What Happens in the Tech Shed?
Part 2 - What to Expect in 4 Cycle Tech

 

By John Copeland

In the March 2001 issue we took a look at what goes on during the tech procedure, specifically for 2 Cycles. The article also talked about some of the general guidelines for administering tech in a fair, even-handed manner. Remember, tech is a right, not a punishment. It is how a racer confirms to their competitors that he/she beat them fair and square. The 4 Cycle racers face a number of issues, tech-wise, that do not concern their 2 Cycle brethren. So let us take a look at what happens when it is time to face the 4 Cycle tech man.

As with the 2 Cycles, fuel tech is usually the first thing on the tech man's list. Do not assume that just because there was a pumparound there will not be any fuel tech. If he asks for a fuel sample to test, racers should give it to him promptly and cheerfully. (In fact, a cheerful, helpful attitude will go a long way toward making time spent with the tech man a lot more pleasant. He's got a job to do and believe me; he will hear more than his share of whining and complaining before it is over, so racers should try to be one of the good guys. It will pay off.) For those who are running in a gasoline fuel class, fuel tech will be much like the 2 Cycles. If they are running in a methanol-only class, the procedures are different, but pretty simple. Racers should always study the tech manual to familiarize themselves with the proper procedures. That way they will know what to expect, and there will not be any question about whether the tests are being properly done. Usually fuel tech begins with a visual inspection. Pure methanol should be clear, with no color or cloudiness. Racers need to always check their own fuel before each trip to the track to make sure it has not been contaminated somehow. Anyone would hate to have all their hard work ruined because something accidentally got into their fuel jug. The most common fuel test for methanol is the "water" test. A measured amount of the fuel to be tested is added to a know quantity of distilled water. Unlike gasoline or oil, water will mix with methanol to a certain degree. The tech man will be looking for a line of separation between the fuel sample and the water. Where that line of separation is will tell him how much of the methanol got dissolved in the water. He will also be looking for any unusual appearance, cloudiness, color, etc.

4 Cycle tech inspection can also include checking the engine oil for any illegal additives. Again, the procedures outlined in the tech manual pretty well describe what racers should expect. Many tech inspectors arc now using a "sniffer" designed to look for refrigerant leaks in air conditioning systems to "smell" the oil in the crankcase. Additives added to the oil or introduced into the crankcase can cause the sniffer to go off. Here is a word of warning; fuel does get past the rings and wash down the cylinder wall, especially in the restrictor plate classes. It is critically important that racers change their oil after every heat. Otherwise, the fuel from the cylinder walls may contaminate the oil and cause them to fail oil tech. Besides, diluting the oil with fuel is hard on the engine. Ask your engine builder. The other most commonly used oil test is to take a sample of oil and put it in a common tablespoon. Then the oil in the spoon is heated. Once the oil is hot, it may burn when a match or lighter is put up to it, but if the flame continues after the match or lighter is withdrawn, it is determined to be illegal. Racers should not take chances. Racers should only use the commercially available oil their engine builder recommends, and they need to change it often.

Once fuel and oil techs are completed, the tech man will likely ask the racer to remove the engine from their kart so he can begin the rest of the tech procedure.

If you review the tech procedure checklist for 4 Cycles, it is easy to see that checking every item on the list could take hours. Unless a racer is competing for a National Championship, or has done something to stir the tech man's suspicions, they will probably have a much more abbreviated examination. A word of advice here; once the engine is off the kart, a racer should wait for the tech man to tell them what else he wants them to do as far as disassembly goes. They should not start taking things apart until he tells them to. Getting over-anxious will only make it look like a racer is trying to hide something.

Rather than crank through page after page of items to measure and examine, the tech man will likely pick out a few of the most common areas to inspect and leave it at that. Usually that begins with the carb and fuel tank.

Like a lot of the items the tech man will check, teching the carb and the fuel tank will involve a combination of measurement with pogo gauges and visual inspection. Things like the carburetor air intake horn, the venturi size, and metering hole sizes should all be checked with the proper no-go gauge. As we discussed last month, these no-go gauges are precision measurement tools sized just slightly larger than the maximum allowable size for each particular specified area. If the no-go gauge does not fit into a particular opening without forcing, the dimension is legal. There is nothing wrong with watching the tech man check these dimensions. He should handle both the gauges and your engine parts carefully. He will also visually inspect for signs of tampering or other illegal modifications. If everything checks out, the next step will most likely be to remove the cylinder head. It is a good idea to have a small collection of tools at tech to disassemble the engine as needed. The tech man may have the tools required, but it is usually a better idea to have your own rather than to keep asking to use his.

Once the head is oft it is short work to measure the clearances on the head for minimum legal heights with a depth micrometer. That and a quick visual inspection are generally all that is needed. Then it is time to pop the valves and valve springs out. Like the other parts, these will get a visual inspection, and then the springs will be measured with a caliper for length and wire diameter. The valves each have a no?go gauge for overall diameter as well as specifications for seat angles and valve stem diameter. Besides, the tech man needs the valve springs out so he can drop the valves back in without the springs and set up to measure the cam specifications. Checking the valve opening and closing times, relative to crank rotation, is called profiling and, while it is impressive to watch, it is really not all that complicated and does not take an experienced tech man all that long.

