Ever notice that there’s always one guy who’s faster than everyone else? Without any obvious trick parts, he’s a solid two-tenths quicker at the Saturday night bracket races than you, even though you appear to have an identical combination of parts. What’s his secret? Why is he always a fender ahead through the lights? Unless he’s a very adept cheater, the secret is probably all in the tune.
Throwing parts and money at a car will not by itself make a car fast. Even if the parts are well-matched to each other and assembled correctly, the engine still won’t make max power unless the details are optimized and the tune is spot-on. And there’s only one way to tune a car: run after run after run followed by change after change after change. This is where the truly fast hot rodders are separated from those who believe “It’s close enough.” To illustrate just how much power can be unlocked with a timing light and a box of carburetor parts, we took a typical street machine to the dragstrip, flogged the wee out of it and got dirty. When all was said and done, we’d knocked significant numbers off the e.t. slip, added to the mph and made the car more of a blast to drive.
The car we used for testing is a ’55 Chevy owned by Greg Smith. The black shoebox runs a well-built 350 with ported production heads, a 292-duration solid lifter cam, an Edelbrock Victor Jr. intake, a Carb Shop-modified 750 Holley double-pumper (The Carb Shop’s Bracket Master) and 1¾-inch fenderwell headers. The transmission is a TH350 with a 4000-stall converter, and the gears are 4.30s. It’s on the radical side for a street car, but Smith has driven it to work a few times (40 miles round trip) and takes it to cruise nights. We took the car to Los Angeles County Raceway for our tests and did everything on a single day.
The first two runs were made right off the trailer, as the car sat. We didn’t even open the hood. Slicks were used to make sure there were no variables due to traction problems, and a burnout and dry hop preceeded every run. The two baseline passes averaged to 13.38 seconds at 109 mph, with a pitiful (for this car) 2.63-second 60-foot time caused by a bog on the launch. When the day was over, Smith’s best timeslip showed 12.59 at 112.5 mph, which is an improvement of over ¾ second. That’s significant for nothing more than tweaking the carburetor and playing with the timing. We’ve seen far less impressive gains on various project cars after changing expensive parts, such as gears, converters and intakes.
Our day at the track was more beneficial than we expected. It opened our eyes to the hidden potential of this specific car and gave us some good data to pass on to you for a guideline on tuning your street machine. The tuning we did doesn’t relate only to a dragstrip. Every improvement we made at the track was an improvement that made the car quicker on the street as well. A note of caution here: Do your tuning on a dragstrip. That will give you e.t., mph and 60-foot times, all of which can help you tune the car. The street has too many variables to deal with, such as traction, up- or downgrades in the road and stopwatch operator error—not to mention the legal aspects of repeatedly blazing up and down a public street! And always make only one change at a time. If you change two or three things at once, you’ll never know which change was responsible for the difference in performance, and it’ll take much longer to dial in the car.
