Q: 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
A: 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.
Carburetor care
for ’60s Chevy Nova
Q: I have been working on my 1966 Chevy Nova II. I recently replaced the fuel pump (mechanical), all filters, all spark plugs and liquids. I’ve also tried tuning the idle speed and idle mixture screws on the carburetor.
Unfortunately, the car still stalls on occasion when trying to accelerate quickly or brake quickly. Could it be that the carburetor needs better tuning? Or perhaps it needs to be completely rebuilt and cleaned?
Any feedback would be greatly appreciated.
— PETER
A: If you can find a new carburetor for this car, buy it, Peter. In fact, buy two, and save one for 2029 because it sounds like you have two carburetor problems.
If it’s stumbling or stalling on acceleration, that’s probably a bad accelerator pump. That would cause a lack of fuel when starting from a dead stop. And if it’s stalling when you brake hard, that could easily be a bad carburetor float, which becomes porous, gets submerged and causes flooding and stalling.
While you could take it apart and clean it and replace the accelerator pump and float, carburetors are notoriously finicky. It’s not only a lot of painstaking work with lots of small parts, but it might be one of those jobs where you have parts left over when you finish and have to wonder if they were important (hint: they were).
It’s much easier to simply replace the carburetor, and I can pretty much guaranty that’ll solve both of your problems.
You might be able to find a new, original Rochester carburetor for this car if you search online. They used to be a dime a dozen. If you have trouble finding one, or it’s too expensive, a professionally remanufactured carburetor would be almost as good.
And if you can’t find either of those, you can buy an aftermarket carburetor for this car from a company like Holley. That would probably require you to change the intake manifold as well.
So, depending on your level of mechanical skill, it might be something you want to have a mechanic do for you. Or, if you have enough surplus vacation days and Band-Aids, you can tackle it yourself. Good luck, Peter.