The fuel system configuration is very important. The common setup will not work on the Atomic EFI. Please, see Diagram below:
There are three selections: Street/Stock, Mild, and Performance. Select the cam that best suits your application.
Note: If lobe separation angle (LSA) is less than 108°, you may need to go to the next larger cam profile. If cam duration is longer than 250°, the Atomic EFI will not be suitable for your application.
The operating fuel pressure is 30-75psi if you are using a PWM system (Pulse Width Modulated – Returnless system). If you have your own, regulated system, required pressure will depend on horsepower. Most vehicles will use close to 45psi, while vehicles pushing 600HP will need closer to 70psi.
Depending on horsepower, most vehicles will require 45psi unless you are putting out very high horsepower. There is a DTC (diagnostic trouble code) that indicates 100% injector duty cycle. If this condition is hit, you will need to increase your fuel pressure by a slight amount (5-10psi) and try again. Please see instruction page 6 for more information.
They are 80lb/hr @ 60psi.
The Atomic has been designed and calibrated to run on gasoline with up to 15% ethonal added. It is safe to run E-85, but the calibrations will be wrong. All fuel tables, including start-up, normal run, and transients will have issues with E85 fuel. Only attempt to run E-85 if you are familiar with the common corrections for these issues.
The fan drivers only support 1-2 amps, which means they will only drive the low current side of a relay. The fuel pump output can support 20 amps continually, without the need for a relay.
The Atomic is designed to run on 12 – 16 Volts. Voltage should not exceed 16 Volts, meaning a 16-Volt system with an alternator is not supported.
Magnetic points or standard coil negative will work, but not a hall-effect 5V signal. The signal out of any MSD distributor or MSD ignition control unit will suffice to supply an RPM signal for the Atomic. Note: An ignition control unit is required with most applications.
There is a 2-bar MAP (manifold absolute pressure) sensor, fuel pressure sensor, inlet air temperature sensor, throttle position sensor, and idle air controller (IAC). The throttle position sensor is a proprietary non-contact sensor that should not need to be replaced. The fuel pressure, MAP, and IAC may be replaced by sending the units into MSD if necessary.
The Atomic EFI throttle body can flow approximately 1000 CFM. The horsepower is not limited by air flow – rather it is limited by injector size.
The computer tells the IAC to open when it sees a 12V signal on the A/C input line, so it can open before the load is actually put on the engine, preventing the RPM from dropping. It does not actually raise the base idle RPM. It is factory preset and non-adjustable.
Under the "Initial Setup" screen on the Atomic EFI handheld, you will select "Enabled" for timing control. Next, under "Advanced Setup", find parameters to set a timing curve. The Atomic is limited to 44 degrees of total timing (including vacuum advance) due to the limits of a distributor.
Yes, you can set any base idle timing (minimum 500RPM) you would like, along with any total timing (minimum 1500RPM) you would like. In addition to this, you would be able to set a start RPM where the idle timing starts to advance towards total timing. You will also set the RPM at which timing reaches total timing. This will act like one of MSD distributor spring/bushing kits, but is not limited and can be set exactly. You cannot do a custom 3D timing table. No, the timing curve cannot be locked out. The base timing can be set as early as 500 RPM and the fastest advance curve will end at 1500RPM.
There is no start retard setting. However, if the Atomic is controlling ignition timing, the idle timing setting entered in the system will be used during starting. If idle timing is set to 10 degrees that is what timing will be during cranking. For example, if the engine needs a lower timing for cranking, you can set your idle timing lower (i.e. 5 degrees) by beginning the timing ramp at 500RPM with total timing at 35 degrees at 2000RPM. This will create a retarded start with 2 degrees of advance 100RPM through 2000. At an 800RPM idle, ignition timing will be 11 degrees. This is one example of the many options available. Always find the settings that will work best for the particular engine.
There is a selectable vacuum advance from 0-15 degrees. It maxes out below 16” Hg manifold vacuum and is completely gone by 7” Hg manifold vacuum, so it acts like a normal vacuum pot, only the total amount of vacuum advance is user adjustable, whereas the rate of advance is non-adjustable. By setting the vacuum advance to 0, the vacuum advance is disabled.
