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ContinuousWave: Whaler Performance
Intial setback plate height on Montauk?
|Author||Topic: Intial setback plate height on Montauk?|
posted 04-22-2002 03:38 PM ET (US)
I installed a CMC setback plate (ML-65) this weekend on my 1989 Montauk (90 HP V4 Evinrude). Can anyone suggest a good starting point for proper engine height? Currently, the plate is adjusted so that the cavitation plate is about 1 1/2" above bottom of the transom.
BTW, before installation of the plate:
40 mph @ 5200 rpm (light load)
Can I hit 45 mph?
Thanks in advance,
posted 04-22-2002 04:59 PM ET (US)
That's about as high as you'd want to go. Even at that height, you should be running a "surfacing" performance prop, like an OMC Raker or Mercury Laser, or one of the aftermarket brands like a Stilleto.
posted 04-22-2002 10:42 PM ET (US)
Larry... should I start at a lower setting and work my way up?
The prop is a OMC Rapture...
posted 04-22-2002 11:27 PM ET (US)
"Rapture" is a tradename used by Michigan Wheel, not OMC, but it is a performance prop and should be fine. Start at about 3/4" high, and move it up until you get excess slippage. Just be careful you don't pull the water intake openings above the water flow, or you'll start drawing in air and burn the top pistons. 2 1/2" is about max for most engines and props without high performance water intakes. You can easily measure this distance on your engine.
There are a lot guys on this site who have had experience with your situation.
posted 04-23-2002 10:46 AM ET (US)
If already mounted...try it. I have mine about 3" up.
posted 04-23-2002 01:10 PM ET (US)
I have a CMC with a 90 Yamaha mounted on the top engine hole and the jack plate is about 3" up. I may have a 1/2" of travel left and may go up, because I have not blown out at the 3" mark yet. Wheel wash at normal cruise trim is just starting to look about right.
posted 04-23-2002 02:49 PM ET (US)
If anyone is interested.... here are some pictures of the installation:
posted 04-23-2002 03:30 PM ET (US)
Jack that thing up. I would have started with it up higher on the plate....but too late now. You can go about another 2".
posted 04-23-2002 03:32 PM ET (US)
I have the same jack plate and started out with the engine about the same hight you have in the pictures. Like I mentioned in above post there is only about 1/2" left of travel and the prop has not blown out yet.
posted 04-24-2002 04:36 PM ET (US)
When I had the new 90 put on my montauk, the mechanic mounted it two holes up to avoid the problem with the lower bolt hole in the well.
To check height I set the motor level while on the trailer and sighted down the cavitation plate to make a mark on the hull with a pencil. I then measured this mark up from the bottom of the boat. It is almost exactly 1.5". The motor gets plenty of water at this height but I think if I had it any higher it wouldn't. I can only use a moderate amount of trim without breaking the prop lose.
posted 04-26-2002 07:00 PM ET (US)
I tried out the new jackplate setup this afternoon. Ended up about 2-1/2" above the bottom of transom.
All data by GPS and light load:
Not bad for a 13 year old Envinrude 90Hp V4.
posted 09-29-2002 11:50 AM ET (US)
I am thinking about putting a stetback plate on my supersport. I have a Yamaha 4s which is heavier than your application. How much lower did the transom drop compared with no setback plate?
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