Re: Help installing leg on 71 650 merc
Sounds like you may not have had the boat controls and the LU in the same gear or that the reverse lock cam is positioned incorrectly on the lower shift shaft.
Here is a link to the parts list for a 71 650:
MERC 650 - Mercury, Mercruiser, Force, etc. Parts Lookup
See item 55 under GEAR HOUSING ASSEMBLY, COMPLETE (PAGE 1). Scroll down to 55 and click on the picture of the cam and click on it again to blow it up. You will see clearly the sliding cam side and the flat surface on the top.
See item 20 under DRIVE SHAFT HOUSING ASSEMBLY. This is the rod that sits on top of the flat surface of the reverse lock cam when you are in Neutral and Reverse. When selecting Forward gear, that rod comes off the flat surface and slides down the cam face.
See item 46 under CLAMP AND SWIVEL BRACKET ASSEMBLY. This is the pair of hooks that rod 20 actuates when in Neutral and Reverse to prevent the engine from rising up. In Forward gear, when the rod slides down the face of the cam, it unlocks the hooks and the engine is allowed to rise if you hit something in the water.
So it is imperative that the reverse lock cam be installed correctly on the splines of the lower shift shaft and that the boat and LU are in the same gear before installing the LU.
Here is a link to the condensed version of the Clymer manual. Download it soonest to your computer as the link is short lived.
Small Engine Repair Reference Center Home: MERCURY - MERCURY FOUR-CYLINDER MODELS (1969-1989).
See figures M12-63/64 on page 287. You haven't posted your s/n but I imagine you will have the type of cam you saw in the parts list and in fig M12-64 and see the last two paragraphs on page 286.
Gerry
