engine height
 

I think my motor is too low, tons of spray when underway, Engine is mounted through the top hole 25" shaft, cav plate is under water when going fast, I can't see it. Here are some pics when i am going about 2000 RPM

You need to lok at it when your on plane. you want the lower cavitation plate(the one just above the prop) to be at the waters surface. Just above the surface gives the best performance, but I like to set em so that it runs just below the surface about a 1/4-1/2" so I can keep the prop burried when in rough water. But you should still be able to see it when your on plane.

Thanks, yeah when I am on plane it looks about 2" below the surface, You might have seen all my past posts trying to find out my RPM problem (4200 Max) and speed issue (32 MPH on GPS ), It sprays up water pretty good when going 4200 wondering if this could be creating drag, the pic's stink. Do You think I should move it up 1 or 2 holes? I will try to get better pics over the weekend. Thanks

I hear what Ferm's sayin' about stayin' in touch in a rough sea...but I like mine to be about 1/2" above the water on plane...least amount of drag, better fuel economy and top end...as long as YOUR BOAT will handle it that high...some will "blow out" in a turn...whether you like 'em like mine or Ferm's, sounds like yours can go up some...I think you'll like the result...

BTW...do you know how to raise/lower the motor using the trailer???

I have seen before that if you put a straight edge on the very bottom of your hull and extend it out to the cav plate on the motor you can determine if your motor height is correct.

I think the formula used is for every 12 inches the front of the motor is away from the transom, move the cav plate up one inch from level with the bottom.

Of course you have to get the hull bottom level and the motor straight up and down for this.

I have mine mounted with the cav plate even with the hull bottom, a little low, but it never breaks the prop loose no matter what.

This works good on MERCS and YAMAHAS, but I have found it to result in overheating for OMC's. OMC's really need to be level with the bottom of the hull on the older ones as the water pick-ups sit pretty high. And if it is a SUZUKI you MUST have it mounted so teh cavitation plate is just below the surface or else you will FRY the engine as they use dual pick-ups(one on the side of the foot and the other is underneath the cavitation plate).

Sounds like RB has his Zukey in the right place then...all this time, I'm sure he does...

I tried droppin' the Johnson...one notch, then two til I ran outta notches...felt like the foot was draggin' bottom...LOL!!...still ran hot, so in my case, it's something else...Dr Spare will get the patient up and runnin'...I goin down to his clinic Sun...and he'll see us 1st thang Mon...

Here are some pic's I took today of my engine while going 3,000 RPM's Looks Too low to me what do you think ?

I would go up 2 holes and retry it.

Thanks, should I worry about the space there will be between engine bracket and the top of the transom ? I had my ear to the motor while running 3,000 RPM and I hear what sounds like a rattling, sounds like it is coming from the lower unit, could there be something going on down there to cause me not to get my full RPM's. I am still trying to find out why I can't get my RPM's (only 4200 ) my prop is 15-1/2 X 15 dinged up a little ( Alum. ), the engine is a little low, I checked all carburator items, all OK, could it be a combination of all these things ? what could I do to check out the lower unit ( if anything ) ? Thanks

Joker, I agree w/Ferm about raising two notches...I wouldn't worry about the gap you'll create by raising it...

Although I have advocated using large diameter props for these boats, I also know that while it worked on mine, it may not be best for all...first, raise the motor and see what difference(s) that alone makes...if yer still hearing the rattle and sure the noise comes from the lower, you might try a smaller dia prop...try to make only ONE change at a time...that way yer not scratchin' yer head over WHICH change made the difference...

Hope yer not losing any lower unit oil...have you pressure tested it?...

Rattling on those motors (I had one) is often due to the magnets under the flywheel coming loose...knowing sometimes it's hard to isolate noise, could it be coming from up top?...just thinkin' out loud...

Thanks, I will try these changes, I'll check my lower unit oil, but I never had a problem with leaking, the reason I am wondering about the lower unit is that when I got this motor the mechanic told me it was a year newer than the rest of the motor. So I am wondering if something is loose or something, maybe in the spring when I have my water pump done I will ask my new mechanic to take a look.

I also agree with the experts, raise the motor.

Along the "dinged prop" lines. This past summer I hit a tree or log or something wooden over at Jordan Lake (I was in the marked channel but water was so low I hit something).

Right away, my cruising speed dropped by about 7-8 mph with what looked like a simple "dinged prop". It also started making noise because the prop was out of balance.

Put on my spare prop, instantly back to normal.

Just something to think about.

x3 on raising the motor. Fix the prop, service the lower, and check the latches on the outboard cowl. My Johnny started to rattle and it turned out to be the latches. Glued in a thin piece of rubber to keep the latch quiet. Lost the rubber and discovered that the silicone caulk served the same purpose. Found it while poking and prodding around back there while on plane, actually put my hand on it to keep my balance to lean over the back and the noise went away. Second best guess would be the exhaust can rattling around if the mechanic didn't put it all together correctly, maybe he forgot the rubber at the bottom of the exhaust where it goes into the lower.
I do not believe you will see many more RPM from motor height adjustment. Something else, maybe the prop, your rpm is off by over 1000.

Well pulled the boat for the season today, upon inspection I found the cause of the rattle. A while ago I had a rattle and found out it was my trim rod rattling when I went over 2000 RPM's because the water was pushing up against it. I used 5200 all around where the trim rod goes through the bracket, rattle was gone, used it all summer, no rattle. Well the 5200 let go and the rod is loose again. I think when I raise the engine I won't have the water forcing up against the rod and therefore no rattle. By the way do I need that trim rod? it doesn't seem to do anything, even when I lower the engine all the way down it doesn't touch. Thanks

I'm trying to picture a "trim rod"...:head:

At the botom of the engine bracket there are 6 holes ( two rows of three ) on approx. a 45 degree angle, there is a stainless rod ( about 5/8" Diameter ) going through one of the holes to the other side of bracket with snap rings on each end to hold it in.

here is a diagram, it is number 52

http://www.boats.net/parts/search/BR...ION/parts.html

I am no expert for sure, but I would think that piece would only be needed on a motor with no power tilt/trim. Unless on your particular boat it is possible to tilt the motor down so far it would hit the boat.

That being said, on my 1972 25hp Evinrude, there is a spring on the one end that keeps that bar nice and snug in its place. Maybe you could find a spring that would work for yours if you need it.

I raised the engine 2 holes, took it out and it seems smoother and the wake is now clean and no spray, I heard a little loss of bite around a hard turn in the chop, but I was running it pretty hard, I think it should be fine for normal use, no issues with the temp. Now I will mess with a new prop. I maxed out @ 4500 RPM's with last years plugs and gas ( 1st trip of year ) 5 people 2 adults 3 kids and 40 gallons of gas. No GPS on boat so, no speed yet. The prop is all dinge up I filed it smooth but it's a mess 15 1/2 X 15
was reconditioned for more RPM last year. I have to start fresh. Any recomendations on prop size if I want to go to SS or stay with Alum ?

I had a 15 1/2 x 14 stainless prop on my 1985 Johnson 150. Would only turn a little under 5000 and get me 28mph. I always wanted to try a 14 1/2 x 17 as that is what everyone on here recommended. Never did because i was getting leery of the play in the steering shaft.