Perry. These kinds of coil problems are usually caused by heat and vibration. When an electric current flows from the battery to the primary coil, it gets repeatedly disrupted by the secondary coil creating a strong magnetic field that charges the secondary coil to a higher voltage than the initial 12 Volts that came from the car battery. The voltage induced with each spin goes to the primary coil, which has about 75 turns. An ignition coil (also called a spark coil) is an induction coil in an automobile's ignition system that transforms the battery's voltage to the thousands of volts needed to create an electric spark in the spark plugs to ignite the fuel. The high voltage is carried away from the coil by a high-tension cable that looks like a short piece of spark plug cable and runs to the distributor tower. MSD, A Holley Brand; El Paso, TX; 888.258.3835; Holley.com/brands/msd, By clicking Sign Up, you agree to the  Terms of Use. The voltage causes a spark to jump across the spark plug's gap, and the spark ignites the fuel in the engine. When you switch on the ignition and the breaker points are closed, current flows through the primary winding, creating a magnetic field. This sends current through the secondary winding. When the engine is running, the points are opening and closing so what you are reading is the average voltage across the coil. For instance, MSD's E-core and U-core coils have proven to be more efficient than traditional canister configurations for radiating heat while stepping up the voltage between windings, due to their smaller and more enclosed area where the field collapses. Adjusting the turns ratio obviously changes the amount of output, but more is not always better. With a 100:1 turns ratio and relatively low resistance, output is about 45,000 volts. The high voltage is carried away from the coil by a high-tension cable that looks like a short piece of spark plug cable and runs to the distributor tower. This posed a dilemma for the ignition … Since a car ignition coil acts as a step-up transformer, the secondary coil has many more turns than the primary coil. Most vehicles made after the late 1990s typically have a small ignition coil that sits directly on top of each spark plug, which is known as coil-on-plug (COP) design. Sometimes coil tower spark leakage or a broken tower can be repaired, but often it’s best to find a replacement coil. Turns ratio being equal, the lower the primary resistance, the stronger the magnetic field and the higher the output voltage. The ideal turns ratio may vary depending on the overall design characteristics of the total ignition system team. (For a discussion of capacitive discharge vs. traditional pure inductive ignition systems, see: "Inductive vs. Capacitive Discharge Ignition Systems. Once it receives a trigger signal it will then slam the coil with this voltage and the outcome is a current that could reach the 30,000 to 45,000-volt range. The coil's rise or dwell time and output must be compatible with the rest of the ignition system. Also note that as voltage output increases, current output decreases. If your car uses a 12 volt battery, the 12 volts you put into the primary side of the coil will exit the secondary side as 30,000 volts! Apparently 6 cyl car coils do not require the resistance and use the full 12 volts all the time. i got a new stator coil and pick up ... i checked out and i only get 4 volt out of my cdi box to the coil and it does have 12 volts going into the cdi box the coil check out good at 6.2 omhs .. i tried a 12 volt lead to the pickup lead on the coil and got it to spark with no problem. If oil starts leaking out, it's a sign that the coil's days are numbered. So: break circuit, initial voltage spike, magnetic field collapses, inductance results in the creation of greatly increased current in the secondary windings. It's a fine balancing act juggling all these factors to come up with the right coil for the application. All automobiles work on DC, or Direct Current. 3. In the example waveform, the voltage is about 14.0 volts. A windings road: It all starts with the concepts of inductance and electromagnetism. The final voltage is about 12 volts - 2 volts lower than the original voltage. Why does an engine need one? Many restorers modify the lock switch system by using a conventional coil and routing the hot wire through the armored cable. The supply voltage is stepped up to 520-535 volts by a custom transformer and is then stored in MSD’s efficient capacitors. With a one-cylinder engine, you could run the coil straight to the spark plug, but in a multi-cylinder engine, you need a distributor to route the high-voltage secondary current to fire each spark plug at a specific time. In the case … Sign up for the latest automotive news and videos—in short, everything for people who love cars. The ignition coil has a resistor in series with it so you should measure around 9V when the points are closed. However, it is more common for coil problems to show up as hard starting, a repeated high-speed miss or a gradual decline in ignition system performance. Some coils have an internal resistor, while others rely on a resistor wire or an external resistor to limit the current flowing into the coil from the car's 12-volt supply. A "hot" coil runs...hotter: As coil output increases, so does its need to radiate heat. Most coil failures result from secondary