2 Questions ... Prop and Power Trim ... 150hp Force Outboard

[sshotgun]

First let me give you a little info on the motor ... I just bought a 1990 Force / US Marine 150hp CFI Outboard Motor that was still new in crate .... other then maybe at factory , it has never been ran .... Model # 1501X90C .... Ser. # 020451 .... It is installed on a 18.5 foot bass boat ... and has had about 2 hours running on it so far ....


1st Question .... while running at a slow speed the trim moves the motor up and down fine .... anything past 1/4 throttle .... the thrust of the outboard pushes the motor back down ... it won't hold itself up under power .... Fluid level is OK and I have tried to bleed air out of the system several times .... any ideas for me on what is the problem ??? Maybe a O Ring problem ? .... Remember , it is brand new / old stock motor ....



Question 2 .... This was a ... Ah CRAP !!! moment .... I was told to go to a 19 degree pitch S/S prop from the stock 17 degree pitch prop to get my RPM in the range it should run at WOT .... I bought a Solas Amita 3 S/S Prop ... 13 1/8 X 19 degree ....



It slipped on just fine , BUT , the edge of the prop just barely hits the Trim Tab ... ( as can be seen in pictures ) .... Is there a different Trim Tab I can get ? ... Or can I cut a notch in the trim tab so the prop doesn't hit ?? Any ideas for me ?



Thanks ...... Doug

 

[Frank Acampora]

Re: 2 Questions ... Prop and Power Trim ... 150hp Force Outboard



Doug:Welcome to the forum. These trim systems are two cylinder. The center cylinder is trim only and will hold trim against engione pressure. The second cylinder trhat looks like an auto shock is tilt only and will not hold against running pressure. It is designed to tilt the engine for beaching and trailering only. It has relief valves inside that do bleed down when excess pressure is produced. Thus, if you gun the engine much past 1000 RPM, it will push down until it contacts the trim cylinder.

As for your prop: If you are willing to do a little work and spend a little more money, you can fit it without notching the exhaust snout. I needed to modify the thrust washer on a Ballistic prop I bought. Look for an older post of mine on this, but here are some photos. Notice that I replaced the stock thrust washer with a stainless split collar--that cost 35 bucks at Fastenal. That and a couple of thin stainless washers gave me prop blade clearance of about 1/8 inch and spaqced the prop out so the hub did not contact the gearcase casting.

Of course,My engine is an earlier model and does not have tru-hub exhaust. You may need to do some other mods, but the principle is the same.