The Atomic EFI has idle timing control, since it is much faster than an IAC. The IAC is slow in responding to RPM changes compared to controlling idle speed through variations in timing to help maintain the idle RPM target. If you notice the idle timing jumping around, do not be alarmed, it is a normal function and will go away as soon as you touch the throttle.
The Atomic EFI will support engines with as at least 100ci to 800ci (maximum).
Injector size cannot be changed. If you are using your own system with a regulator, fuel pressure can be changed. A low-horsepower engine would benefit from using a fuel pressure regulator and setting the fuel pressure lower. MSD has successfully tested a 305cid engine with 200 horsepower using the PWM system and the air fuel ratio was fine at 500RPM.
There are only a few things that must be changed between combinations. Basic setup: engine displacement, number of cylinders, fuel pump type (return or PWM), idle RPM, rev limit, timing control, and three camshaft type selections (street, mild, and performance). Advanced setup: fans (separate on temp for both fans), AFR targets (idle, part throttle, and wide open), ignition timing (curve settings), and pump squirt (0-100%).
The unit will compensate for altitude changes if you go above 50% throttle and are between 1200 and 3000RPM. You can also cycle the key to the off position for 3 seconds, which will have the same effect.
The Atomic uses a fuel cut-off rev limiter.
Yes. Cold start conditions will be automatically compensated and will decay out as the engine warms up. By the time it reaches 145F, idle speed and fuel compensation are completely removed.
No, it will not hurt the unit. However, the WBO2 sensor will be drawing current the entire time for its heating plug. (Note: The O2 sensor will be hot if the key is left in the on-position. Care should be taken to avoid burns).
The Atomic must receive one pulse per combustion (4ppr on a V8).
If both fans are on, the fuel pump is at full capacity, the IAC is moving, the injectors are at their maximum, and the input voltage is around 10V, it can draw as much as 30 amps. Normal operation will be approximately 14-18 amps.
No, the Atomic EFI doesn’t have a built-in ignition driver and must be used in conjunction with an ignition box or a Ready-to-Run style distributor. Points and HEI distributors also need an ignition box to operate the Atomic.
No. The annular rings on the Atomic throttle body are designed by MSD’s engineers to work as special injector nozzles. The rings are not in a venturi and at no time does the fuel get pulled out because of low pressure. They help to spread the fuel out and have been shown to improve per cylinder fuel distribution. Even cylinder distribution, like that from a carburetor, helps make more consistent high rpm horsepower.
With a large pump the maximum output of the Atomic is 625 HP. The limiting factor is the injector size. The Atomic EFI utilizes four 80lb/hr injectors.
The Atomic fuel pump should always be mounted as close to the fuel tank as possible. Using a return style system is less vital, but a closer mount will aid in keeping the pump cool. Using a returnless style fuel system is vital for the pump to be as close as possible. With this system the pump must be within four feet of the tank, preferably two feet or less. The pump should always be at or below the bottom of the tank. The pump should be plumbed with the supplied 3/8” ID fuel line from the tank.
The fuel pump is a “pusher” pump only, which is what creates the limits on mounting options.
The can extensions cannot exceed six feet in total length.
The Atomic EFI utilizes shielded CAN and magnetic pick wires, which help cut down on noise interference. Still, the wiring from the Atomic EFI should not be routed in close proximity to the spark plug wires.
The Atomic EFI can withstand underhood temperatures in excess of 200°F and as low as 0°F.
The units are potted and are resistant to water intrusion, although should not be immersed. Normal motor washing should be fine, but never point a high-pressure water source directly at electrical devices.
Yes, with the addition of an MSD PN 6010 box, it can handle the fuel delivery, but not individual coil spark. If you are running a front mount distributor and single coil, you will be able to use timing control with an ignition box.
Yes. If you are running ignition timing control through the Atomic, a number of other small devices are required.
Yes, there is a ported vacuum outlet on the throttle body. Customers can still use a factory distributor vacuum if desired.
The handheld will display a DTC (Diagnostic Trouble Code) for the sensor. The engine will be allowed to continue running, but will use only the existing fuel tables. Fuel table adjustments or self-tuning will be deactivated.
