It was getting late when i was making the timing system so thats why i didn;t do the pistons correctly :p
about your engine. 1. nice design +1 2. runs on gas +1 3. the pistons are not in a realistic order -1 4. not all of the smoke gets out of the chamber -0.5 5. nice use of glow +1 = 3.5/5 . that's my rating for your engine. But nice job :D