Re: what rpm is my 87 omc 5.7?
I believe those were rated for 4200 - 4600 RPM wot. My recommendation is to ignore the red, however I am curious what RPM your tach says is redline. Just to be clear this is not your recommended cruise RPM, it is the recommended wide open throttle (wot) setting for a properly trimmed boat with average load. Being within this RPM band for those conditions will make for the best overall performance . . . best compromise between top speed and decent acceleration, as well as insuring safe operation at all points in between. If hole shot is your primary goal, you should shoot for the higher end of the range, if tops speed or efficiency are more important shoot for the lower end. Most will say the top end will give you the most satisfaction and flexibility, which I agree with.
P.S. You might get more help with this in the prop section . . .
