I have a pair of Ford lehaman 120's from 1969 running my boat. They were beginning to smoke more than usual. A mechanic suggested having the injectors rebuilt. I did that and he did the removal and reinstallation on the engines. It still didn't run well. And now was hard to start. But he said all it needed was running hard for 30 minutes to "clean" them out. That did nothing and the engines were still difficult to start. Turns out the mechanic failed to set the timeing properly and it was a cog out... So now I'm worried that I damaged the engines by running them hard with the timeing so far off. Anyone know if that could have caused permanent damage? Incidently, it still smokes more than it should. So the injectors was a waste of money... Except that it eliminated that as a possible cause.