be sure the advance mechanism is installed correctly, rotate the rotor against the spring return. You should only be able to rotate the distributor in a clockwise direction (for a slight amount into the spring tension). If you can rotate it in a counterclockwise direction, the flyweights are in backwards. – Updated: April 15, 2004
If my early model engine got out of time, how do I reinstall the Prestolite distributor?
If it is known for certain that the distributor has been previously installed in the best orientation, the distributor can be reinstalled with the rotor pointing in precisely the same direction. However, if the “oiler” tube and the hold-down clips for the caps face in an awkward direction, or if the orientation of the rotor prior to removal is not known, you’ll have to start with step one.
1) Turn your engine over until you have the number one cylinder (nearest the flywheel) at top dead center of its compression stroke. This is most easily done with all the spark plugs removed so that you can turn the flywheel by hand. Hold your thumb over the first spark plug hole until you just begin to feel compression. At this point, the roll pin in the center of the flywheel should be roughly horizontal. Continue turning (counterclockwise) until the roll pin is vertical.
2) If your old distributor is still installed, remove the cap, and note the direction in which the rotor is pointing. It should be pointing directly aft. The distributor will work in virtually any orientation, but the oiling tube, distributor cap retaining clips, etc. will not end up in convenient locations.
3) Disconnect the distributor lead to the negative terminal of the coil, and remove the old distributor by removing the 1/4 X 20 retaining bolt holding it in place through its timing adjusting bracket.
4) Remove the timing adjusting bracket from the old distributor, and re-install it on the new distributor. If the new distributor came with an adjusting bracket installed, you can ignore this step.
5) Install the new distributor, making certain that the rotor ends up pointing in the original direction, or directly aft. Rotate the body of the distributor until the alignment notch is directly under the tip of the rotor. This will be the location of the number one spark plug wire.
NOTE: The following step only applies if an Ignitor (electronic ignition) is being installed.
6) Connect the red lead to the positive terminal of the coil and the black lead to the negative terminal of the coil. This step is very important, since the Ignitor module is very unforgiving of reversed polarity.
7) If the distributor is being reinstalled after replacing points and condenser, connect the points lead from the coil to the negative terminal of the coil.
8) Connect the primary ignition lead from the “ign” terminal of the ignition switch to the positive terminal of the coil.
9) Connect a 12 volt (continuity checking) light across the positive and negative terminals of the coil, and (with the ignition switch on) rotate the body of the distributor slowly and a small amount in each direction until the light is observed to be going on and off. Stop at the point that the light has just gone off, and tighten the adjusting bracket at the base of the distributor to hold it in this location. The point that the light has just gone off is the point that the spark will occur.
10) You should be able to start the engine at this point. After the engine is fully warmed up, and under load at your favorite cruise RPM, loosen the adjusting bracket and once again, rotate the distributor carefully a small amount in each direction to determine if the RPM increases. If the RPM does increase, tighten the adjusting bracket at the point of maximum RPM. If RPM stays the same, retighten the bracket, as the timing is already at the place where it should be. – Updated: April 15, 2004
Installed new depth/speed instrument on my C&C 27 last summer. I experienced intermittent "cycling" of the instrument when the engine was running, especially after long periods. I think that the problem is radio noise from the alternator or ignition. Any suggestions on how to correct?
Before doing anything more serious, be sure that you are using resistor plugs. Resistor plugs are identified by the addition of an “R” in front of the part number. – Updated: November 21, 2003
I tried to remove the spark plugs on my boat. It looked like the previous owner had not changed them in a long time. I soaked them with penetrating oil for several days. However one of them broke off in the head. The part with the threads is still in the head. I tried an easy out but was afraid it was going to break without any success. Do you have a suggestion?
I hate to be the messenger of bad news, but (assuming that the “easy-out” option failed) it will almost certainly be necessary to remove your head to remove the broken spark plug.
On the bright side, once the head is off, it is an easy job for any machine shop to drill out the plug, and dress up the threads.
Given the value of an otherwise good quality head, you were wise to stop and think things over a bit before proceeding. Many folks have severely damaged a head before they call for help. – Updated: November 21, 2003
What is the recommended spark plug for the Atomic 4?