Cam profiling begins by attaching a degree wheel, a disc marked in 1?degree increments, to the crankshaft. Then a fixture is mounted to the head with mountings for dial indicators over the piston and each valve. The tech inspector will rotate the crank until the piston reached the top of its travel in the cylinder, Top Dead Center, or TDC. Then he will adjust the degree wheel to show the pointer at 0 degrees, Top Dead Center. Finally, he will slowly turn the crankshaft, noting at how many degrees past TDC the valves open, and how much they open as crankshaft rotation continues. He will check how far they open at maximum, and when and how much they close. The acceptable figures are in the tech book,, and are also generally printed right on the degree wheel itself. That makes it faster and easier to check and that is good for everybody.

The last of the common tech inspection items to check will be the ignition system. The first step is to remove the flywheel and weigh it. The Shp Briggs flywheel has to weigh a minimum of 14.7 pounds to be legal. A quick visual inspection and then it is on to the ignition coil. Other than a quick look-over, the important spec here is electrical resistance. Measured with an electrical meter called an Ohmmeter, the resistance across the coil must be at least 2000 ohms, but no more than 5000 ohms.

That about covers the most common tech items. Of course, in a National Championship (or a big money race), tech can be much more extensive. The tech man is perfectly within his rights to remove the side cover and extract the cam, the lifters, the piston & rod, and even the crank itself. The point is, all of these items are carefully specified in the tech book. 1 cannot over-emphasize the value of a racer getting a current tech manual and carefully reading it. Not only will it give them a good idea of what to expect when their turn comes in tech, but it will alert them to what the tech man should be doing and how he should be doing it. If a racer sees something that they do not understand, or that is not the way it is called for in the book, then they should politely ask the tech man what he is doing or why he is doing it that way. If they do not get a satisfactory answer, ask him to stop until they can confer with another major official at the track. There is no reason to get hostile or aggressive. Racers need to keep their cool. Usually everything works out fine.

In the unlikely event that the tech man finds something amiss, racers can politely ask him to show them the discrepancy. They may also ask to review the specification in the tech book, and then verify again that the item in question is or is not within the rules. Keep in mind that tech men arc human too. (I once saw a racer almost disqualified from winning a very prestigious race because the tech man accidentally picked up the wrong size pogo gauge and in it went right into the hole he was measuring. When the competitor asked, the tech man checked the specification in the book, measured the no-go with a micrometer, and discovered his error.) Now here comes the hard part, if something comes up illegal, racers should try not to take it personally. Most disqualifications in tech are not for deliberate cheating; they are for minor, accidental oversights. The tech man (and your fellow racers) are not going to label anyone a cheater just because their engine builder cut the head a little too close or missed the cam profile by a degree.

Remember, most tech inspectors are honest, dedicated volunteers who have agreed to forego the fun part of karting to contribute a vital service to every racer at every race. They want racers to be legal. Their job is to assure competitors that, win or lose, every racer has earned their position fair and square. And believe me, there is no greater pleasure for a tech man than to reach out and be the first one to congratulate a first-time winner. Walking out of tech with a big smile and a box full of engine parts tells everybody that a racer won with hard work, set-up talent, and driving skill.

Finally, some words about tracks that do not do tech. DO NOT RACE THERE! Some clubs and tracks have the mistaken idea that not doing tech is a good thing. Nothing could be further from the truth. Racers who suspect that they are getting beaten by drivers will illegal equipment are not likely to return to that track. People get involved in karting because it is a (relatively) low-cost, fun motorsport. If they go to a new track and, because there is no post-race tech, thinly they do not have any chance to be competitive, they will not come back. Year after year, we see that the dribs and tracks that run a fair and reasonable tech program every race continue to grow and to draw more dedicated racers. The tracks that do not have tech seem less professional, less stable, and are more often the ones that eventually close down. If the track does not perform tech, racers should ask them why not. If they say no one there knows how to do it, racers can study up and volunteer. If they still are not interested, it is best for racers to find themselves a new place to race. Tech is the framework that we all have to live and work within. It is how karting has maintained the "level field" that helps make our sport work. And it is how we validate the accomplishments of our winners. I cannot wait for you to get there yourself.

In closing, I would like to take a moment to acknowledge the help of two gentlemen in preparing these tech articles. Tom Speaks and Pete Tyer are WKA certified tech inspectors. More importantly, they are dedicated professionals. If it is ever your privilege to set your engine on the bench in front of either of these two, you will find them to be knowledgeable, easy to get along with, and utterly fair. Their insights, courtesy, and good humor have, I am sure, helped many nervous karters through their first tech inspection. It has been my good fortune to get to know them and to take advantage of their experience in preparing these articles. Thank you, gentlemen.


Next month National Kart News will have a sneak preview of a couple of new tech wrinkles. WKA has some new gadgets to help keep everybody "playing by the same rules." See you then.