just rebuilt my 305 (700 miles on it now) look at my signature when i get down on it and then let up on the gas a pyff of black smoke comes out the tail pipe what is it and what can be done to fix it thankz

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92 camaro 25th anniversarry polo green with 2 gold stripes stock 305 tbi

89 camaro
white
92 ground effects
cowl induction hood
tinted windows
accell plug wires
K@N filter
305 from 92 camaro
carburated
bored .030
flat top pistons
larger valves
zz4 cam
heads shaved

 

might want to lean it out a bit, and check ur plugs & ignition, i'd check the ignition before leaning though