115 e-tech Height Adjustment

I recently repowered my 17' Aquasport with a 115 e-tech. I'm wondering if the dealer installed the motor at the proper height on the transom. I thought there should be about 1/2 inch of water over the top of the ventilation plate when on plane. The current set up has about 3 inches of water over the vent plate. Any suggestions? I've looked for rigging instructions and dimensions but have had no luck. Any help would be appreciated.

Re: 115 e-tech Height Adjustment

I thought there should be about 1/2 inch of water over the top of the ventilation plate when on plane. WRONG!!

AV plate should be 1-2 inches above the keel of the boat. less foot in the water, less drag. as long as it is getting cooling water, and not ventilating, of cavitating. (blowing air) it is better.

Re: 115 e-tech Height Adjustment

The cavitation plate should be totally UNCOVERED @ WOT when you get the height right. 3" deep is nuts. Keep raising until you get there. If there's significant cavitation in tight turns, back down one hole.

Re: 115 e-tech Height Adjustment

Thanks for the input.

I tested my boat again today. It appears that the water goes up under the upper plate and completely covers the vent plate (see photo). My last motors' vent plate extended all the fwd to front on the lower unit. The geometry on the new unit might allow the water go up to the bottom of the upper plate. Water is definitley hitting the bolts on the bottom of the upper plate. Are you familiar with the vertical install requirements for the e-tech motors and/or the style lower unit? I included an attachment.

Also, I do not get anywhere near a good hole-shot with this new motor. My old 88 Special had better on-plane elapsed times. The prop I have is a Rapture 13 1/4 x 15. The WOT RPM's are good at 5600. The prop is ventilated. I wonder if plugging the vents would improve hole-shot performance? Once the prop hooks up, it accellerates very well.

Re: 115 e-tech Height Adjustment

Forget the deal with the red line ... the cavitation plate is the next one down (the big plate with the torque tab below it.) It should be uncovered @ WOT. BTW, I have two E-Tec 175's, and they are set so the top of the plate is fully uncovered @ WOT, but the motor make/type doesn't make any difference.

Also, if you have a water pressure gauge, keep an eye on it as you go up. If not, watch engine temperature.

Leave the two slotted openings alone and you need to be @ WOT, not just on plane.

Re: 115 e-tech Height Adjustment

I only have the idiot lights on the tach. Also, you can see on the photo that I only have about one bolt worth of up movement left before the lower slots bottom out. I'm taking the motor back to the dealer to fix some other rigging issues. I will not get a chance to check the vent plate at WOT before that. I will discuss the situation with them. Maybe they will agree to another check out ride to verify height adjustment. Boy, I'd to go along on that ride.

The other problem I have is poor hole-shot. My previous 90 hp Johnson got on plane a lot faster. I'm using the same prop, which is a 13 1/4 x 15 Mighigan Rapture. It is vented and cupped. I'm thinking the vents are causing the poor hole-shot. When the prop does bite, the boat accellerates great. The motor tops out at 5600 rpm. I would like to try plugging the vents with some solid grommets (or equivalent). Have you heard of anyone doing this (other than the Merc Variable Ventilation System)?

Re: 115 e-tech Height Adjustment

My 175's have terrific hole shot with BRP Rebel props. But that doesn't help you much. You're turning the right RPM's however. Maybe a prop change is in order', once you get the height right. Sounds like you really need to come up more.