Originally Posted by wag123
Originally Posted by ragtoplvr
I think the 396 should have a TH400, no vacuum modulator.
Quadrajet on ethanol fuel is famous for float getting fuel logged and sinking.
Used to be so common I had a scale. I have not seen it in years.
Rod
1. Big blocks came with the TH400. Yes, both the TH400 and TH350 DO have a vacuum modulator. It is a part that commonly fails and will cause smoking like the OP describes, and it can cause all of the transmission fluid to be sucked out of the transmission. I have replaced MANY of them.
2. The OP has a Edlebrock Thunder 1806 series carb (basically a Carter AVS), not the OEM Quadrajet. If the car was running so rich that it was blowing a cloud of smoke, it would not idle.
007, the PCV valve might have gotten temporarily stuck closed (allowing the crankcase to pressurize), and then eventually unstuck itself. If it were my car I would replace both it and the transmission vacuum modulator. They are both cheap.
THIS RIGHT HERE ^^^^^^^^^