The Atomic comes with default Air Fuel Ratios that should be sufficient for most street based engines. However, if a change in AFR is desired, the settings can be found in the “Advanced Setup” on the handheld controller.
An Air Fuel Ratio is the volume of air per each unit of fuel put into the engine. 14.7 units of air per 1 unit of fuel is “stoichiometric”, meaning there is the exact right amount of air available to burn all of the present fuel. A lower AFR number means there is less air to match the fuel, and therefore the engine will run “Richer.” Oppositely, a higher AFR number means that there is more air to match the fuel and the engine will run “Leaner.”
No. The Atomic EFI will not accommodate differently sized injectors.
No, not at this time. There are a number of changes that will need to take place before this is an option.
No, the injector duty cycle will still max out.
No. The Atomic EFI is not UL approved at this time.
The only service parts available are caps, rotors, modules, gears, and curve kits.
There are many things that could cause this issue. The top offenders include using the wrong size of a fuel pressure regulator, not using a return line, or having a return line that is too small. Other causes could include using too many 90° elbows, an improperly sized fuel pump is the wrong size for the engine horsepower, or using a return line out of the pump.
Yes, there are two (2) choices of kits to choose from when purchasing an MSD conversion kit. First, you will need to know what kind of distributor you have now. The kits are called "E-Spark" conversion kits or "Unilite" conversion kits.
There are two types of Mallory HEI distributors: 75 series and 85 series units. The 75 series HEI uses a module with a rev limiter - module part #699. The 85 series HEI uses the module part #607. Note: Pick up coils for the HEI distributors are not available as replacement parts.
The green wire connects to the negative (-) coil terminal. The red wire connects to the positive (+) coil terminal, and the brown wire connects to a good engine ground. The brown wire must be ground to the engine.
Note: The lack of a ballast resistor will cause this type of spike. If the voltage only drops down to 3-4 Volts, this will produce a weak spark: too weak to run engine and the module, will need to be replaced.
All Unilite distributors need coils with a minimum amount of 1.4 Ohms primary resistance. Coils are 12 Volts; however, they do have different amounts of primary resistance, which is measured in Ohms. You can still use a coil with less than 1.4 Ohms, but you must install a ballast resistor (Mallory #700) between the coil and the distributor, install on red wire coming out of the Unilite distributor. It is important to know that the Unilite distributor will work initially on the engine with less than 1.4 Ohms, but not for long. It only takes a short period of time to burn up the module using a coil with the wrong resistance. When you select a coil for any high-power CD ignition box like the Mallory Hyfire CD boxes, the Mallory Hyfire CD boxes must always use a coil with less than 1 Ohm of primary resistance.
Multiple Spark Discharge. It's a patented design that fires the spark plug multiple times, every time the unit is triggered.
Easier starts, more horsepower, and better throttle response are the expected results from an MSD capacitive discharge ignition, whether it's an analog or digital system.
With the multiple spark discharge of an MSD ignition, it is finally possible to completely ignite the air/fuel mixture in the cylinder, giving you more horsepower. In a 2-stroke engine this is important. When you suddenly give the engine "the gas" after idling, the engine will bog down. This is the result of a weak factory ignition trying to burn off the excess fuel that has built up in the cylinder. The factory ignition's weak spark can't do the job. The MSD ignition has a hotter spark to start with, and along with the multiple spark discharge, an MSD ignition will thoroughly ignite the air/fuel mixture.
With an MSD ignition you can run a wider spark plug gap than you would be able to with a factory ignition. The MSD ignition has a higher voltage output and can jump the spark plug gap easier. As an example, if you normally would run a .028 inch gap on your spark plug with a factory ignition, you could run a .032-.034 inch gap with an MSD ignition. There are variables that will affect the gap size: the higher the compression - the smaller the gap; the hotter the output of the ignition - the larger the gap, etc.
The flywheel no longer charges the battery. Usually the flywheel on a total loss system has been replaced with a lightweight aluminum flywheel, without the charging magnets. Quicker acceleration is the main advantage of a total loss system since you have lightened the moving mass on the end of the crankshaft. The drawback is that you have to keep an eye on the charge level of the battery - and check how many times you use the starter (a big drain on the battery), plus, how long you are out on the water. Figure about 4 to 6 hours of ride time starting off with a fully charged battery that has a 17 amp-hour rating, depending on how many times you use the starter.
