As a bracket racer, you know it is common these days for true win margins to be measured in thousandths of a second. With that being the case, perhaps it is time we take a look at the last sacred cow at all drag strips, the timing system.

Now before you track operators start ordering rope and looking for a strong tree limb, let me qualify what I am about to say. I operate a drag strip and I have announced quite a few bracket races. So, I know that at every bracket race, someone is going to climb the tower steps, E.T. slip in hand, and complain to anyone who'll listen, "there is no way my car did this!" If it's eliminations, the racer is usually complaining about a breakout or red light. Really ridiculous numbers, such as two-second E.T.s and 700 MPH, are blamed on "a timing system glitch" and the rerun is ordered, or both racers are put back in. If the numbers are close, say a .490 red or a .010 breakout for example, the racer is told, "that's what the computer said, and that's all we have to go by."

Indeed, that is all that they have to go by and you have to think that ninety-nine percent of these numbers are correct. But can a timing system throw out bogus numbers that are close?

If you set up for a .505 and you go .498 red, you probably aren't that surprised. But if you've been several rounds, and feel you have both lanes of the track figured out, a .440 red, or less, is going to send you away shaking your head.

It would be the same scenario for a breakout. If you think you have the track figured out, and you take the stripe by a wheel, a big breakout on your slip is going to make you skeptical.

I had never thought much about any of this until I helped install a new timing system at Ozark International Raceway last year. We chose to go with an Accutime II by Engineered Fabrications. The Accutime was invented and developed by Rusty Crawford of Friendswood, Texas.

Allow me to introduce Rusty Crawford. Rusty is an electronics engineer with a degree from the University of Houston. He also has a solid mechanical background from working as an automotive mechanic, aerospace machinist and sheet metal fabricator. He has 19 years of aerospace experience with the last 14 ½ years in engineering of astronaut trainers and simulators for ASA. The multitude of experience gained from designing a wide variety of hardware from environmental controls, communications, life support systems, and underwater robotic manipulators has given Rusty a vast appreciation for robust systems engineering that must reliably operate in harsh environments.

Best of all Rusty is a bracket racer. He got his start racing his '69 GTO in the Houston area in the late seventies. Rusty made the progression through Pro and Super Pro and the GTO became a tube chassis, big block Chevy, all out bracket car.

Rusty won several track Championships in his area. He began to concentrate on the big bucks races such as the Moroso and Bradenton Five Day, the Texas Shootout and the Tenn-Tuck, winning his share. For a time Rusty built and marketed practice trees and reaction time trainers.

About five years ago, Rusty turned his attention to timing systems. My experience with drag race timing systems goes back a few years when I helped a group of racers buy and install a Chrondek system at Tulsa International.

At Ozark we were shopping for accuracy, reliability and price. I had met Rusty and seen his system operate at Centerville Dragway in Arkansas about a year before.

I was impressed with Rusty's deadly serious commitment to the accuracy of his system. He also wanted to keep the cost down to be affordable for the small and medium size bracket tracks.

Before our installation began at Ozark, Rusty outlined a rough-in procedure which in our case included new cabling. He also walked us through squaring the starting line with the finish line. Rusty then did the final install and showed us more timing system techniques, such as how to properly set the rollout.

Through our conversations, I learned of several things that can effect the accuracy of a drag race timing system, and thought they should be shared with other bracket racers.

What is the biggest threat to the accuracy of any timing system? According to Rusty, it would be the installation and maintenance of the photocells and wiring. (For our story, photocell refers to both infrared and incandescent operated photo switches.)

We are assuming that the timing system, regardless of the manufacture, was properly designed from a systems approach and was capable of accurately controlling the timing of the tree, while simultaneously synchronizing it to a common time base for all left and right photocells.

The System must also as part of system's design incorporate proper methods of rejecting common RFI/EMI and harsh environmental considerations. So what is radio noise (RFI / EMI) and what would be common causes of this at a drag strip?

For our discussion, Rusty stressed RFI and EMI are broad terms used to describe any type of electrical signal that can propagate into and interfere with the proper operation of other electronic or electrical equipment. Man-made sources of RFI that are common to drag strips include, but are not limited to, air conditioners, broadcast equipment/radio transmitters (PA, AM, FM), generators, power lines/distribution circuits, deep fryers, electric motors, lighting systems, and ignition systems. Add to this some natural sources of RFI, static and lightning, and you will find yourself surrounded with varying levels of RFI at all times. Transmission of RFI can come from conduction, induction, and radiation. Conduction is transmitted through an electrical conductor and is typically caused by other electrical devices powered from the same source or data lines. A common misconception is that you are isolating equipment by having them on separate wall outlets. When, in fact, you will most likely have several dozen items interconnected in series/parallel through the breaker box or boxes on the secondary 120-240Vac power lines. It is important that all circuits are properly polarized/grounded and surge suppression and uninterruptible power supplies be added to critical equipment such as the timing system.

RFI transmitted through induction is most commonly caused by power and PA cables run in parallel and in close proximity to the timing systems data cables. Tracks should avoid running the timing systems data cables together with other track cabling, i.e., bundling, sharing conduits and trenches. RFI transmitted through radiation is most commonly caused by high power ignition systems and radio transmitters.

You must assume both ignition systems and radio transmitters will be in close proximity to the timing systems data cables and equipment so it is important that both the timing system and related hardware be designed to function properly in the presence of this unwanted RFI. In all cases, it is important to understand that the timing system data cables can act as a large antenna for receiving RFI. Consequently, it is imperative that proper shielding, grounding, and connecting practices be followed for all timing system data and power cables.

We'll now have a five minute recess for the non-technical to catch their breath.

Something I was always curious about was timing system wiring at a track with lots of splices. Besides reliability, what are the problems multi-splices and junctions can cause? Can they affect accuracy? Rusty told me that each input and output circuit from the timing system has some threshold that determines a high or low state or an acceptable range of voltage/current for other circuits. The best solution is to run the cable continuous with no splices and make the proper connections on each end. Each splice represents a break in the wire that requires some connection method to allow an electric circuit to complete its path to some destination. Your goal is to repair the wire to its original form; however, each splice generally adds some amount of resistance to the circuit at the point of repair.

The greatest problem with splices is that you make a repair or installation and all seems to work satisfactory for a period of time and later when you least expect it, the splice gremlin rears its ugly head. You look up and down the wire and it looks fine but what you can't see is that moisture from condensation and rain, along with dissimilar metals from the splice, has created galvanic corrosion, making that and other splices cause unreliable readings to the timing system.

It is important to properly match wire and connectors for specific applications to ensure the best system reliability. There are several gel filled cable and connector products, such as we used at Ozark, available for harsh environments, such as a drag racing timing system. You see the bulb come on, and your car rolls out of the beam. But what actually synchs the tree to the starting line? This is a function of the total system design as previously stated.

The next time you are truly bored between rounds of elimination's, add up the packages on your last time slip and see if they match what the system prints out as the true win margin.

Our Accutime II at Ozark was the first to use a program that was purposely written for Windows '95. All times, from reaction to finish line were displayed and printed to the ten-thousandths of a second. This included the true win margin.

Yes, I'm a fan of the Accutime II, but I hope the information presented here is useful to all track owners and racers. Because regardless of what timing system is used, bracket racers have the right to a fairly timed race.