btolton

Hello
Has anyone had a problem of black smoke coming out the tailpipe, the carb is not running rich. it just bows out on the start up & will show up at idle as well. the carb is a holley 600 brand new just swaped it out with another holley still does it even worse. the car also hard to start after sitting for a few days & car has stalled out out on me when driving on hot days & after its been running for a while. any help would be appreciated
thx brian

Oldsmaniac

Black smoke is ALWAYS raw gas of excessive quantity being induced into the cylinders. How can you say it is not running rich?

1970-W30

Your Carb is feeding more gas to the engine then it needs, that means it is running rich. Check your float level on the Holley carb.

76olds

A year make and model would be helpful as its your first post. If your engine is equipped with an EGR, that could be your problem. If so hit the EGR valve with a hammer and see if it runs better.
Again more info on your car would be helpful!! We all like pics as well.

MDchanic

Oxymoron of the week, like "jumbo shrimp" (unless your car burns bituminous coal).

+1 to all above.

Welcome to ClassicOlds!

- Eric

oldcutlass

Or diesel fuel... +2 with above.

btolton

I have a 73 cutlass supreme with a 350.
I have had the top half of the motor redone.
new valves, edelbrock intake,valve springs,roller rocker kit,comp cam,hei distributor,7a heads all redone installed advance curve kit as well & holley 600 carb.we have installed larger jets in the holley as well.The car runs very good & strong. i have two issues 1 very hard to start after its been sitting for at least 3 or 4 days. 2 black smoke out the tailpipe when I step on the gas like its running rich, also after start up alot of vapour coming out of the exhaust with alot of blackmixed in.I brought the car in to my engine builder & we put a o2 sensor on the exhaust to see if its lean or rich it was actually a little lean, also pulled a couple of plugs & they were fine. we have disconnected the choke to see if it was the choke sticking but I tried it yesterday & still the same result. with the black smoke & black vapour. Brian

Oldsmaniac

Well either your buddy's Exhaust gas analizer is shot or gremlins are stuffing carbon powder in your tailpipes each night.

m371961

+3 Black smoke is over fuel / lack of air. I assume you tied/adjusted choke to full open when disconnected. Your discription of your problems all point to choke and or carb trouble. I would go back to original jets, double check float levels, choke adjustments ,and carb for internal leaks

pogo69

lol...the 'uncle buck' car