The original factory recommendation was the Champion J8. However, we prefer the Champion RJ12C. We would point out, however, that there are quite a few plugs that are reported to work very well in the Atomic 4, so if you have a particular brand of plug that is working well for you, there is no need to rush out and change plugs.
By way of background, the main difference between the J8 and the RJ12C is that the J12 represents the next higher heat range from the J8, and this increased heat range seems to help the plugs to run a bit cleaner in most of our engines. Some years ago, Champion left numbers 9, 10, and 11 out of their numbering system, but when we checked with the factory, we were informed that the increase in heat range between the J8 and the J12 was a modest one. They explained further that the operating temperature of a particular plug is increased primarily by simply thinning out the porcelain around the center electrode. Their explanation seems to make sense, since you don’t see a lot of difference when you look at the center electrodes of the two plugs.
The “R” designation means that the plug has internal resistance, which is very beneficial in preventing interference with electronic equipment as well as providing a slightly stronger spark.
The “C” designation means that the electrodes are made of copper. – Updated: November 4, 2003
What coil is recommended for the Atomic 4?
Most coils with an internal resistance of 3 to 4 ohms should work very well in the Atomic 4. The coil we sell in our online catalog (under the ignition section) has proven to be very reliable and trouble free on the Atomic 4.
In the unlikely event that your boat has had an external ballast resistor installed in its primary ignition circuit (somewhere between the ignition switch and the coil), you should select a coil with a lower internal resistance (approximately 1.5 ohms). The ballast resistor is a rather large porcelain device measuring about 4” long by 3/4” square, and it provides the additional 1.5 to 2 ohms necessary to bring the resistance within the primary circuit back up to 3 to 4 ohms. Coils which have a ballast resistor providing some of the required resistance externally tend to operate a bit cooler than coils with internal resistance. We have always been assured by manufacturers, however, that coils are designed to withstand the additional heat of internal resistance.
Manufacturers also point out that traditional metal-covered, oil filled coils tend to transfer heat somewhat more efficiently than solid epoxy coils. The fact that oil filled coils may feel quite hot to the touch is clear evidence that they are indeed transferring a lot of heat to the atmosphere (and to your fingers).
Unless coils are subjected to extremely high heat, physical damage, or oil leaks, they should have a life expectancy of many years. In many cases, coils last practically indefinitely. Some folks from very hot climates report that they have been able to improve their coil life somewhat by moving them outside of their very hot engine compartments. Prior to relocating their coils, they would have to replace them every year or two.
The increased dwell time provided by electronic ignition systems (approximately twice that of conventional systems) can cause coils to run somewhat hotter than those on engines with points and condensers. However, we have no evidence from our experience to indicate that coils used in electronic ignition systems fail significantly faster than those in conventional systems, nor do we have any indication that any good oil-filled coil (with at least 3 ohms internal resistance) will not work satisfactorily with electronic ignition systems. – Updated: November 4, 2003
What would cause my engine to have no spark?
In most cases, lack of spark (meaning a lack of discharge from the secondary windings of the coil) is caused by a breakdown within the primary (or the 12 volt) part of the ignition system. Except where noted, all of the following checks are made with the ignition switch in the “ON” position, and the points open.
Remember that most of the primary ignition circuit is external to the engine, and includes all of the wiring, connections and switches between the big positive battery cable connection on the starter solenoid, and ending at the positive terminal of the coil. For this reason, a good place to start troubleshooting is to determine whether or not 12 volts is actually making it to the positive terminal of the coil. If it is not, troubleshoot the circuit (first within the boat itself) to determine where it is open.
If there are 12 volts present at the positive terminal of the coil, check the engine portion of the primary circuit by checking for the presence of 12 volts between the connecting terminal on the points and ground (making sure that the points are still open). If there is no voltage at this terminal, there must be an open circuit in the primary windings of the coil, or in the short wire leading from the negative terminal of the coil to the terminal on the points.
