Ford FE engines have several viable performance options for ignition. They are good ones that are equal to those available for any other engines. All FE-equipped vehicles (with rare exception) had a traditional points-style distributor and ignition system from 1958 until 1974. That rare exception was a short-lived transistorized system for race 427 engines. You won’t find those outside of the collector’s environment. In 1975 Ford went to electronic ignition using a magnetic trigger distributor and the Duraspark system.
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Factory Points Distributors
The vast majority of Ford FE engines came from the factory with a single-point distributor. Although there were a variety of advance curve calibrations from the factory, these do not have much relevance to the high-performance builder. The same can be said for the various casting numbers, date codes, and designs.
The high-performance factory engines were available with a dualpoint distributor and no vacuum advance, but these are rare items. And while they run well when freshened up, they are best suited for restoration work. In reality, breakerpoint ignition cannot match the consistency and performance of the CDI ignition system. Therefore a current MSD, Mallory, or similar ignition system is recommended for a high-performance build.
Ford FE distributors actually mount into the engine block and simply go “through” the intake manifold. The block has a small recess just above the cam for indexing distributor housing. The opening in the intake manifold is sealed from oil spray with a cone-shaped rubber O-ring installed on the distributor body. The distributor hold down, while mounted to the intake, actually clamps the distributor housing against the recess in the block, but not the intake itself.
At the bottom of the block’s distributor opening, below the cam gear, is a smaller-diameter guide hole for the end of the distributor shaft, which helps take up any side loads from driving the oil pump. This opening is larger on medium-duty “FT” truck blocks, which necessitates he use of an adapter bushing to run a passenger-car distributor. The bushing was available from Ford, but it has since been discontinued. Therefore, a bushing would have to be fabricated if required.
All Ford factory distributors for the FE used the traditional smalldiameter distributor cap and pushin- style plug wires. A larger-diameter cap with more modern plug-on wiring can be readily adapted using parts from later model small-block engines. Unfortunately, the largediameter cap does not clear some carb and air cleaner combinations, notably the popular 2×4 setups. Those barely have enough room for the standard-diameter cap to fit.
The mechanical-advance mechanism in original Ford FE distributors lies beneath the lower points/pickup mounting plate. A vertical tab that contacts a slot/relief limits total mechanical advance. A pair of springs, which work against pivoting weights, control the rate of advance. To change the mechanical— advance curve rate and amount, you must alter the springs and weights, and also modify the slots or tabs.
Ford vacuum-advance systems work by pulling the points upper mounting plate around a pivot on the fixed-position lower plate. Earlier vacuum-advance canisters have a boltin steel line rather than a hose connection. Depending on the year and vehicle, the later hose-connection canisters may have had either a single or a dual diaphragm. The dualdiaphragm units were emission oriented, and the two connections are rarely used in performance applications, so you plug the retard side. There were varied amounts of advance designed into the originalequipment canisters; some were adjustable using a hex key inserted into the vacuum hose opening. But 40 years of parts swapping, junkyards, parts store rebuilds, and general service have rendered that application data invalid unless you have a known original and untouched part.
Factory-Style Electronic Ignition
Rebuilding an original-points distributor with new bushings and such delivers a reliable ignition for a stock or near-stock-type build. But ignition system technology has long since evolved beyond that level, and electronic ignition systems far surpass the old points systems—so it’s a shame not to use the technology, unless you’re doing a pure-stock rebuild. The advantages of electronic ignition are numerous, including better starting, enhanced reliability, and more consistent high-RPM performance.
The Ford truck distributors from 1975 and 1976 have the same electronic pickup coil and harness connection as other Ford engines of the period. These can be retrofitted to earlier engines and either used with factory-style ignition systems, or to trigger an MSD capacitive-ignition box. These are still available as rebuilt units from most local auto parts suppliers and it’s the most costeffective, solid-performing electronic ignition for your FE engine that uses original Ford parts.
There are a couple of ways to go electronic without looking “new,” which is important on a cosmetically period-correct hot rod. The easiest is to simply run the Duraspark distributor as noted earlier. Although obviously not original, it still looks like a Ford part, because it is one.