TDC is where the piston reaches its highest point in the cylinder. It is the foundation for accurate timing. To find TDC, remove the spark plug and use a plunger depth gauge to judge where TDC is. If you don't have a depth gauge, place a screwdriver through the spark plug hole until the screwdriver rests on top of the piston. Turn the flywheel until the screwdriver reaches its highest point, make a reference mark on the flywheel and a reference point on the case. Then reverse the rotation of the flywheel, allowing the screwdriver to lower down and come back up again to its highest point. Make another reference mark on the flywheel. If the two points match up, consider yourself lucky because you have an accurate crank/connecting rod/piston assembly. If the two marks don't match up, pick the point exactly between your two reference marks (using the points closest together) - this is true TDC.
The main advantages of digital ignition are: accurate timing, smaller ignition box size, full access to the timing curve via dip switches. Plus, you can change the initial timing at the MSD box electronically, instead of moving the trigger around physically (because there are fewer components to fail).
RF noise stands for radio frequency noise. It is generated by spark plugs when they spark, and on motorcycles by points. RF noise causes CD ignitions to run erratically if they aren't shielded. A good way to lower RF noise is to use a good set of RF suppression spark plug wires - like an MSD 8.5 mm super conductor wire or MSD 8mm Heli-Core wire. The super conductor uses a special winding procedure with a ferro magnetic impregnated center core that is an effective RF suppression spark plug wire. In addition to using good spark plug wires, make sure that all grounds are good and clean. If you still have RF problems, shielding the ignition or moving it away from the RF source helps reduce interference.
In most cases, it is usually due to a bad ground or no ground at all. Check all connections. Here are a few things you could check: make sure the ground wire is securely attached; that there is no paint under the ground wire; the connectors have good secure connections; there are no breaks in the wires; the battery is fully charged. Check for a bad on/off switch in the ignition box. You could have a bad coil, and switching it out for a coil that you know is good, is the fastest way to determine whether a coil is the culprit. Perhaps, you have a bad triggering device. Check it by removing the spark plugs (leaving the spark plug wires on) and grounding them to the engine. Next: clip the two green trigger wires coming out of the engine, and repeatedly touch the 2 wires going to the ignition box together. Make sure the power to your ignition is on. You should get a spark or the LED (if equipped on your MSD box) should light. If you get a spark, then the trigger is bad. If the LED light turns on and there is no spark - then either you have a bad coil, (a) bad spark plug wire(s), or (a) bad spark plug(s).
A rev limiter does just what its name implies: it limits the revolution speed of the engine. Why is this important? If you have the throttle wide open on a watercraft and it comes out of the water, there is no load on the engine. The engine will dangerously zoom up in speed past its intended design and physical limits, possibly destroying itself. On a motorcycle if you have the throttle wide open and miss a shift, the same thing happens: a rapid increase in rpms, possibly destroying parts. A rev limiter is placed in the electronic circuitry that prevents the engine from over-reving. At a preset rpm - say 7,000 rpm - the rev limiter engages. Once the engine reaches 7,000 rpm, it interrupts the signal to the coil, alternating on/off, slowing the firing sequence, and preventing the engine from rapidly shooting up in rpms. Factory rev limiters are generally set at low rpm levels. If you have modified your engine, you may not notice any performance gains due to the factory rev limiter's low rpm limit, which is why you would use an MSD rev limiter. With MSD parts you can set the point, where you want the rev limiter to limit the engine's rpm.
Only if the engine is currently being held back by the factory rev limiter. You never want to set the rev limiter's rpm cut-off point too high - serious engine damage could occur.
Water is injected into the expansion chamber at specific rpm levels, this alters the sonic wave in the pipe. The water molecules directly affect the sonic wave properties, modifying back pressure deflection. You want the water to be injected at low to mid range rpms, and to be tapered off before your engine enters your upper rpm levels (leaving enough water to prevent any rubber couplers from melting). At 3,000 rpm the MSD pulse width modulated (PWM) switch turns on the water, by gently pulsing it on and off, then (at a rpm you preset) it will flow a steady stream of water. At the rpm preset by a user, the water starts pulsating on and off again, as the rpm rise, the volume of water decreases until the shut-off point is reached. There are no abrupt changes in power with the MSD PWM switch… as though you are hitting a pipes powerband. With the water gently pulsing on and off, instead of suddenly on and then suddenly off, you avoid the unwanted pipe "powerband" effect.
