Force 85 Tilt and a few other questions.

[85capri85]

Hello All, New to the site and love it. Already answered several of my questions just viewing other posts. My boat 85 16' Capri openbow with 85 HP Force.

1st. Question: Does the tilt automatically lower at speed? I can tilt my motor up and down at very slow speed, as soon as I speed up the engine starts going down, therefore unable to trim at speed. It seems to hold position on land, doesn't appear to lower itself. Is that normal?

2nd. Question: Does anybody make a stainless steel prop for this boat/engine combination? Engine is bone stock with a SE 300 Stabilizer on it, but wouldn't mind a bit more performance.

A comment on de-carboning. First time out with the boat, about 500 pound load, passengers and gear. All I could get was 31-32 MPH at 4200 RPM. After reading several of the posts, figure I would try to de-carbon. Used about 1/3 of a can of Seafoam and a whole lot of smoke later, the next day out on the lake with 5 adults and gear probably around 1100 pounds (a bit overloaded) I was getting 4800 RPM and a solid 35 mph. Can't wait to get it on the lake with just the wife and I, then open her up and see what it can do.

 

[MWBROWN]

Re: Force 85 Tilt and a few other questions.

Welcome to Iboats.

This site has helped me alot also.


I have a 1984 Fisha nd Ski with a 85 HP with a 13 x 19 prop. I get 5200 RPM with two guys (500 LBS) and gear and a full 20 gal tank.

Tilt should not move under power, unless you move it. I don't know the answer to the problem.

There are stainless props, search Iboats for it. They have them. Also EBAY has them from time to time. Theory is about 400 more RPM with the same pitch. If you but a cupped prop, go down 2" in pitch. SO if you have a 13 x 19 now, aluminum, you could get a 13 x 17" cupped stainless.

It sounds like you are about there with the RPM. You should be able to get about 5200 to 5400 at WOT.

Others will answer you questions that I cannot.

Mike

 

[Frank Acampora]

Re: Force 85 Tilt and a few other questions.

Michigan makes a stainless prop for it. This prop is cupped so you may need to drop down two pitches. I prefer the stainless; I only use my aluminum props as emergency extras! On my 140 Chrysler I get 34 MPH at 49-5,000 RPM with the 17 cupped and 33.5 at 4,400 RPM with the 19 cupped. I have been as high as 36 with the 19 uncupped, but I can't use it on this boat because it ventilates too much in the turns. This boat needs the extra "bite" of the cupped prop.
If you are really lucky, you may find the stock stainless prop. Chrysler had stainless props with no cup for their one piece lower unit (which is the same as early Force) and they give the best performance on these engines. Unfortunately, I inherited my stock stainless and I do not know the manufacturer or stock numbers.
Tilt cylinder does not have enough hydraulic advantage to either tilt or hold engine tilted at anything more than about 1000 RPM. Much over that and the thrust from the prop will press the cylinder down through the built-in pressure relief valves

 

[RRitt]

Re: Force 85 Tilt and a few other questions.

you should have two hydraulic cylinders. The fat one in middle with five sided cover is trim. The tall one that looks like shock absorber is tilt. Frank is right, tilt can't hold motor under power. It is there so that you can get boat on and off a trailer.

Trim is for adjusting the bite of your propeller as the boat gets up on plane. Without trim a lot of your engine power is used up because the prop is pointing down. With trim the prop angle is changed so that all of your power goes into pushing boat forward instead of trying to lift it out of water.

If you have trim and it is not holding then the most likely suspect is pump (aka valve body). It is time for your valve body and motor seals to be dying of old age anyway. I would suspect that tilt might be bleeding down too. If so, then that is actually good news. You can probably squeeze a few more years out of the hydraulic rams and get the system working with just a pump rebuild. If tilt is holding solid but trim won't take power then you probably need your rams looked at as well.

If you don't have trim at all then you should not try to lift motor under power. Sooner or later you'll blow out tilt. It isn't designed to do anything other than help you trailer the boat.