my 71 350 270hp is running rich I smell fumes when stopped and tailpipes are black it has a holley carb any tips on setting carb thanks

1st before you mess with anything do the simple stuff like make sure your tming is accurate. It should be on your car either 6 or 8 btccheck the sticker by the hoodlatch. Otherwise you'll have to mess with ur holley's adjustment but i really dont know holley's to well.

I apologize for the lack of feedback on your question.

There are a two things that come to mind here.

Is your ignition laying down? Without sufficient ignition you'll just be spitting raw fuel out the exhaust. Check to see if your plugs are fouled.

Is your choke pulling off all the way? If it isn't you'll have the symptoms I mentioned above.

Is your idle mixture off? You didnt mention which carb you have so I can't tell you how to diagnose it.

Good luck and let us know how it turns out.

My 71 also has a Holley 650cfm carb. When I pulled plugs recently they were black. I think it might be the same problem you're experiencing. I also smelled gas when I shut her off. I advanced timing a hair, adjusted the air fuel mix, and put in hotter plugs. It made a lot of difference. More getup, no gas smell. That might be all it will take for you.If you don't know carbs, there's a lot of Holley experts out there that can help you out.

If your Holley is rich before you mess with idle or jets, check and/or set the float level. Pull the sight plugs and see if just drips out. BE CAREFUL AND CATCH THE FUEL. Main cause to run rich. Then make sure the it is not dripping from the shooters which indicates PV out of whack. The timing change and hotter plugs help,but may be masked the real problem. Bet the MPG kind of went south too.