The primary benefits are low- and mid-range power increases. To also gain top end performance you could restrict the water flow in your pipe's factory cooling system, and use the MSD PWM switch to not only tune the pipe, but cool it at the same time. This is tricky because if you restrict the factory water cooling too much, you could melt the rubber couplers.
Whether for motorcycle use or watercraft use, each MSD digital ignition is optimized for a particular vehicle. Obviously, a full technical explanation of correct ignition timing for each individual engine would take up too much room here. A broad overview of how to arrive at a timing curve is shown in the guide below.
General Tuning Tips:
The main difference is the stability of timing. In most cases the generators are driven by a drive system from the block in a single or dual configuration. To provide clearance the drives are designed with an offset driven by a belt arrangement or a set of gears. Belt stretch or backlash can affect timing accuracies as well as the cam to crank drive, suffering from the same problem. This theory was unproven until RacePak developed their newest software that can monitor timing during a run.
Here MSD has a run showing the difference in timing in the generators vs. crank triggers. Notice how much the timing changes with the generator and how much smoother the timing is on the crank triggers. With the timing moving that much from base timing it explains some of the catastrophic failures.
This is a common question that is affected by other outside sources like:
Crank trigger wheel diameter: (Smaller vs. larger, larger being better because of higher magnet velocity).
Starter type: Block mounted vs. external (blower mounted).
Battery voltage: 12 Volts - 24 Volts (block mounted) 36 - 48 Volts (external starters).
Induction: blown vs. non-blown (blower more engine drag especially when restripped).
Typical air gap should be between .040 to .080, the low side is deemed by crank flex, and the high side is hard starting. If the engine fires up repeatedly, that can ensure the air gap is correct, and crank flex has been accounted for.
Air gap should not have a performance effect of the magneto system, however it has been noted that an excessive air gap can create a timing offset in the Race Pac data recorder by as much as 2º, depending on the air gap.
The purpose for the capacitor is to buffer the action of the "ON/OFF" switch to the battery in a monetary open condition due to severe tire shake or vibration. With the capacitor in place, the retard box would never see the open condition, if it did, the entire ignition system would lose power (shut completely off) and reignite again, possibly resulting in engine damage.
The minimum voltage will be 5.0 Volts to as high as 18.0 Volts. Keep in mind that other devices connected to the battery (other than the Pro Mag Timing Retard and Six Shooter) like the air switches that can draw more current than the Pro Mag Timing Retard and Six Shooter. One good test would be to monitor the voltage with a meter and trigger, the switches or timers via the WOT switch and watch the voltage.
The Pro Mag Timing Retard is 30º. This is because of rotor phasing, any more than 30º will result in a crossfire in the generator cap. Older Timing retard system that uses retard chips is also 30º maximum.
The Pro Mag Timing Control was initially designed with a maximum of 15º of retard, but at the racers request MSD has pushed the unit to 30º of retard. By doing this the calibrations have changed slightly from 15º to 30º, here are the values: 16º = 16º, 17º = 17º, 18º = 20º, 19º = 21º, 20º = 22º, 23º = 23º, 24º = 24º, 25º = 25º, 26º = 26º, 27º = 27º, 28º = 28º, 29º = 29º, and 30º = 30º.
These are offered in a limited quantity.
Spark plug wires are consumable like oil in the engine, so they should be changed on a frequent schedule that is determined by how often they run. A routine schedule of cleaning, inspecting, and checking the resistance of the wires should be done as a routine maintenance program of the vehicle. Some teams even keep a logbook of the resistance of when the wires were built to compare after running.
Some of the most common problems can come for the actual wire crimps that can be resolved by re-crimping the terminals or replacing them. The terminals are designed as a conductor crimp, so the conductor does not have to be bent over, which leads to a fracture or damage of the conductor, making it can read a higher resistance than normal.