If there is 12 volts present between the terminal on the points and ground, rotate the engine until the points are closed. Then flick the points open and closed with a small screwdriver. As you flick the points, do you observe a small spark as the points make and break contact with each other? If so, disconnect the secondary lead from the center of the distributor cap and hold the end of the lead about 1/2” from the cylinder head. As you continue to flick the points open and closed with a small screwdriver, you should observe a secondary spark between the coil lead and the cylinder head.
If you do not observe a small spark between the points as you flick them open and closed (as in the previous step), the points are not conducting and will need to be cleaned or replaced.
NOTE: The points not making contact with each other is a common cause of engines not starting in the spring, following a winter lay up. The problem is usually nothing more than a thin layer of corrosion, or spider web. Either problem can easily be dealt with by simply running a piece of cardboard between the points to “dust them off.”
If the entire primary circuit checks out without a problem and there is still no secondary discharge from the coil, the short lead from the coil to the center of the distributor cap could be bad. It is much more likely, however, that the secondary windings in the coil are short-circuiting to ground (meaning to the block) instead of coming out through the lead in the top of the coil. If you are stuck away from your home port with a bad coil, you may be able to make the coil work long enough to get home by removing it from the block and suspending it by some nonconductive string (away from any metal).
If the lack of spark is intermittent, refer to the entries describing techniques for troubleshooting intermittent problems. – Updated: November 4, 2003
My alternator is shot and I'm thinking about replacing it. Do you have suggestions on an alternator for the Atomic 4?
We have been using and marketing Mando alternators for several years with excellent results. They are pictured in the online catalog, in the electrical grouping of the overhaul section.
Like the Motorola 35 amp, which has been the standard alternator for many years, the Mando is a single output unit with a built-in regulator. In addition, it has a slightly higher amp rating (55 amps), does not need a separate wire to a 12 volt source to energize the fields, and it is much more forgiving of inadvertently switching the main battery switch through OFF.
– Updated: November 4, 2003
What is "dwell angle", and how do I measure it?
Dwell angle is a measure of the duration of time that the primary circuit of the ignition system is closed to energize the primary windings of the coil. It expressed (and measured) in degrees of rotation of the distributor rotor, hence the use of the term “angle”.
In actual operation, as the distributor mechanism rotates, the points (or electronic module in electronic ignition systems) are closed for a certain number of degrees of rotation, and open between these points. Simply as a matter of interest, this means that the total number of degrees during which the points are closed, plus the total number of degrees that they are open, will equal 360 degrees.
In four cylinder engines, there is usually ample time for the primary circuit to be open and closed (to energize the coil) four times during each revolution of the distributor, which makes the dwell value less critical than in 6 and 8 cylinder engines. In four cylinder engines, there is more of a concern over having too much dwell time (during which time the coil is energized) which can result in high coil temperature and premature failure.
In electronic ignition systems, the dwell value is fixed at approximately 50 degrees. In conventional systems, (considering the difficulty involved in checking and adjusting for dwell) most folks simply rely on the setting of the point gap to provide the proper dwell time. In the event that you want to check your dwell, here is a reprint from the ignition chapter of our service and overhaul manual:
CHECKING FOR PROPER DWELL ANGLE
The dwell angle specified for the Atomic 4 is 31 to 34 degrees for late models (Delco), and 38 degrees for early models (Prestolite). To check for dwell angle, proceed as follows:
1) Connect the dwell meter as per its manufacturer’s instructions: Generally one of two leads is connected to the positive terminal of the battery and the other lead to the negative terminal of the coil.
2) Start the engine and read the dwell angle (making sure meter is set on 4 cylinder).
3) Adjusting dwell on the Atomic 4 is somewhat of a trial and error process. If dwell angle is too high (points closed for too many degree of rotation), you will have to carefully reset your points to a slightly larger gap. If the dwell angle is too low, the points will need to be set slightly closer. Adjust the gap .002″ or .003″ at a time for best control.
4) Restart the engine and re-measure dwell angle. Repeat as above until dwell angle is correct. – Updated: November 4, 2003
Delco distributor breaker plate screw size?
The late model Delco distributor breaker plate mounting screws are 8-32 x 3/8″ pan head, steel, with a standard screwdriver slot.
What size are the coil terminal nuts?
The two coil terminal nuts are 10-32. They can be purchased at your local hardware store.