The next option is a Pertronix conversion kit. In the 1970s there were a number of similar kits on the market that let you turn a points distributor into an electronic distributor. Pertronix is the only large company that still services that market niche, and it has continued to refine the system over the years. The kit simply replaces the points, and does a nice job in street-oriented builds. You need to remember to retain the ground strap connecting the upper and lower points mounting plates; it is the only way that the Pertronix system gets a usable ground.
Another option is to combine the Duraspark internals with the original Ford points-type distributor housing. I have done some stealthy conversion work to retain the original external appearance while using modern electronic internals on dualpoint or older original-equipmenttype combinations. But there is one thing to keep in mind: If you’re using an OE points-type distributor as a base to work from, modification of a rare or valuable OEM distributor will render it worthless to a collector. It’s a good idea to check out that part number before you start.
FE engine owners always had a variety of distributors to choose from in the performance aftermarket. Mallory, Accel, MSD, and a few smaller companies offered single-point, dual-point, electronic, and even magneto ignitions. While the pointstype systems have faded away, MSD and Mallory still offer high-quality billet parts that are more than up to the task for any build.
Importers have filled the low-cost void with inexpensive distributors that mirror the appearance of highend billet parts at a fraction of the cost. I have no experience with any of these and do not recommend using them. Like most automotive equipment, you get what you pay for and trying to cut corners with an ignition system can be very harmful to an engine.
While an old school aftermarket dual-point or mag might be the visual “ticket” for a vintage race-car look, you need to consider that service items, such as caps, rotors, and internal parts are going to be very hard to find. Cool has its price.
For milder applications, MSD sells a “ready-to-run” distributor with the ignition control module built in. All you need to do is connect the harness as instructed, which requires a ground and 12-volt “key on” signal. The unit includes an adjustable vacuum advance and is as simple as it gets for a street-rod ignition package.
Mallory sells a large-cap Unilite distributor with an optical trigger, rather than the more common magnetic trigger used by Ford and MSD. Although the Unilite is certainly a step up compared to an older factory points system, this package is less popular than the MSD, and hence has fewer options in terms of compatibility with other parts. While I have limited experience with them, others report good results, and it is likely to be a reliable alternative. One note: The large cap may preclude its use with the tight carb clearance of the dual-quad intakes.
For serious street and race engines, the first choice has become the MSD billet distributor. It’s readily available, durable, and very easy to adjust and tune. The MSD billet uses a small-diameter GM-type cap, but it’s a tight fit and just barely clears the front carb bowl on 2×4 setups. A Ford style electronic pickup coil is internally mounted to a non-moving plate. Only two wires extend from the distributor: a purple and green one for the magnetic pickup. An important thing to remember is that the purple MSD pickup wire does not connect to the purple wire in an original Ford distributor wiring harness. MSD clearly states this in the instructions, and some owners still connect the two purple wires. Getting it wrong will have a dramatic affect on ignition timing. The MSD pickup leads terminate into a small plastic “AMP”-style pin connector. I’ve seen folks use a small wire tie to ensure that the distributor and vehicle harness remain connected. I prefer to change the distributor to a self-locking and moisture-resistant WeatherPack-style connector.
The advance weights and springs in an MSD billet distributor are located just below the rotor, similar to the GM configuration. The total advance as well as the rate can be changed in a matter of minutes with the distributor still mounted in the engine. Locking the advance out completely is done off the car, by removing the distributor shaft and rotating it 180 degrees. Once reassembled, the advance is rendered non-functional.
Although the billet unit has no vacuum advance, I won’t miss the feature on race or extreme highperformance engines. With the MSD billet unit, as compared to the readyto- run unit, you have the advantage of choosing the type of ignition control box, and I usually opt for a higher-powered MSD 6 or 7 series. These are capacitive discharge ignition boxes that dramatically step up the coil primary voltage—hundreds of volts compared to the old points systems’ less than 12 volts that. The combination of a coil designed around this ability, better wires, more energy, and electronic ignition’s greater accuracy delivers a faster and stronger spark than was ever possible in the good old days.