The resistance should be 40 to 50 ohms per foot once the measurement is noted that value should not change. The only other facture that cannot be checked is the outside jacket, other than cleaning, and a visual inspection looking for abrasion, cuts and pinholes, the jacket will deteriorate in time due to the amount of energy being transferred through the wires.
The coil wire should be replaced often as it gets hit 8 times more than the other wires. Big budget teams replace wire set about every third race, while most others would replace them every 6th to7th race. There really is no gauge as to how often to replace the wire set. Remember, the wires are the actual delivery system of the spark energy to the spark plug that will affect a performance of the engine if not up to par.
This is a tough question to answer. There are only two reasons to replace coils when one is "Open" or has a shorted winding. In either case most can be found with a simple L.C.R. (inductor, capacitance, and resistance) meter. Notice that there are several numbers inscribed on the back of all coils.
One set is the date code (which had been changed to an easier method to read) and the second and third sets are the inductance values of the coils. In this case the numerical value does not represent any form of performance, like 709 vs. 899. These numbers are inductance values of the windings. These numbers are used to monitor a change within the coil. Keep in mind that these numbers are relative to the meters being used, several variables can account for the values: coil temperature, lead length, and meter model and meter frequency output. So if you purchase an LCR meter, these numbers will differ slightly from actual numbers on your coils. Once you acquire a meter, it would be wise to log these values and periodically check them to see if they have changed. Theoretically, once a coil is built and has run successfully down the track, it should never fail unless due to exterior damages.
In the beginning (1994) MSD coils were capable of extremely high voltages. The coils were capable of 55,000 Volts to 60,000 Volts, as time passed MSD found that these voltage capabilities were unnecessary and were resulting in a high yield of coil failures prior to shipping. MSD redesigned the coils limiting the output voltages to 45,000 Volts. This resulted in cooler running coils that were not capable of destroying themselves, yielding higher percentages of higher quality coils.
Prior to purchasing a set of coils they have already met several of MSD quality benchmarks. One of the outstanding tests lies in checking whether the coil can run for 5 minutes at 1800 RPM without a coil wire attached, this test is performed 3 times before arriving the packaging department. This is to test the quality of the potting material, assuring that porosities or air bubbles are not present. In most cases if either are present, the coil will fail prematurely. Eventually, coil usage will degrade coil life or performance, unfortunately translating this into a number of passes, races or years is difficult to determine.
In most cases it due to "Cranking RPM" or lack of RPM, the Pro Mags must see a minimum of 200 to 250 RPM to start. There are several variables that can contribute to a "NO Start" situation:
If the crank triggered the excessive crank pickup air gap (See "What's the correct air gap on the crank trigger pick (sensor)?"), insure that the starter is of a hi-torque type and that the batteries are fully charged. Checking battery voltage while cranking will insure batteries are fully charged. In some cases 16 to 18 Volts can aid a faster cranking speed. A word of caution: Not all starters can tolerate higher voltages and most block-mounted starters should not exceed 18 Volts.
A newly restriped blower can have enough friction to lower the cranking speed, try spraying silicon spray to lubricate the rotors. If that doesn't work, remove the blower belt (for testing purposes) and check for spark, this should free the motor up enough that if you do get spark, your cranking speed is too low to start the engine with the blower. If you do not get spark, remove the spark plugs and crank the engine again. (With the plugs removed, the engine will spin quickly). If still no spark, check the following:
Inspect all connectors to insure the pins have not back out and insure that the "grounds" are correct.
There are several ways to troublesshoot the system in a "NO SPARK" situation:
It sounds like the tachometer is connected to the 8132 Tach converter that is connected to the coil. When the rev limiter is active, it randomly drops cylinder by not lighting certain cylinders. The coil then does not spark on those cylinders, so the Tach converter does not generate a tach signal for the tachometer causing it to jump around.
One way to eliminate the tachometer jumping is the use of MSD Pro Mag Timing Retard that has a tach output. This unit will insure smooth tach trigger during rev limiting, because it not connected or depending on a coil signal.
