305 inboard OMC sterndrive tilt/trim

[kyriakos@baynet.net]

For the life of me I can't figure out how this tilt/trim unit works. The stern drive has an electric motor that trims the sterndrive up and down. Does this thing have a tilt? I was told that sometimes the engine is tilted by means of a hydraulic unit on the front engine mount but the mount doesn't seem to have anything attached to it. I'm asking this because I can't get the boat to plane up. The boat is a 1975 20 foot Fibreglass hull unit. The little electric motor does not work very well but I was also told to always run it in the down position because of the wear on the ball gears. If I can only run it in the down position and there is no tilt then how do I tilt? Help Please!!

 

[clanton]

Re: 305 inboard OMC sterndrive tilt/trim

The Tilt is only for lifting outdrive for loading,unloading and trailering. The trim was on the engine mounts operated by a hyd pump, the front mounts were small hyd cylinders. Look for hyd pump and lines going to engine mounts.

 

[herman_21060]

Re: 305 inboard OMC sterndrive tilt/trim

Trim/tilt referrs to what the stern drive does in relation to planning the hull, Granted the stern drive has to be in the DOWN position, however it allows you to trim it more or less than<br />90 degrees to force the stern UP out of the water.<br />therefore allowing the boat to reach a planning attitude QUICKER, then you can trim it out for the max rpm's by adjusting it up/or down. OF COURSE this little pump you are referring to has to work properly. I have never seen the MOTOR on a stern drive unit that was allowed to raise or lower.

 

[WSUDERMAN]

Re: 305 inboard OMC sterndrive tilt/trim

kyriakos,<br />I have a 78' omc 305 motor and stern drive unit. Everything you said about the tilt was correct. you should always run with the Tilt completely down! otherwise you will damage the ball gears. <br /><br />The Tilt and Trim are seperate functions that are combined on some models, however, not on ours. They are different/entirely independent systems. <br /><br />In this model year there where 2 trim options. One was called "SelectTrim" and the other was a fixed trim. On the SelectTrim there is a electric motor that drives a screw drive at the front of the motor mounts. This electric screw drive will move the ENTIRE motor and outdrive assembly up and down, based on a pivot point at the rear motor/outdrive stringer mounts. As the front of the motor moves up, the outdrive moves down. <br />The other type was fixed. It has an adjustment so you can change the trim. I believe the adjustment is at the front of the motor just under and in front of the water pump, but i an not sure. you should probably get the cylmer(sp?) manual for these motors and outdrives. Its full of good info!<br /><br />wes