Sorry if this is a redundant post. I've read numerous that mention nearly the same problem yet could not find resolution (a reply saying "this was the problem") in a single one...

'79 L82 (350) that except for a replacement intake manifold (Edelbrock) appears completely stock. All original intake installed and functioning as well as all original emission controls. The spouse gave it to me about 10 months ago in an inspected, licensed and running condition. The only "work" I've done to the engine is to replace the spark plugs (fine looking but VERY old) after which both starting (save the problem below) and running became excellent.

Problem: After at least 12 hours sitting I get a hard start. If I do nothing but crank for about 10 seconds and then follow factory starting instructions for a cold engine it will start and blow white smoke for a couple seconds before it dies (ultra rich, right?). If it sits for a few hours it starts perfectly but more than once people have asked, "Why does it stink?" While weather is now warm, even with a semi-cold engine (say 8 hours since last run) it starts perfectly--maybe 1/2 second cranking without touching the accelerator but--the longer the time since last run the more chance it will stink or stall.

Question: Do these symptoms point directly to leaking plugs in the carburetor fuel bowl?

 

It could be that, or it could be a check valve in the accelerator pump circuit not closing and siphoning your float bowl dry as it sits. At least I'm pretty sure it's the accelerator circuit, been a while since I have had this problem. the stuck check ball issue I had was about 24 years ago.

Either way, I would take it off and rebuild.

 

Setting 12 hours, sounds like the float bowl is getting drained- either the well plugs or a fuel filter without a check valve. And right after that, from your description, I'd say the choke pull off is dead or needs some work.

Stinking after a hot restart sounds like the float/ needle & seat, are not adjusted properly. Float may be saturated. Hot shutoff, gas is dripping over into the intake from the main metering in the carb.

 

The "stink" and "white smoke" indicates burning antifreeze so you need to have your cooling system pressure checked. White smoke is also a sign of burning ATF and that would be caused by a bad transmission modulator valve.

 

Thanks all! I'll address the carburetor issues as soon as time allows.

tobroketoretire: I recently had a head gasket issue (actually bolt issue but that's a long story) in my STS that caused coolant to collect in a cylinder or two after it sat a while. I know the smell of burning coolant very well and this is not the same as I've caught a whiff at least once. To me coolant has a oddly sweet scent when burning while this is a putrid smell.

 

Then you might have a modulator valve failing because burning ATF will create white smoke with a foul odor. Are you having any shifting problems? If so then a failing modulator could be the cause. Its sure worth checking.

 

Shifts and downshifts are both fine. Connections at the rubber hoses that lead to the transmission cooler were leaky and I replaced them very recently. I'll keep an eye out for any drop in the fluid level.