Dear Car Talk: 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
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.
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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.