Whether you’re driving a classic car or a high-output, modern muscle car, ignition system upgrades have remained popular with enthusiasts for decades. Engine technology has changed tremendously over the course of the Chevrolet V8 engine evolution, and so have ignition systems. Remarkably, the one thing that seems to be common throughout these platform changes is the HEI distributor. In the ’70s, enthusiasts couldn’t wait to swap their breaker points distributors for the Chevrolet’s new high-energy ignitions with the coil integrated into the cap.

The HEI system produces a more powerful spark, which allows for a wider spark plug gap. This delivers better ignition of the fuel/air mixture. The HEI setup was so popular, it became a must-do swap into non-GM vehicles as well. Performance Distributors is one of the companies that lead the way with its better-than-OE line of distributors. We wanted to know more about the differences between Performance Distributor’s line of high-performance ignition products and the OE-type of ignition components.

Full Clarity

First, let’s start with a full disclosure statement. Performance Distributors is an advertiser to this magazine. However, we have always been objective and shown the performance benefits of increased horsepower empirically – going back as far as 2007 – with Performance Distributors upgrades. This was long before advertising in any of our titles. We built credibility in the industry by surrounding ourselves with proven manufacturers like Performance Distributors. These are professional relationships we maintain to this day. Social media being what it is, we felt it necessary to disclose this before we took the deep dive into the subject.

Ignition coils and distributors are a couple of those components that you can see, but what you can’t see, is what is happening inside the cases or the modules. However, you can measure the difference with dynamometers. In recent years, the trend in ignition systems is an individualized approach to tuning the ignition curve. This gives tuners the ability to offer something larger manufacturers can’t – an ignition system dialed-in to a specific application. Larger companies that make distributors and ignition boxes simply can’t achieve the same level of personal care with their mass-manufactured components.

Performance Distributors fill the gap between mass manufacturing and smaller tuners who dial in components for a specific application. As President of Performance Distributors, Steve Davis explains, “We produce enough components to be a large distributor, but still have the ability to put the extra level of care into our products that larger companies cannot.”

We asked Steve to help explain some of the differences between actual high-performance ignition components and OE-type ignition parts. Some of the topics he discussed may be important points that a casual enthusiast might not have previously considered.

Voltage

Racers and high-performance enthusiasts seem to have the “if some is good, then more is better,” mentality. Voltage is one of the tools used to help sell ignition products, and the higher the number the better the product appears to the public. However, more voltage does not always mean better in the world of ignition coils. Steve says, “The key is to maintain coil voltage under load – the acceleration phase – with little or no drop-off.” This is where he says it’s important to understand that a coil needs to perform consistently from idle through the shift point or redline.

The original GM HEI coils were an excellent example of this. Steve says that the OEM coils were notorious for voltage drop off above or about 5,000 rpm. That might be ok for a half-ton pickup that never sees more than 4,500 rpm, but on a muscle car, especially one that’s been modified, losing voltage means lost engine performance, and not being able to take advantage of the engine’s potential, be it modified or stock. Developing a better HEI coil was actually where Performance Distributors got its start in the ignition business many years ago.

Davis says the key to maintaining consistent voltage throughout the RPM range is in the internal construction of the coil. “We build our coils to use heavy gauge windings and include more windings per coil than found in OEM parts,” Davis says. Doing this allows the coil to more efficiently transfer energy throughout the operating range of the engine.

Built And Tuned By Hand 

The difference between hand-built and custom-tuned is not as broad as you might think. In fact, hand-built and mass-produced have a bigger gap between the two styles. The difference in the performance curve between hand-built and mass-produced is quickly summed up by Davis. “Other distributor manufacturers throw some springs in the box, and it is up to the customer to do some trial-and-error and hope for the best,” he said.

According to Steve, “We stock a supply of distributors with the most common curves on the shelf, but we still custom tune a lot of them.” The guys are able to do this with Sun Distributor machines. These machines are rarely used by many manufacturers. Because these machines are rare, Steve and his crew actually have several for backup. “We have two working at all times and there are several in the warehouse for spares,” said Steve.

Polishing Goes Beyond Looking Good 

Performance Distributors custom makes distributor housings and main shafts on a CNC machine. The CNC machines do great precision work, but not to Performance Distributors standards. So each housing is hand-checked and machined by hand to an even tighter tolerance. According to Davis, “We build the housing to the exact dimensions. This is critical and why we put each piece on a lathe.” Stability and correct dimensions help ensure the distributor will have a long and healthy life.

The housing and mating surfaces are polished so the unit looks nice. “Polishing the housing has no performance benefit at all,” says Davis, adding: “We do that so when the customer pulls it out of the box it looks good. We want them to see and feel the craftsmanship we put into the distributor. The unit is as good on the outside as it is on the inside.”

The Performance Distributors crew polishes the main shaft, paying close attention to the ramps the counterweights ride on by polishing them to an ultra-smooth surface. “This allows for precise movement of the weights, which keeps the ignition timing nice and smooth,” Davis explains. “We try to remove the drag or slowdown of the weight movement caused by a rough surface.”

