I have been working on my 1978 evenridue 140hp. I finally had it running like a champ. My last trip I was running almost full speed and ran out of gas. Ever since then cracking has been very sluggish. I removed the spark plugs and manually turned the flywheel and could tell there is resistance. I was going to pull the heads off this week and check the pistons and rings, but didn't know if anyone had other suggestions.