We’ve seen it time and again: Racers who are absolutely genius with a wrench in their hands are left cussing and spitting when an electrical problem crops up on the race car. As mechanical people, we are trained to think when part A moves, part B should react in a specific way. And when part B–whether it is a suspension component, or a throttle linkage, or whatever–doesn’t respond the way we want, we observe what’s going on and fix it.
But electricity doesn’t work that way. You can’t watch it work. And you can’t even hear it–unless you count the maddening sound of an engine misfire. With the exception of the moving parts in your distributor, an ignition system doesn’t behave mechanically, so working with one requires a different way of thinking.
Thankfully, here at OneDirt we’ve got the connections to get the answers you need. Terry Johnson is the brains behind Crane Cams excellent ignition systems, and he agreed to help us answer some of the most common questions he hears from racers. If you don’t see the answer to your particular problem here, he also suggested you give Crane’s tech department a call no matter what brand ignition you are running in your race car. We’ve printed Crane’s contact information at the end of this article.
I’ve heard a crank trigger ignition is supposed to be better than a standard distributor, why?
It is better in that the accuracy is increased compared to conventional distributors. A crank trigger times the ignition off the position of the crankshaft instead of using the camshaft to spin the distributor on a more traditional system. When the distributor is spun by the camshaft you can potentially reduce timing accuracy from several factors, including slack in the timing chain, flex in the camshaft and even wear in the distributor gear. By timing the system at the crank, you cut out all those areas that can be a problem.
What is an optical trigger distributor? How is it different from a standard distributor?
An optical trigger distributor is where we utilize a light emitter and sensor instead of the usual magnetic reluctor wheel because it is much more accurate, especially at high rpm levels normally seen in racing. There is a metal disk or wheel that spins between the light emitter and the sensor. Holes spaced in the disk allow light to hit the sensor, triggering the ignition to send a spark to the appropriate cylinder.
Because we are talking about operating at the speed of light, the ignition timing is incredibly stable all the way through the rpm range. A traditional system with a magnet and reluctor wheel as trouble maintaining accuracy as the rpms go up.
Our optical pickup distributors have near crank trigger accuracy of +/- .01-.05 degrees. And the proof is simple. When you put a timing light on an engine using one of our optical trigger distributors, it looks a lot more like a crank trigger ignition because it is so stable. Like I mentioned, it moves only a half of one degree maximum. But a magnetic trigger signal can jump as much as three or four degrees. When you set your timing you want to be absolutely as accurate as you can, so why would you be willing to allow your distributor to move that setting around by four degrees when you are on the race track?
I use a pressure washer to clean my car but am always worried about using it near the engine. Any tips on cleaning my car without ruining the electronics?
It is never advisable to directly spray any of the ignition components with water, regardless of the manufacturer. If you can, remove those components or put plastic bags over them and seal the bags as best you can. However, I will say that Crane’s ignition components are all very resilient to water. Our product line is completely sealed in soft urethane to help protect the interior components from any liquid contamination.
Is it better to lock out the advance or leave it functional?
That totally depends on the application. I can’t give a blanket statement here, because it really depends on many factors. Generally speaking, a traditional mechanical advance system can give problems over time as the bushings and springs wear, and you will wind up with erratic timing. On the other hand, simply locking the timing out leaves you with maximum advance at all rpms. If you have ever raced with a locked-out distributor, you are probably aware of how hard it is to crank a hot race engine with lots of compression when the timing is locked at 32 degrees. I’ve seen racers who stalled on the race track, nothing was wrong with the car but they couldn’t get it restarted. They had to get towed back in to the pits, and that ruined their night.
The good news is modern electronics allow you to have ignition advance without dealing with the often troublesome mechanical advance system. For example, our HI-6RC ignition box is really popular with dirt track racers because it has a timing retard baked right into the circuitry. The box automatically pulls 20 degrees of timing out of the ignition up to 600 rpm. At 600 rpm the timing retard is cancelled and you are back to your ideal timing for maximum power. This eliminates the complex mechanical systems normally required to advance the timing but still makes it easy to crank a hot engine–either in the pits or if you have spun out and stalled on the race track.
I’ve been fighting a miss for weeks and can’t figure it out. Any tips for determining if it is electrical?
This is another one that’s really tough to answer without more information, but I can give you some problem areas that often seem to be the culprit. Is the wiring harness high quality with proper connections? Do you have a quality ground in multiple places? Are the plug wires in good condition? If they are questionable, have you used an ohm meter to check for excessive resistance? Have the cap and rotor been replaced lately? Have you made any changes to the system prior to the misfire that can be traced back? If you don’t know the answer to any of these questions, that’s generally a good place to start.
I built my engine myself and it hasn’t been on a dyno. How do I determine the right advance?
You almost always get optimum performance at the maximum amount of ignition advance–degrees before piston top dead center–right before the engine begins to go into detonation. If you are comfortable that you can spot engine detonation, advance your timing in small increments. Once you begin to notice detonation, back off several degrees to give yourself a safety margin and go racing.
Any tips for accurately setting engine timing?
One tip is is to make certain that you set the base timing with the engine revved higher than 4,000 rpm. This is because many ignition units use a multi-strike system that sends more than one spark to the combustion chamber at lower rpm levels to help combustion. That usually stops around 3,000 rpm, and the ignition goes into single-strike mode. The multi-strike feature can create an erratic movement in the timing light, so you can avoid that by revving the engine beyond that range.
Where should I put the CD box?
In a well-vented area away from exhaust and other forms of heat. Make sure it is in a protected area away from mud and debris. Most racers mount theirs in the cockpit or in an enclosed area behind the gauges.
Besides the mounting location, one of the biggest issues I see is making sure you have good leads to and from the ignition box. A digital ignition requires a clean signal. If you have poor quality connectors, it may have not matter with an analog ignition box, but that can cause real problems with a digital unit. Weatherpak or Deutsch connectors are both good options, just make sure you are getting a good connection so that a clean signal can get through.
Poor grounds are also a problem I see on a lot of race cars. You’ve got to be able to provide an adequate ground in order for the ignition system to work properly. It doesn’t hurt to have multiple grounds on a race car. I think racers don’t think about it because adding another ground won’t make you any faster, but insufficient grounding certainly can make you slower.