I'm kinda new to boat motors so i need alittle help. On a 1973 evinrude 18hp (atleast thats what i was told it was not for sure though) it felt like it was missing at the lake (on it first test run since i've had it) i brought it home and put new plugs in, then took it out a few days later and it still sounded like it was missing so i popped the cover open ans seen that the bottom plug was lose so i tried tighting it back up and it berely caught so i tried starting it again and it popped out and come to find out i've been running on one cyl. So me question is what are the right plugs for this motor and are the 2 plugs different sizes or am i going to hve to repair the threads? Thanks alot Cory