Clearly, it is not enough to look good. When it comes to performance, it has to react with precision as well. Mechanically speaking, the OE-type distributors do not offer this same level of finish work.

Getting To The Heart Of The Matter 

The perfectly prepared main shaft is dropped down the housing and the magnetic pickup coil is installed. Selecting the best materials is the key to completing the assembly. When Steve says their distributors are hand-built, it goes much further than buying a load of aftermarket parts and assembling them. “We stamp our own weights, and the cams the weights are attached to,” he explains. “We have several different designs, and they are built specifically to our specs. We don’t buy the curve kits that are on the market.” The team focuses on quality control and having our own weights and cams are critical to building a true high-performance piece.

After the weights and springs are attached, the assembly crew attaches a distributor gear with a roll pin. The standard rules apply in gear material. If the engine is equipped with a roller cam, a brass gear is recommended. In most cases, a stock iron gear will work just fine. Performance Distributors also offer a polymer gear that is compatible with any cam. You just need to request one when you order the distributor.

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Each part has a critical area to focus on. According to Davis, “what is critical in the gear installation, is the end-play between the edge of the gear and the housing.” A feeler gauge is used to make sure the proper end-play is achieved. “We check every distributor before it leaves our facility,” he added. End-play that is too tight can bind up and tear up the distributor and camshaft. “In addition, we don’t want the teeth of the gear to get too far out of alignment with the teeth on the magnetic pickup coil. That is where the signal is triggered to the ignition module.”

The weights, ramps, and springs are marked with red stripes on one side. This is to assist customers who take the unit apart for any reason. “We put the red stripes on so customers can reinstall the components correctly. The red stripe faces up.” Davis added, “There could be slight differences if they put it together backward. We want them installed the same way so it has the same timing as it did when it left here. That’s something my dad started years ago.”

The Brain  

Moving on to the ignition module, it is added and a serial number is etched on the base of the housing. That serial number is also recorded to a build sheet the company keeps on file — forever. “If someone changes a cam, they can call back and we can pull the sheet and see if anything needs to be done to the distributor,” explains Davis. Try calling Detroit and asking one of the car manufacturers what changes they need to make when you upgrade to a new camshaft.

The ignition module is essentially the brain of the unit. “This takes the place of dwell points in an HEI distributor,” states Davis. “The module has dwell built into it. We set a few more degrees of dwell throughout the RPM range. But, only enough to make performance improvements. We try to give the coil enough time to saturate and intensify the spark a little more, but not enough dwell time that it goes crazy and burns out the coil.” Having experience and expertise is essential for this type of tuning.

Finally, the rotor and cap are added and the entire unit is then test fired. “We test fire every distributor before it leaves here,” Davis states confidently. “We know they are going to work before they pass through the door.”

Here Comes The Sun

Remember the Sun distributor machine we mentioned earlier? This machine plays a critical role in the quality control process. Each distributor is spun on the Sun machine and checked for critical timing points. “After we dial the number of cylinders into the machine, we check the degrees of spark-advance to ensure the timing is correct for the application,” Steve affirms. “This also makes sure everything is in great working condition. Most of the time, we are looking for 10 to 12 degrees of advance.”

The ignition timing will change depending on the camshaft being used, the compression of the engine, and the application. “It’s going to make a big difference between drag racing or towing. Anything in the 13 to 14:1 compression range, we may put a few degrees less mechanical advance in it when compared to an engine with a 10:1 compression ratio. This is strictly to avoid detonation problems.”

The big auto manufacturers cannot afford to put this level of detail or support into every component they make. With Performance Distributors, ignition is their only business and they take it seriously. Providing the best bang for your buck is what they are all about.

About Performance Distributors

Based in Memphis, Tennessee, Performance Distributors has been producing its proprietary line of HEI-style distributors for more than 44 years. “We are still a family-owned and operated business and we take pride in our products bearing our family name,” says Steve.

Steve’s father, Kelly Davis, is attributed with designing the aftermarket industry’s first HEI performance distributor. Applying his background in drag racing and hot rodding, Kelly experimented with setting advance curves in HEI distributors, mastering the science. He passed these techniques down to Steve, who continues the mastery of advanced ignition-curve technology.

It would appear there is something for everyone within the walls of Davis’ Performance Distributors. The product line ranges from distributors, distributor caps and rotors, to spark plug wires, ignition coils, one-wire Ford alternators, and Dyna-Batt batteries. If it has anything at all to do with getting a spark to the engine, you can probably find it here.

If you can’t find what you are looking for, Davis says all you need to do is ask. “We have many options. If you want a distributor with a timing knob built-in or a slip collar on the main shaft, we can do that,” he said. “If a customer wants the mechanical advance locked out, we have a plate we can install to do that. Whatever they want, we can do.”

To discover all of Performance Distributors’ ignition products, visit them online at performancedistributors.com.