Hey guys here to pick your brains a little, I installed a new Holley 2bbl 500 cfm carb,and it runs fine according to me,but the tail pipe of my exhaust have turned black inside,like if a rick condition exist, but my plugs read lean, plus I get this gas smell wen the truck is at idle,what do you guys read wen you look at this plugs?Here are some pictures. Thanks in advance for your input.

 

Very lean at lower rpms, might be on the rich side at the higher end though. Get it up to temperature, then do a hard run and shut it down quick, without idling. Pull a couple plugs to see then, but use caution restarting since it'll probably backfire.

 

Today's fuels give a different plug reading compared to non ethanol gas.