We've got what we believe is a 261 in a truck. It seems to be running lean at low rpm. Pull the choke out half way and it's crazy responsive, push the choke back in and you can kill the engine with quick throttle if you would want to. Always has sounded rough at part-mid throttle and occasionally can hear a small pop or miss out the exhaust at idle for as long as I can remember. Carb was just rebuilt. Going to try setting the air mixture with a vacuum gauge tomorrow. Any other ideas? One thing that I have thought of is the vacuum canister on the distributor pulling too much advance to soon. Is that a possibility?
Thanks
