Someone tell me what this plug is reading 85 camaro 305 quadrajet Having carb problems doesn’t wanna idle real choppy , runs fine when your on the throttle but makes a loud back fire threw exhaust on decel when under load These problems just started happening few days ago I rebuilt the carb probably a month ago and everything worked perfect clean idle crisp throttle response Figure I’d pull a plug see what’s going on but I’m not to good at reading them lol

 

Rich

 

Agree. Looks long-term sooty to me.

Probably leaking metering jet well plugs, like everybody else's.

Backfire in the exhaust when suddenly releasing the throttle after hard loading is somewhat normal. With a carb, it takes a certain amount of time for the fuel flow to change to match the air flow, and at such moments, there will be greatly excess fuel being fed. It doesn't all burn and some goes all the way through the motor and lights off in the exhaust instead. A rich idle circuit will do the same thing. As will leaky metering jet well plugs. Basically anything that allows excess fuel into the motor at high vacuum will result in popping in the exhaust.

 

Heat range is good looking at the ground but with the amount of soot on the ceramic, it's way too rich.