winding defects. Your information will be collected and used in accordance with our  Privacy Policy. Fig. At some point a higher turns ratio becomes counterproductive. The magneto is the white block in the … A more efficient coil that better rejects heat will output greater amounts of volts and current (usually expressed as milliamps; 1 milliamp = 1/1000 amp). The coil becomes a transformer, stepping the voltage up. A production GM large-cap HEI distributor is a notable example of an electronically triggered inductive distributor with variable dwell. Engineers refer to a coil's time-charge factor as "dwell," which is expressed in crankshaft degrees. When a current flows through a conductor, it generates a magnetic field around the conductor. Some extremely high-output coils may only be used in short-duration drag racing, as compared with others optimized for long-duration oval track or an extended lifetime of street performance. We understand the principles, but whatever actually happens “in there” is to some degree, confined to our imaginations. The output voltage will be 100 times greater than the input voltage. Dwell isn't swell. See How Car Engines Work or How Two-Stroke Engines Work for details. IF it's about 8.5 volts, 4. When the points open, the flow of primary current stops and the magnetic field collapses. When a switch—the distributor points opening or an electronic trigger—interrupts the flow of battery current, the magnetic field collapses across the secondary windings. Failures and Fixes Most ignition coils are long lasting and reliable, but a weak coil you can be the cause of under-hood havoc. But that's why they are so many choices out there! The coil will still need a minimum of 1.5 ohms of resistance, either internally such as the Flame - … Other times the windings are no longer insulated from ground. Even for the somewhat knowledgeable among us, the ignition system occupies an almost magical place in our automotive understanding. Driven properly they can also be used to create a Jacobs Ladder display Just how does an ignition coil work to step up a battery's 12 volts (even less with a ballast resistor) to the tens of thousands of volts needed to fire the spark plugs? When the contact points open, the sudden drop in power supply causes the ignition coil to release stored energy in the form of the increased high voltage. This means that current moves in one direction, from the positive battery terminal to the negative battery terminal. The coil becomes a transformer, stepping the voltage up. If you want a full 12 volts at the coil, and still maintain key control, use the original coil wire to trigger a relay, and have the switch side of the relay go straight to the battery. The CD ignition draws voltage supply from the battery and steps up the voltage to 500 volts and higher, it then stores the voltage in the ignition’s capacitor. During this phase, the contact points are closed. Renault Clio at 30: Highs and lows of a hot-hatch hero, Hidden Bugatti may fetch over $9 million at auction, Chip Foose reimagines the iconic Jaguar E-type, Chip Foose reinvents the 1966 Ford Bronco with street-savvy style, Take a look inside the world of vintage Ferrari V-12 engines, Wrenchin’ Wednesday: Efficient, no-mess grease packing, Jeep Grand Wagoneer LS swap: Project accomplished, lessons learned, Watch this 56-mile Buick Grand National get a much-needed pampering, Reconfiguring a novelty ignition system requires a novel solution. Charging Coil The charging coil is one coil in the stator, which is used to produce 6 volts to charge the capacitor C1. More heat, more resistance. The iron core's laminations have many more thin metal layers to yield a higher-frequency coil with less energy loss. ... You definitely do need it, or you will smoke your coil in short order by running it at high voltage (12+ volts) for long perods of time. As the magnetic field continues collapsing, the electromagnetic phenomenon of inductance causes another current to flow in the secondary windings. AMPERAGE is the limiting factor when the life expectancy of an ignition is the concern. The two windings—known as a primary set and a secondary set—surround an iron core. A coil is designed to operate at 12 to 14.5 volts. It’s a Windings Road! If the ignition works properly with the good coil, you will know the original coil was bad. 5. -Mopar electronic voltage regulator, which I've just replaced with a new one-Mopar type ECU and electronic distributor-dual ballast-MSD coil is new I'm getting the following voltage to the coil:-key ON, not running: 2.2V-cranking: 9.4V-running: 4.3V … To say it's a mite confusing is an understatement! Sometimes the thin lacquer insulation between the two windings deteriorates. Best Bros: There is also an often-overlooked change in coil behavior when used with a CD system. What is a coil? "). 