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Classic/Antique Car Repair/1966 tbird 390 detonation

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Expert: - 5/19/2008


Question
hi, i have a 66 tbird with a 390 motor,I just purchased it and while driving home i went up a hill and the car barley made it.the engine sounded like it had really low octane.i got it home and ran it out of gas,i put in 5 gallons of 93 octane with some lead additive and it does the same thing.when you try to  open the accelerator full it pops through the carb.I checked the firing order it seems to be correct.Is it water?.Also when i start it when it is cold it sounds like the timing is off.Once it starts up and warms up it idles perfectly.I hope you can help thanks!

Answer
The first thing that I would want to see from this car is a compression check numbers for each cylinder. The popping through the carburetor is caused by miss wiring of the plug wires, cracked distributor cap, lean air fuel mixture, or a bad intake valve, weal valve springs, or a worn cam lobe. Take a compression check and check the plug wires and firing order as well for a crack in the distributor cap. Let me know.
Brad

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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