Q: How does the gas pedal work? How does the engine respond to my foot on the pedal?
A: It's all about air and how much of it enters the engine. From carburetors to computer-controlled fuel injection, the science has remained the same. Press the pedal and the throttle plate opens to allow the air to get sucked in. Most engines rely on a mass airflow sensor located ahead of the throttle plate to measure the airflow, and then, based on that data, the injectors squirt the right amount of gas to maintain an air-fuel ratio of exactly 14.7 to 1.
A need for speed
Q: I do not understand the constant call for people to slow down and save gas. The stickers on cars in the showroom state the miles per gallon for city driving and highway driving; the latter is always higher. I get better mileage (by far) in highway driving as compared to stop-and-go driving. As I see it, faster, less-impeded driving is more economical.
A: As speed increases, drag, caused by pushing air, also increases. There is an optimum speed above which fuel economy suffers. I could quote the formula that the Society of Automotive Engineers (SAE) developed, but probably only an engineer would understand it. I certainly don't.
What's No. 1?
Q: I own a 1965 Chevy Impala, 283 CID, 4-BBL, 2-speed Powerglide, dual exhaust convertible. I bought it in 2005, and when I go to car shows, there sometimes are discussions as to what car holds the record as the most-manufactured automobile in a single year. I have heard that the '65 and '66 Impalas hold the record consecutively and have, so far, never been surpassed. Can you verify this?
A: I had a 1965 Impala SS, dark green metalflake, 283 CID, 4-barrel Rochester carb, tucked and rolled interior. It was totaled by someone who rear-ended me. I miss that car. Now it's my turn to do the asking: Readers, can you help me answer this question?
Gas puzzler
Q: Is it wise to use no-ox gas in a lawnmower, snowblower and small lawn tractor?
A: By no-ox fuel I presume you mean gasoline without an oxygenate. It is commonly called ethanol. Today's small engines are designed to accept blends of gas with up to 10% ethanol. Do not use E15 (15%) or E85 (85%).
Advice to the lazy
Q: Should small engines on lawnmowers and snow throwers, etc. be run dry at the end of the season, or does that cause damage?
A: Although doing so is a good idea, many of us are probably too lazy to run the tank dry. It is easier to just add some fuel stabilizer such as Sta-Bil, which helps avoid varnish buildup, especially in the carburetor. You can't cause damage by running it out of gas.
Bob Weber is a writer, mechanic and ASE-certified Master Automobile Technician. His writing has appeared in automotive trade publications, Consumer Guide and Consumers Digest. Send automotive questions along with name and town to motormouth.tribune@gmail.com.
