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My 68 lemans has been sitting in my garage all winter, and we start it up and let the engine run weekly, but we havent driven it anywhere. Now the roads are clearing up so i decided to take her for a spin and when i give it a little gas it starts making loud popping noises in the rear of the exhaust (not like the engines got a knock because it doesnt do this contiuously) and it sounds like somethings banging around in my trunk (nothings in the trunk), also it feels as though im gonna stall out but then it doesnt, and theres also black liquid coming out of the exhaust, What could this problem be?
 

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I'd guess back pressure from carbon build up. My Chevelle does the same thing sometimes, but normally stops after 1/2 an hour.
 

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No Advance

You also might check on your spark advance. There is both vacuum and centrifugal advance in your distributor. Open cap lift rotor, then spray a little WD40 on the centrifugal mechanism. Work them back and forth a few times; also work the vacuum rod a few times to insure it’s free. Then put things back together and insure vacuum hose is connected to diaphragm. Start engine and try it out again.
 

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The black liquid type fluid that's coming out of your tails is more than likely a combination of it running rich/warming up/condensation in the muffler. And what you describe sounds like a random backfire from a miss. Check your plugs and dwell.
 
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