Re: IML: Black smoke out exhaust

My '67 Convertible just developed a strange problem. It has run fine, absolutely wonderful, for days. I drove it to work this morning and it performed perfectly. I had to run an errand at lunch and went out to start the car. It started fine, but the exhaust sounded ever so slightly "muffled". Idle was fine, so I put it in gear and went on my way. Acceleraton didn't feel right, it was as if I was pulling a trailer. I stopped at a stop sign and then pressed the gas to go and a big plume of black smoke came out of the tail pile. I let off the gas and noticed that a slight trail of back smoke continued. The further on the pedal that I pressed down, the more smoke I got.. and now the performance went downhill fast. I had to press the pedal down twice as far as usual, resulting in black smoke just to drive 35 mph. I had only driven 2 miles from work and now could barely top 25 mph with the pedal nearly to the floor... black smoke just gushing out the back end. I pulled over and put the car in park. Black smoke dropped to almost nothing and I peaked under the hood. The engine was idling perfectly. Smooth and no misses whatsoever. I blipped the throttle cable and the engine revved smoothly, but more black smoke out the tailpipe.

So, the engine seems to be running fine, but black smoke gets worse as I accellerate. Car seems to have no power while in drive. Engine revs and transmission does not slip. I backed the car up into a parking spot and scratched my head a bit. Walked around to the back end of the car and the exhaust does sound a bit muffled still. It also left a black patch on the grass just while idling. I rubbed the grass between my fingers and it was sooty, no real fuel smell. No grey smoke, no steam, so probably not rings or a head gasket. What on earth is going on here? My guess was a clogged exhaust, but then it probably would have blown that sucker right off the car when I revved it a couple of times, now wouldn't it? Could it be a pvc valve? Does the '67 440 have a pvc valve? HELP! Thanks.