Again, these parts are a consumable part of the ignition system and the power level that we're running at these parts will wear at a higher rate than non MSD magneto products. Typical wear will have a burnt or worn edge that's not as crisp or sharp but should not hurt performance. The life of a cap and rotor on a 44-amp system will shorter vs a 12 or 20 amp system.
The biggest difference is that the majority of factory ignitions are inductive ignitions. Inductive ignition systems are used owing to their simplicity and inexpensive production. For factory applications these ignitions are adequate, but when it comes to gaining performance, factory inductive ignitions fall short.
The primary weak link of a factory ignition is explained by the fact that the coil serves double duty. The coil must act as a step-up transformer to create a higher voltage spark. Plus, it needs to store this power until the ignition is triggered. As engine rpm increases, there isn’t enough time to completely step up the voltage before the ignition is triggered, resulting in a weaker spark. This low voltage spark may not be enough to light the fuel mixture in the cylinder, which will result in a misfire and loss of power.
ACD ignition, like an MSD 6 Series, is capable of producing full power sparks throughout the entire rpm range. It draws its energy directly from the battery where a custom wound transformer steps it up to over 460 Volts. This voltage is then stored in a capacitor until the ignition is triggered. At this point, all of the voltage is dumped into the coil where it is transformed into even more voltage, anywhere from 30,000 - 45,000 Volts, depending on the coil, which is sent to the distributor and finally to the plugs.
The ability to produce high power sparks throughout the entire rpm range of your engine is why you need a CD ignition. The payoff is complete combustion of the fuel mixture, which results in more power, increased throttle response, smooth idle, quick starts, improved economy, and reduced plug fouling.
All engines will benefit from a CD ignition but when you’re planning engine modifications, the need for an MSD ignition increases. In particular, if you’re planning these types of engine modifications, you should install a CD ignition to:
Conventional CD ignitions supply one spark of intense energy but for a short duration (time). An MSD uses multiple sparking technology to take advantage of the quick rise time and power of a CD ignition by producing a series of sparks. More sparks equal more heat in the combustion chamber, resulting in the complete combustion of the fuel mixture, which produces more power. At lower rpm, there are many benefits to multiple sparks, including a smooth idle and improved throttle response. Plus, the spark series prevents fouling plugs or fuel loading up in the cylinder when air/fuel distribution is poor.
The multiple spark series of an MSD ignition control lasts for 20° of crankshaft rotation. At lower rpm, for example 1,000 rpm, there is plenty of time to fire the plug a number of times to ensure ignition of the fuel mixture. As rpm increases, the piston travels up on the compression stroke faster, resulting in a shorter amount of time available to fire the plug, so the number of sparks that occur decreases. By about 3,000-3,300 rpm, there is only enough time to fire the plug once. From about this rpm range on, an MSD ignition control delivers one intense, full power spark.
The spark plug is the point in the ignition system where electrical energy is converted into heat, consequently. The larger the gap the greater the amount of heat available to light the air/fuel mixture. However, too large of gap combined with increased cylinder pressures can put excessive pressures on the initial voltage needed to ionize (cross) the gap. Finding the optimum plug gap for your application is best determined by experimentation because there are so many engine variables to consider.
An MSD ignition control has enough output power to consistently fire wider spark plug gaps on a performance engine. As a starting point, follow the engine builder’s or manufacturer’s recommendation for the plug gap. With that, you can experiment with increasing the gap until the best performance is found.
As a rule of thumb, it is recommended to increase the plug gap by .005” - .010” followed by testing and tuning. Keep in mind that larger spark plug gaps also place increasing demands on the secondary portion of the ignition system, including the distributor cap and rotor, coil wire, and spark plug wires. They should all be in top condition and checked periodically during the race season. Remember that electricity takes the path of least resistance to a ground, so if the gap is too large, the spark may short to another point with less resistance.
The battery is the fuel tank for the ignition system (magnetos excluded). When it’s empty, there is no electrical power available for the ignition system to convert into heat at the plug gap. In long duration racing events such as circle track racing, an alternator is highly recommended. In drag racing, a charging system is not a complete necessity as long as you have a good battery and charge it in between each round. Also keep in mind that electric fuel and water pumps, fans and solenoids eat up a lot of current as well.
