After landing on rollout the engine started running very rough. It turned out that the left carburetor screw had backed out of the intake manifold exposing the intake to atmosphere on the left side cylinders. It appears no combustion was occuring since the egt probe showed only 170 degrees. checked the threads, not stripped, re-torqued to 18 foot-lbs & 1 drop of lock-tite. Restarted & seemed to run fine. Best guess is that the engine ran for 5 min on the right side only. Do you think that there is any severe engine damage ? Plan on flying in the pattern later today or tomorrow. Thanks for your expert advice