The automotive world fundamentally changed in 1993. This was the year the last carbureted street car or truck was imported into the United States. A carburetor is a mechanical device for mixing air coming into an engine with gasoline to form a combustible mixture. Every car sold since then has used fuel injection – an electronic system that more accurately meters fuel. This reduces emission, increases fuel economy, increases power, and increases reliability. All in all, it was a big win for consumers.
There are fewer and fewer carbureted cars now running around because of this shift to fuel injection. Most carbureted cars have by now met the crusher. The ones that are on the road are usually classic or hot-rodded cars. There are a select few cars still running around that were built between the 1980 and 1990 years. These were the computer controlled carburetor years and, man, were they complicated.
The number of people who are qualified to work on these cars is dwindling rapidly. There’s always been the thought that ‘any real man can rebuild a carburetor’. Sure, anybody can take something apart and put it back together but can they make it run right? The answer is definitely ‘no’. As someone who started in the industry when carburetors were still in full force, I can tell you that even back then there were few qualified people to work on these cars. If you could find a mechanic who could get your car running perfect, you held onto him and developed a long term friendship.
I am a big believer in using the right tool for the job and this includes tuning. Tuning consists of optimizing fuel mixture and spark advance curves with the goal of maximizing power and ensuring good drivability. Throughout my career, I’ve worked with guys who have claimed they could ‘tune better by ear’. This was a poor excuse levied by those who did not know how to use the equipment.
When I started out in this business I had just finished three years in school studying automotive technology and had learned to use these machines to diagnose poor running problems. This was a huge advantage to me because I was entering the workforce in a time when customer satisfaction in the industry was very low due to incorrect diagnosis. Within a month of working in a real shop, it was obvious that most of the other mechanics in the shop did not know how to use the equipment and had terribly bad times getting cars to run right. I was diagnosing problems more accurately than anyone in the company and luckily the boss noticed.
I prefer Sun equipment. Sun was an automotive tools company that made diagnostic analyzers from the 1940’s up until the 1990’s when they were bought by Snap-On Tools. In the 60’s, 70’s, and 80’s they were the de facto standard when it came to shop equipment. A shop normally had several Sun Scopes, as they were called. These machines were comprised of ignition oscilloscopes, cylinder balance testers, dwell meters, tachometers, vacuum gauges, condenser testers, etc. and were invaluable in diagnosing and tuning these old cars.
Fast forward 25 years and I am still using the same equipment to fix cars when the rest of the world has gone to handheld diagnostic scanners with wireless information systems. No computer will help you fix and tune carbureted cars. The equipment we used back then was analog and is still the best on the market for its purpose. I am lucky because I have 3 working Sun engine analyzers, a Sun distributor machine, and a portable gas analyzer.
There are very few people still around who are qualified to work on these cars. There are probably a handful of guys in the San Francisco bay area (where I live) that can do it. Consumers have come to expect their classic cars to have a certain amount of flaws with respect to the way the engine runs. I can’t tell you how many times someone has said, “It runs great, except . . .”
Using the gas analyzer to monitor exhaust carbon monoxide (CO) level and hydrocarbons (raw gasoline that has gone through the engine unburned) in combination with the Sun ignition analyzer really helps me get an idea of what is going on inside the cylinders. Using this I can see if the mixture is too lean or too rich, if there is a secondary ignition related misfire, or a mechanical misfire. The dial advance timing light allows me to plot mechanical and vacuum timing curves at set base timing. The scope has a built in dwell meter but I can read what the optimal dwell should be by looking at the scope pattern – this is not something most people would do. I picked it up from my scope instructor, Les Schwoob (an absolute carburetor master).
About 90% of the time we are able to get the cars running better than they would have when they left the factory. This is due to my boss’ and my extreme sensitivity to drivability problems. We spend hours ironing out small flat spots in the torque curve that almost no one else would notice. We might spend 40 hours just tuning the car until it is perfect. This would be about $5000 dollars if we were charging the customer. However, due to the extreme prices of the cars we sell, this is relative and is one of the reasons we can charge as much for a car as we do.