Alternately, you can use only the distributor features and bypass the pickup coil entirely to use a crank trigger. The crank trigger is the most accurate means of controlling the spark timing signal. MSD discontinued the FE crank trigger kit a couple years ago, but one can be easily fabricated. The trigger wheel for a small-block Chevy has the right diameter and can be mounted to the damper with only minor bolt-hole tweaking. A fabricated magnetic pickup mount can be attached to the two lower holes in the passenger side of the timing cover. The trigger signal can either be used directly by an ignition box to fire the coil, or it can be modified through use of a timing-control computer.
Plug Wires and Plugs
The demands put on spark-plug wiring for an FE is no different than those of any other engine. As spark energy has increased, so have the requirements for a really good plug wire. Most aftermarket suppliers have kept pace with this need by offering lower-resistance, helically wound wire with large sturdy boots and thick layers of insulation.
I often use the 8.5-mm MSD wiring on race builds. Other manufacturers, such as Taylor or Moroso, offer comparable high-quality wiring products as well. Available in numerous colors, these wires are a good investment for any high-powered engine. But there are places where they just won’t work out. A builder seeking an original appearance uses factory Ford-style valve covers, and the large-diameter wires do not fit through the plastic wire looms. Currently, I am using an MSD StreetFire universal plug-wire set on such projects. It is just small enough in diameter to fit the wire holders (barely) and the black color is unobtrusive.
Remember, when routing wires, you need to keep the plug wires for cylinders number-7 and -8 away from each other to prevent a crossfire, which can really happen. Use dielectric grease on the boots to prevent seizing and voltage leakage to ground. Also, keep plug and coil wiring away from any electronic signal leads, such as the ignition trigger harness or EFI wiring. Inductive fields can play havoc and sometimes be nearly impossible to diagnose.
The factory FE cylinder heads accept the older-style 18-mm spark plugs with a 13/16-inch hex. The old Autolite/Motorcraft numbers were BF42—BF32 on the high-performance engines. Most new heads, including Edelbrock and Blue Thunder, use the more common 14-mm, 3/8-inchreach plugs with a 5/8-inch hex. These smaller plugs are set deeper into the chamber, and reaching them can be a challenge because they’re set into a machined “well” in the exhaust side of the head. Cutting down the outside diameter of a 5/8- inch plug socket on a lathe helps out considerably. I normally start my dyno tuning with a Champion Racing C61YC plug, but that is from my familiarity with reading them. Other similar plugs from other manufacturers certainly work as well. The Autolite 3924 seems to be a good selection for street-oriented builds.
The MSD billet distributor has a .531-inch-diameter shaft. If you need to change to a bronze distributor gear for a solid-roller cam, the gear from a 429/460 Ford works perfectly. Factory Ford distributors use a .437- inch shaft diameter, while the Mallory Unilite has a .500-inch shaft. All sizes are readily available.
The Ford and MSD distributors use a .125-inch-diameter spiralwound pin for gear retention. In addition, they rely on a fairly snug press fit. If you are having problems with pins shearing or are trying to save a distributor with pin-hole damage, it is possible to drill out the pin hole diameter and use the larger-diameter roll pin from a small-block Chevy.
The FE tunes just like any other engine. Total advance depends on the compression, cam, available fuel quality, and combustion chamber and piston design.
In broad terms, an original equipment iron-head engine wants between 38 and 40 degrees of total timing. An Edelbrock-headed package is best somewhere between 34 and 38 degrees total. A Blue Thunder head engine, with a more efficient chamber, wants between 28 and 36 degrees. But there is a huge amount of variability within those ranges, and every combination is different. The only way to tell what your engine really needs is to try it. As a caution, though, if you are really far away from those numbers, it’s likely that something is wrong. A spun damper or a bad timing light can really throw you off course. And remember to correctly connect the MSD pickup coil wiring. I’ve seen that get reversed when going from the dyno to the car.
Idle-timing needs are dependent on idle-speed desires, transmission type, converter selection, and (of course) the chosen cam. You have two options if you find yourself with a car that idles perfectly and runs great but has too much base timing for the starter to spin it over. You can run very light springs in the distributor, which let you crank with less lead but bring in the timing as soon as the motor fires up. Or you can run an ignition bypass to spin it over without spark and then light it up once turning—cool in a race car but a bit awkward on the street.
Written by Barry Robotnik and Republished with Permission of CarTech Inc
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