Race cars without charging systems must have a battery with a large enough capacity to power all electrical parts. For example, an MSD 6 or 7 series ignition consumes approximately one amp per thousand rpm, so at 5,000 rpm, the MSD alone is using five amps. An MSD is designed to produce full power sparks with a supply voltage of 10 Volts, but if the supply drops below that, ignition output will suffer.
An MSD can be used with 16-Volt batteries, but no performance gain will occur because the output power of the MSD is regulated. The advantage of a 16 Volt-battery is increased electrical capacity.
MSD does not have a module to replace the breaker points system in your factory distributor, however an MSD ignition control will work great with a points trigger ignition. In fact, if you replace the points when you install your MSD, you’ll probably won’t have to replace or adjust them for years!
The MSD’s trigger wire connects directly to the breaker points wire so when the points open, the MSD is triggered. Since the MSD’s capacitor is responsible for sending the spark energy to the coil, the points are only used as a trigger reference signal. With this connection there is very little current crossing the points, so the wear is nominal at best. Also, the MSD controls the dwell, so the adjustment of the points is not that critical either. This setup works great with street cars and budget racers, but when you begin stepping up performance more and more, the need for a quality distributor comes into play.
MSD’s Pro-Billet distributors are engineered to deliver precise trigger signals, and provide accurate distribution of the sparks. A magnetic pickup is used to trigger the ignition. Unlike points, this pickup is maintenance free and is capable of accurate trigger signals throughout 10,000 rpm.
MSD techs can point you in the right direction. It takes testing and tuning time to find the best curve that fits your application. Many variables affect the ignition timing curve such as compression, cam specs, intake system, fuel, exhaust, altitude, driving habits, and so on.
MSD’s mechanical advance mechanism is accurate and easy to adjust, so you can try different combinations with the supplied springs and stop bushings. MSD also offers a variety of electronic timing controls, so engines with locked out timing or crank triggers can take advantage of altering the timing as rpm changes.
Note: When you are testing different curves, listen for detonation (spark knock) which is a sign of over-advanced timing.
MSD's tach adapters are solutions to two problems that may occur in a few applications after installing an MSD ignition. They will modify the tach signal of the MSD, so tachs that have trouble picking up the MSD’s signal on select import vehicles with fuel injection systems, will boost the signal, so the ECU can trigger the EFI.
Some tachometers, original equipment and aftermarket, may have trouble reading the MSD’s tach signal causing erratic readings or just not working. An MSD tach adapter modifies the tach signal, so these tachometers can read them correctly. MSD lists different tachs and applications that may require an adapter in an MSD catalog and the ignition control instructions.
Some import vehicles may experience a no-run situation after installing an MSD. This is because some systems use the same trigger source to operate the ignition and the fuel injection. When the MSD is installed, this voltage signal becomes too low to accurately trigger the fuel injection. The PN 8910 tach adapter will usually remedy this problem. Ford Probes and Toyotas require a special adapter that can be ordered directly from MSD.
If you experience any of these problems after installing your MSD, contact our Customer Support Department for more information on your application.
All of the above can be caused by Electro Magnetic Interference (EMI) generated by the ignition system. Specifically through the coil and spark plug wires. The ignition system is a miniature power station and the spark plug wires are its transmission lines. The wires (in particular, “solid core” wires) can broadcast EMI that seeps into electronics and causes erratic behavior.
To combat EMI you need to run a set of helically wound spark plug wires such as MSD’s Heli-Core or 8.5mm super conductor wires. Having the conductor wound around a special center core produces a “choke” that holds EMI inside the wire. On the other hand, solid core wires have no suppression capabilities and should not be used with an MSD ignition. MSD’s super conductor wires have extremely low resistance (less than 50 ohms per foot), yet are designed to suppress EMI like a high-resistance wire.
Other steps to avoid EMI problems include routing your coil’s primary wires away from other plug wires. The magnetic pickup harness coming from the distributor or crank trigger should be routed away from other wires and is a good idea to have it mounted along a metal surface that will act as a ground plain. MSD also offers a six feet long shielded mag pickup cable, PN 8862, that can be used if you are having problems with EMI interfering with other electronics on your vehicle.
Checking for spark output of your MSD is easy. Follow a simple procedure for testing your MSD for spark.