any idea's why my 1980 305 seems to run & idle rough once it reaches normal operating temp, or about 190 degrees

any idea's why my 1980 305 seems to run & idle rough once it reaches normal operating temp, or about 190 degrees


You need to check your ignition timing and make sure it's correct. Does your carburetor have any idle mixture adjustment screws? If it does, try setting them about 2 to 2-1/2 turns out.

Sounds like the O2 sensor has failed, this is provided that your 1980 is computer controlled either carb or injected. Since it sounds like it runs good until it warms up the O2 sensor is telling the computer that the car is cold all the time therefore the fuel mixture is staying rich which is ok at a cold start but at 190 degrees would be too much fuel.

You should be able to pull a code to verify this.

good possibility

Sounds like the O2 sensor has failed, this is provided that your 1980 is computer controlled either carb or injected. Since it sounds like it runs good until it warms up the O2 sensor is telling the computer that the car is cold all the time therefore the fuel mixture is staying rich which is ok at a cold start but at 190 degrees would be too much fuel.

You should be able to pull a code to verify this.

The O2 sensors are supposed to be changed every 30,000 miles back then. I know my '82 calls for every 30,000 miles anyway.