Dear Car Talk:
Is it necessary to rev your Mustang several times before parking it in the garage? My neighbor insists on doing it, especially at 10:30 at night! — Dee
No, it’s not necessary, Dee.
Have you seen those TV commercials asking men if they have “Low T?” “Have you been feeling fatigued lately? Notice an increase in body fat? Rev your engine excessively?”
That might be what your neighbor is suffering from, Dee. He’s also suffering from NCM; Nostalgic Carburetor Mythology.
In the old days when cars were carbureted — the 1970s and earlier — all carburetors had something called a float bowl. The float bowl is not to be confused with a dessert you’d order at Friendly’s. The float bowl is where the gasoline was stored inside the carburetor while waiting to be released into the cylinders.
There was a myth (probably passed down from your neighbor’s grandfather to his father to him) that if you revved the engine before shutting it off at night, you would fill the float bowl with gasoline and therefore make the car easier to start the next morning.
But that was hogwash, even back then. Well, maybe it was true with his great-grandfather’s Pierce Arrow, but certainly not since.
First of all, the float bowl is already full when you shut off the car. It was designed to stay full, and it would certainly be full when you’re idling in your driveway, not demanding a lot of fuel.
Second, when you start the car the next morning, the fuel pump starts working the moment you crank the engine. So even if your carburetor is old and leaky and you lost some gasoline from your float bowl overnight, the fuel pump would immediately top it up and provide fuel for starting the car.
If your neighbor has a Mustang that’s 50 years old, he’s working off a myth that was never true in the first place. And if he has a Mustang built in the ‘80s or later, then he’s got fuel injection, and even the debunked myth doesn’t apply to him.
Either way, there’s absolutely no mechanical reason for him to do this, Dee. Leave a copy of this column on his windshield and suggest he talk to his doctor.
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Got a question about cars? Write to Ray in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email by visiting the Car Talk website at www.cartalk.com.
(c) 2019 by Ray Magliozzi and Doug Berman
Distributed by King Features Syndicate, Inc.