There are several ways to upgrade from a points and condenser system to an electronic system.  If your vehicle's engine was built in the 1960s, chances are that you might be able to find a similar engine from the 1970s that used an electronic system.  This will involve some homework on your part in understanding the wiring under the hood of your car.  You will need to find a suitable donor car which will involve some more homework.  An excellent source of information are on-line discussion forums for your vehicle.  Chances are that someone has already done this upgrade and would be happy to share his experience with you.

Once you have identified the parts you need, you will only need to visit to the local junkyard if you're lucky.  You might need to once again turn to the discussion forum for help in locating the parts you need.  You might also want to upgrade other under hood components like a more modern charging system at this time as well.

An other option is go the aftermarket route and try to find a company that has a kit to make the conversion.  Pertronix Performance Products (http://www.pertronix.com/) is one company that makes kits for a wide variety of vehicles.  More common engines (like the Chevrolet small block) will already have a huge number of products available for it.

Failing that, you may want to consider a modern crank-triggered CDI system.  This involves the installation of a trigger wheel on the crankshaft and a pickup sensor beside it.  Companies that produce engine management systems will likely have a product for you.

http://en.wikipedia.org/wiki/Spark_plug

http://www.findarticles.com/p/articles/mi_qa3828/is_200505/ai_n13640862/pg_1 (spark ignition wave forms)

http://www.edelbrock.com/automotive/sparkplugs.html (includes Edelbrock/Champion cross reference)

http://www.cvproducts.com/cv/technical/sheets/spark/Autolite.pdf

http://www.cvproducts.com/cv/technical/sheets/spark/Champion.pdf

http://www.centuryperformance.com/spark.asp

Spark Plug Heat Range:

A spark plug's heat range has no relationship on the actual voltage transferred through the spark plug. Rather, the heat range is a measure of the spark plug's ability to remove heat from the combustion chamber. The heat range measurement is determined by several factors:

The length of the ceramic center insulator nose
The insulator nose's ability to absorb and transfer combustion heat
The material composition of the insulator
The material composition of the center electrode
The longer the insulator nose gives you a larger surface area exposed to combustion gasses and heat is dissipated slowly. This also means the firing end heats up more quickly. We are talking about exposed ceramic length, not extended tip length.

The insulator nose length is the distance from the firing tip of the insulator to the point where the insulator meets the metal shell. Since the insulator tip is the hottest part of the spark plug, the tip temperature is a primary factor in pre-ignition and fouling. No matter what the plugs are installed in, be it a lawnmower, a boat, your daily driver or your race car, the spark plug tip temperature must remain between 450°C to 850°C. If the tip temperature is lower than 450°C, the insulator area surrounding the center electrode will not be hot enough to deter fouling and carbon deposit build-ups, thus causing misfires. If the tip temperature exceeds 850°C, the spark plug will overheat which can cause the ceramic around the the center electrode to blister as well as the electrodes will begin to melt. This may lead to pre-ignition/detonation and expensive engine damage. (see the plug pictures that are part of this article)

In identical spark plugs, the differences from one heat range to the next is the ability to remove approximately 70°C to 100°C from the combustion chamber. A projected style spark plug firing temperature is increased by 10°C to 20°C.

The firing end appearance also depends on the spark plug tip temperature. There are three basic diagnostic criteria for spark plugs: good, fouled, and overheated. The borderline between the fouling and optimum operating regions (450°C) is called the spark plug self-cleaning temperature. This is the temperature point where the accumulated carbon and combustion deposits are burned off automatically.

Bearing in mind that the insulator nose length is a determining factor in the heat range of a spark plug, the longer the insulator nose, the less heat is absorbed, and the further the heat must travel into the cylinder head water journals. This means that the plug has a higher internal temperature, and is said to be a "Hot" plug. A hot spark plug maintains a higher internal operating temperature to burn off oil and carbon deposits, and has no relationship to spark quality or intensity.

Conversely, a "Cold" spark plug has a shorter insulator nose and absorbs more combustion chamber heat. This heat travels a shorter distance, and allows the plug to operate at a lower internal temperature. A colder heat range can be necessary when an engine is modified for performance, subjected to heavy loads, or it is run at high RPMs for significant periods of time. The higher cylinder pressures developed by high compression, large camshafts, blowers and nitrous oxide, not to mention the RPM ranges we run our engines at while racing, make colder plugs mandatory to eliminate plug overheating and engine damage. The colder type plug removes heat more quickly, and will reduce the chance of pre-ignition/detonation and burn-out of the firing end. (Engine temperatures can affect the spark plug's operating temperature, but not the spark plug's heat range).

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Influences on Spark Plug Temp and Performance:

Below is a list of possible external influences on a spark plug's operating temperatures. The following symptoms or conditions may have an affect on the actual temperature of the spark plug. The spark plug cannot create these conditions, but it must be able to deal with all the levels of heat, otherwise performance will suffer and engine damage can occur:

Air/Fuel Mixtures seriously affect engine performance and spark plug temps.

Rich air/fuel mixtures cause tip temperature to drop, causing fouling and poor drivability.
Lean air/fuel mixtures cause plug tip and cylinder temperatures to increase resulting in pre-ignition, detonation, and possibly serious spark plug and internal engine damage.
It is important to read spark plugs many times during the tuning process to achieve optimum air/fuel mixture. Computer-controlled engine applications do a pretty good job of this with the various sensors that report back to the ECM.
Higher Compression Ratios and Forced Induction will elevate spark plug tip and in-cylinder temperatures.

Compression can be increased by performing any one of the following modifications:
a) reducing combustion chamber volume (i.e.: domed pistons, smaller chamber heads, milling heads, etc.)
b) adding forced induction (Nitrous, Turbocharging, Supercharging)
c) camshaft change
As compression increases, a colder heat range plug is required, as well as higher octane fuel and paying careful attention to ignition timing and air/fuel ratios are also necessary.
Advanced Ignition Timing: Advancing timing by 10° causes plug temperature to increase by approximately 70°C to 100°C.

Engine Speed and Load: Increases in firing-end temperatures and are proportional to engine speed and load. When traveling at a constant high rate of speed, or carrying/pushing very heavy loads, a colder heat range spark plug should be installed.

The heavier your vehicle or greater the amount of work the engine sees (racing applications, construction trucks, vans, RVs & Motorhomes, etc.), the more critical this becomes.

Ambient Air Temperature:

As air temperature falls, air density volume increases, resulting in leaner air/fuel mixtures. This creates higher cylinder pressures and temperatures that causes an an increase in the spark plug's tip temperature. Fuel delivery should be increased.
As temperature increases, air density decreases, as does intake volume, and fuel delivery should be decreased.

Humidity: As humidity increases, air volume decreases. The result is lower combustion pressures and temperatures, causing a decrease in the spark plug's temperature and a reduction in available power. Air/Fuel mixture should be leaner, depending on ambient air temperature.

Barometric Pressure and Altitude:

Affects the spark plug's temperature
The higher the altitude, the lower the cylinder pressure becomes. As the cylinder temperature decreases, so does the tip temperature.
Many tuners attempt to "chase" tuning by changing spark plug heat ranges.
The real answer is to play with the jetting or air/fuel mixtures in an effort to put more air back in the engine.

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Last modified: February 25, 2008