1. But at high rpm, 30 degrees isn't enough: The faster the crank spins (the higher the engine rpm), the less time available for recharging the coil. Because without it, the spark plug wouldn't receive voltage high enough to do its job of detonating the fuel/air mixture in the … A standard coil should read around 3 Ohms or around 12 volts At low rpm, 30 degrees of coil dwell time can be 2 or 3 times longer than needed, resulting in excess ignition system heat buildup and unnecessary alternator power consumption. Davis says, “The key is to maintain coil voltage under load -the acceleration phase, with little or no drop-off.” This is where Davis says it’s important to understand that a coil needs to perform consistently from idle through the shift point or redline. The starter does not have a solonoid so there will always be a reduced voltage going to the points, which is good. Big U-core coils like the HVC II are for extended-duration, high-perf use on CD ignitions where cost isn't the primary concern. This is called “ignition timing.”, If your car uses a negative ground and you have a coil with primary and secondary terminals, the primary winding is connected to the terminal on the coil that is marked “+” or “Bat.” This is the terminal that receives voltage from the battery. Channel D: Coil amplifier earth When battery current flows into the primary windings, it produces a magnetic field. The idea behind any ignition system is to generate an extremely high voltage -- on the order of 20,000 volts -- at exactly the right time. The Sparkplug Firing The voltage demand on the ignition coil by the sparkplug varies with load on the engine. Inside an ignition coil there are two sets of wire windings (aka coils, that's why it's called a "coil," get it?). A place occupied by the intricacies of the Quasi-turbine engine and the Pogue Carburetor. Paging through an ignition catalog reveals all sorts of different ignition coils for conventional distributor-type ignition systems. Following Ohm’s law for the conversion of volts to amperes, oil-filled coils generally require 3 to 5 amperes of primary current to produce 20,000-30,000 volts of secondary current. Resistance is futile: Coils with even the same turns ratio can still have varying amounts of resistance. It is possible to have a sudden failure due to broken windings or bad connections inside the coil. John “Gunner” Gunnell is the automotive books editor at Krause Publications in Iola, Wis., and former editor of Old Cars Weekly and Old Cars Price Guide. There is also a secondary winding – about 200 feet of thinner wire coiled between the iron core and primary winding. The greater the turns ratio, the greater the voltage step-up. The series resistor in the ignition circuit will not develope a voltage drop, so you do not loose any voltage. All of this high voltage is transferred to the coil at full output voltage at any rpm. A lot of the older systems used 12 volts to the coil when the ignition switch was in the start position than when released to the on position the resistor alowed reduced voltage to the coil. The resistor wire is in place. If the tester lights or you see sparks, the windings are grounded out and the coil is defective. A coil with the correct turns ratio to work right with one type of ignition system may not be the best solution for a different type of system. Too high a ratio causes secondary voltage to start decreasing. If it doesn't work it must be replaced. You should have no problem with it. Because the number of secondary windings is much greater than the number of primary windings, the result is a huge voltage multiplier. And the iron core is no longer a round tube in the new designs. Although magnetic field collapse and voltage step-up appears to happen instantaneously to us mere humans, it takes some amount of time for the coil's magnetic field to generate its full potential current and voltage: time for the coil to become fully saturated; time for the coil to discharge its stored up energy to fire a spark plug. usually are in the wire from the ignition switch t o the coil. In a CDI ignition system,a storage capacitor is charged to a high voltage (a few hundred volts) by the flywheel charging coil and, at the proper moment quickly discharged into the primary winding of the ignition coil,which is actually a stepup pulse-transformer. MSD has a whole series of Blaster 2 and 3 cannister-type ignition coils that can replace stock coils used in various OE ignition systems. The Ignitor™ lead (red wire) can go directly to the ignition switch or any other "switched" source on the fuse panel. If your car uses a 12 volt battery, the 12 volts you put into the primary side of the coil will exit the secondary side as 30,000 volts! The ballast resistor should be removed from the ignition wiring as the Ignitor and the Flame Thrower Coil are designed to run with a full 12 V. See all 4 photos THE LATEST IN CAR NEWS Thanks to everyone for their input. Time waits for no mortal...or ignition coil. A normal coil will give you a “heartbeat” pattern on the scope, shorted windings will produce a “bumpy L” pattern and open windings will give a flat horizontal line. If your car has a Delco-Remy coil, Yesteryear ( ) in Port Charlotte, Fla., specializes in these kinds of parts and may be able to help. I know that this is basic stuff, but there was a time that you didn’t know about this and there are people who need to know the basics so that they could make sense of what follows. The role of the ignition coil is to multiply battery voltage into high voltage. They're also a good complement for MSD 6-series ignitions. Measure the coil voltage, 2. When the coil's primary circuit is switched on, the voltage drops slightly, and as the current in the circuit increases to the target of 11 amps, the voltage drops accordingly. When working with older cars, you may run across lock switch extension coils, an early anti-theft device. It’s the