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Classic/Antique Car Repair/1938 Pontiac Opera Coupe 6 cylinder

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Expert: - 10/10/2008


Question
Having the air cleaner off I started the car and what looks like white smoke was coming from the carburetor I could only keep the engine running for short time, about 30 seconds, before it stopped running. What was the white smoke?

Answer
There are three explanations that come to mind. All three are exhaust. First thought is that there is a tube in the intake manifold that separates the intake from the exhaust. This is to heat the air and fuel coming through the carburetor to prevent carburetor icing. If you remove the carburetor you can look down into the bore with a flash light and check the walls of the bore for burn through. The second thought is a jumped timing chain that is throwing the sequence or valve opening and closing off so that the exhaust valve is open too far into the intake cycle. And the third is burned valves allowing exhaust to be pumped into the intake manifold. The later two can be check with a compression test of the engine.

Classic/Antique Car Repair

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Brad Sears

Expertise

All automotive including antique and collectible. However if the car has been modified I can only answer in general terms and maybe get you pointed in the right direction.

Experience

Automotive tech instructor. Syndicated auto columnist 1970's though the early 1990's. Syndicated auto radio talk show, Ask Brad About cars, CBS Radio 70's through 90's TV Show "Last Chance Garage" 1980's PBS-TV syndicated. Auto instructor for the following companies: Fram Autolyte Holly Carter AMF Ford Motor University Of Conn Blue Hills Technical School Sugar River Technical Center Grew up in a family garage in Needham Mass and turned wrenches from the age of 14.

Publications
Manchester Union Leader, Nashua Telegraph, Motor Service Magazine, Yankee Magazine, Popular Mechanics (Saturday Mechanic early 80's), Los Angeles Times, New York Times, and lots more.

Education/Credentials
More than I care to remember. Basically Franklin Technical Institute in Boston, Northeastern University, Fitchburg State Teachers College, Tufts University, and a lot of factory schools along the way.

Awards and Honors
Moto Award winner. And much more.

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