The last few times I have driven my 69 SS 396 the exhaust fumes have been terrible. I know these cars are not known for their clean burning engines, but mine is much worse than normal. I pulled the plugs and they were all a nice tan color. (I replaced them just in case.). I replaced the points and set the point dwell at 30 degrees. I replaced the wires and set timing with vacuum advance plugged to 6 degrees BTDC. The car doesn’t smoke at all (blue or black). The carb had throttle shafts rebushed and a rebuild a few years ago.
I took the pvc valve out of the valve cover and the engine has little to no blow by. I had a valves job done about 15,000 miles ago. The bottom end of the engine has 124, 000 miles on it. Maybe the rings are loosing their seal? If so, wouldn’t I get smoke and oil consumption (I have neither). I am the second owner. I have never abused the car and the first owner used it to shuttle his family around.

Any ideas would be appreciated. Last time I drove the car I smelled like I had been riding my 2 stroke dirt bike!

The older our Classic Cars get, the newer, new cars get. New cars have no smell at all. When you get used to the new cars, older cars smell bad. My Chevelle has the same problem. I like the smell of old cars. I know this sounds weird, oh well. :D

It doesn't necessarily have anything to do with the engine. I had the same problem in my Camaro, and finally tracked it down to a leaking trunk seal. The fumes were sucked from the tail pipes and through the leaking seal. I found out after I realized that it actually smelled worse when I was driving with the side window cracked open a bit to get some fresh air. Obviously, this created a vacuum inside, which sucked the exhaust fumes into the car. A new trunk seal fixed the problem.

The older our Classic Cars get, the newer, new cars get. New cars have no smell at all. When you get used to the new cars, older cars smell bad. My Chevelle has the same problem. I like the smell of old cars. I know this sounds weird, oh well. :D


"I LOVE THE SMELL OF GAS FUMES IN THE MORNING, IT'S THE SMELL OF HORSE-POWER"..........

"I LOVE THE SMELL OF GAS FUMES IN THE MORNING, IT'S THE SMELL OF HORSE-POWER"..........

Yea, I hear you. I like the smell also, I just don't remember my eyes burning and watering.

The trunk seal is a good idea. I'll check it out.

Dave ,if you motor has a perf cam in it running more duration/overlap than stock your timing is too retartded at the stock 6deg btdc setting you set it too.

This could cause it to run luggy,loosing power,running hotter, and also YES could run richer and stink like heck wasting fuel,it will burn your eyes when it does this. This is due to lower idle vacuum caused by the timming being too retartded which couldin in turn cause the power valve or power piston (depending on carb type)to open at idle or at part/low throttle position when it should not be open. The power circut in the car is only supposed to be activated under heavy load like going up a hill or under heavy open throttle acceloration when throttle is opened and intake vacuum drops loke to 3-4 inches vacuum depeding on setup.

I bet the motor will feel much crisper with more power and and run much better if you bump up the intial timing if it in fact has a perf cam in it. There are not many 35-40 yr old BBC motors that have the stock cams in them anymore so your motor more than likely has an aftermarket perf cam it which you may not be aware of which need a lot more intial timing than a stock GM needs.

So try bumping up your intial timing to apporx 15-16 deg btdc (at 600-650 idle rpm with vacuum adv plugged,re attach vac adv to ported vacuum source on carb after intial timing is set) If it seems to like the advanced timing take it out for a road test listening for detonation and back off the timing a deg or 2 if it does ping to eliminate it. Get on it a couple times in a couple gears up to approx 4800-5k rpms to clear it out and then stop to let it idle to see if it runs cleaner with less odor.

If it does respond well to the intial timing increase but still smells then i would check to see if the power valve(holley) is blown or correct for you cam/idle vacuum or check to ensure the power piston/spring (q-jet/edelbrock type) is not sticking/stuck open.

Too much fuel pressure could cause an over rich cond too,a holley can handle 9psi with ease but q-jets generally like to 6-7 psi on avg so keep this in mind too.

Could be just a float sticking or going bad soaking up fuel (esp on q-jet)and dropping sinking in the fuel causing an over rich situation.

Scott