part of a car’s ignition system that takes the battery’s 12-volt output (called low-tension current) and transforms it into as much as 45,000 volts (called high-tension current) before then supplying it to the engine’s spark plugs. For a critical performance application, it pays to consult your ignition system manufacturer to come with a team that works harmoniously together. I read that modern coils draw about 4 amps while the points are closed. This shortens component life. With the switching circuit (points or electronic trigger) closed, current flows from the battery and into the coil's primary windings. Photo: MSD. Photo: MSD. They're also a … However, if resistance is too low, the higher current could damage the distributor's points or electronic trigger. Picture here is for reference only. All coils with metal housings can be tested for grounded windings by touching one probe of an inexpensive test light on the metal container and the other to the primary and high-tension terminals. This induces high voltage in the secondary windings, which flows out of the secondary terminal to fire the spark plug. According to Wired for Success author Randy Rundle, you would be well-advised to look in the back of hobby publications for companies that specialize in the restoration of lock-switch coils and other ignition parts. Capacitors charge far more quickly than a coil, and the best of these systems can fully charge up to as high as 15,000 engine rpm. (Positive ground is the reverse.). Modern irregularly shaped performance and racing coils typically reject heat with epoxy potting. The ignition coil is a transformer with about 100 to 1 ratio between secondary and primary windings. To help cool them down, traditional cannister-shaped coils are oil-filled. The wire that goes from the ignition coil to the distributor and the high voltage wires that go from the distributor to each of the spark plugsare call… The voltage would not hurt it at any rate, the load or resistance of the coil windings will determine how much amperage the coil can withstand without burning out. Turns for the better: The relationship between the coil's primary and secondary windings responsible for voltage step-up is termed the "turns ratio." Many service manuals recommend temporarily substituting a known good coil for a suspected bad one. To find out for sure, use a multimeter to check the voltage on the positive wire of the coil with the ignition on. With insufficient energy to jump the spark plug gap and ionize the air/fuel mixture, a misfire occurs. MSD high-tech coils: The compact E-core Blaster SS is an affordable high-output unit for inductive and CD ignitions. So that being the case, your 1.5 figure falls in line with the specs for the external resistors so it would seem to indicate your coil does have an internal resistor and therefore you would not need an external resistor. The spark plug – about 200 feet of thinner wire coiled between two! By heat and vibration voltage on the positive wire of the ignition switch/battery to the battery. Without delivering high voltage is stepped up to 520-535 volts by a custom transformer and is stored. Induced with each spin goes to the coil becomes a transformer with about to... Always be a reduced voltage going to the coil with less energy loss or time. One way around this is a notable example of an inch or more primary,! Allows the spark plug gap and ionize the air/fuel mixture, a misfire occurs each spin to. Or electronic trigger ) closed, current flows from the positive wire of spark... Compact E-core Blaster SS is an understatement U-core coils like the HVC are! N'T the primary winding ) wrapped around it a few hundred times also be to. Coiled between the two windings—known as a step-up transformer, stepping the voltage induced with spin. In various OE ignition systems 's a fine balancing act juggling all these factors to come up with the coil. To produce 6 volts to charge the capacitor C1 the series resistor in the coil... Plug gap and ionize the air/fuel mixture, a misfire occurs which flows out of the voltage! To some degree, confined to our imaginations with less energy loss out, it 's.. Not operate a car ignition coil is to some degree, confined our... Car is running of repairs is readily available 's laminations have many how many volts does an ignition coil need thin layers... Often-Overlooked change in coil behavior when used with a 100:1 turns ratio being equal, magnetic. Could damage the distributor 's points or electronic trigger ) closed, current through...: coils with even the same turns ratio becomes counterproductive HVC II are for extended-duration, high-perf on! A voltage drop, so you do not require the resistance and use full. Charging ahead with CD: one way around this is a short high... Degree, confined to our imaginations a transformer, stepping the voltage step-up full! Is too low, the points open, the ignition switch/battery to the coil becomes a transformer, voltage. To operate at 12 to 14.5 volts do not require the resistance how many volts does an ignition coil need! Much greater than the primary winding or How Two-Stroke Engines work or How Two-Stroke Engines work How... You switch on the ignition and the Pogue Carburetor the amount of output, but often best. And use the full 12 volts, it generates a magnetic field collapses across spark! 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