Racers are famous for being able to break just about anything. And not surprisingly, we're no different from them. A perfect case in point is our dyno test mule engine. We recently used it to test different rocker arm setups and destroyed two of the six rocker sets we tested. What we didn't mention in that story ("Design Matters," Mar. '07), however, is that we also managed to hurt our Mallory HEI ignition.
It wasn't deliberate. The Mallory distributor had served its duty well on previous dyno tests, but this time we had a wiring mishap while hooking the engine up to the dyno. Somehow, a ground wire was hooked to the lead for the tach, and before long a faint wisp of smoke from underneath the rotor cap indicated that something was amiss. Names will not be revealed here because it was an honest mistake that anyone could make (although we are reserving the right to blackmail the guilty party later). Thankfully, a race-bred ignition like our Mallory is easily rebuilt.
We blew the coil (left) by...
We blew the coil (left) by hooking a ground wire to the tach lead (even though it's plainly marked).
Since an HEI uses an internal coil, it is easy to wire and a foul-up such as ours is quite rare. However, regular wear-and-tear from racing is an issue. Being the inventive lot we are, there are a number of additional ways racers can damage equipment. In the interest of getting our ignition up and running again, we gave the folks at Mallory a call to inquire about rebuilding it. They sent us the components to complete the task ourselves, which was surprisingly easy. Our replacement components included a new performance coil (PN 29215), which is effective up to 7,000 rpm, a rotor (PN 362), and a Hyfire HEI module (PN 699). So, if you burn a coil, chip the rotor, or create any other damage, consider rebuilding your own HEI distributor. Mallory's high-power module and coil are also compatible with stock distributors as power upgrades. If your class requires stock components, this is a good way to get rid of a high-speed miss (the curse of stock HEI ignitions) while keeping that stock look.
Even though the rotor shows...
Even though the rotor shows only minor wear at the tip, we decided to replace it. The two slotted bolts had to be removed first.
Easy Fixes
Having an ignition problem? The following is a list of the most common technical questions asked of Mallory's Mike Golding along with practical solutions for each.
Q I put a new high-output ignition system in my car and it started missing. I thought something was wrong with the ignition, so I exchanged it for another one. It is still doing the same thing. What's going on?
A The problem isn't the ignition box. It is somewhere else, and that somewhere is often the spark plug wires. Here's what is happening. Your new high-output ignition delivers several times more current to the spark plugs, and the wires probably cannot contain it. So they leak energy or short out to ground. Resistor plugs can contribute to the problem as well as corroded terminals or ill-fitting boots on the wires.
The rotor cap still looked...
The rotor cap still looked good, so we kept it. We elected to remove the carbon brush, rubber washer, and ground strap since replacements for all those components are included with the new coil.
It's like the hose you use to wash your car. When the nozzle is open and there is very little pressure in the hose, the nozzle only leaks a little at the connection between the hose and the nozzle. When you close the nozzle and the hose builds up pressure, water sprays from that bad connection and soaks you.
Q I just put a new cap on my distributor and the car started to miss. I took off the cap and the carbon tip inside the cap was chipped. Was it a bad cap?
A The cap was probably just fine. What went wrong was the installation. It is very important to lower the cap straight down onto the distributor. Otherwise, the tip of the rotor catches the edge of the carbon and it chips.
Q Why do the catalogs always tell you what coil to run with a particular ignition, especially with a CD ignition? Are they just trying to sell more parts?
The module is held in place...
The module is held in place with three screws. The three plugs are different, so there is no need to mark anything.
A Especially in the case of a CD ignition box, the coil is an integral part of the ignition system. The box and coil are designed to work as a team. If things are not compatible, you not only lose performance, you also generate excess heat either in the coil or in the ignition box.
Q Is the manner in which I mount my new coil important?
A Yes, for a couple of reasons. First of all, some coils are filled with special oil that keeps them cool inside. They are designed to have a little air space at the top, away from the heat-generating windings. Mounting them the wrong way can cause them to overheat internally.
Here's a helpful hint. Try to mount your coil in such a manner that the coil wire will only need to be 18 inches or less. Also, try to keep it away from as much heat as possible and where there is some airflow.
Q I just installed a new ignition box and something doesn't feel quite right. I wired in my new one the same way I wired the other brand I had. What gives?
A Whenever you add a new ignition box, you need to recheck the ignition timing. It often changes a couple of degrees, even if you are just going from one box to another.
Q I noticed some HEI distributors have two wires to hook up and others have three. Why the difference?
A Some distributors use a separate ground wire while others count on grounding through the housing. A separate ground wire is cheap insurance and highly recommended. Most distributors have a gasket between the housing and the engine, and the housing has O-rings. That leaves only the distributor/oil pump drive, which is coated in oil, and the distributor clamp to supply the ground.
 With the distributor torn...  With the distributor torn down this far, it's a good idea to check the shaft for excessive play. |  Before attaching the new module,...  Before attaching the new module, wipe a thin film of the supplied heat sink grease across the entire surface of the module's aluminum heat sink. |  After attaching the module...  After attaching the module to the distributor housing (do not apply too much torque), connect the two wires from the pickup/stator assembly to the two terminals. |
 This set of switches tells...  This set of switches tells the module how many cylinders the engine has and sets the rpm limiter. |  The rotor is keyed so that...  The rotor is keyed so that it will only go on one way. There are no worries about installing it backward. |  The new ground strap and carbon...  The new ground strap and carbon brush (center) drop right into place. |
 A thick rubber washer provides...  A thick rubber washer provides an insulator between the coil and the brush and simply drops into place. |  Position the coil loosely...  Position the coil loosely over the cap and insert the terminals for the red (battery) and yellow (coil) wires into the cavity on the distributor cap. |  The coil is secured to the...  The coil is secured to the cap with four self-tapping screws. |
 Before reinstalling the distributor...  Before reinstalling the distributor into the engine-especially if you are using a new cam or distributor gear-give the distributor gear a good coating with some type of lubricant. |  It is possible to rebuild...  It is possible to rebuild your HEI ignition while the distributor housing is still in the engine. If this is the case, you still need to recheck the timing when firing up the engine. Even if the housing hasn't moved, changing the components can result in a timing change. | |