Allison Hydrofoil Installation

[Hunter]

Tomorrow, I’m installing an Allison hydrofoil on my 225 Pro Max. If the SM gearcase was a lot cheaper I wouldn’t humble myself to this but the thing didn’t come with any instructions so before I start drilling holes....

Does anyone have any advise/techniques regarding installation?

Hunter

[Way2Fast]

I recently installed the hydrofoil on my SM. It is an easy job. I first clamped it to the bottom of the gearcase plate and drilled the attachment holes in the SM cavitation plate from the bottom up. It did not fit properly as the gearcase plate has a radius while the hydrofoil is straight. this can be overcome in one of two ways. (1) use rubber faucet washers between the plates at each of the screw holes. or (2) put a light film of grease on the top of the hydrofoil and also on the bottom of the gearcase plate. then apply silicone sealer to the top of the hydrofoil (only that part that contacts the gearcase cavitation plate) Now tighten the screws. the excess silicon will squeeze out and the plates will fit perfectly. The grease provides for easy removal in the future. I used the silicone method on mine and the installation is flawless.
Richard

[Hunter]

Thanks for the response. I hadn't considered filling the gap with silicone. I'm heading to the garage now.

By the way, what boat/engine are you running?

What changes did you see after installation?

[Delta]

Hunter:
I had the same question with mine.
I called the Bakers,and they told me it was designed to be tightened up against the radius...to be bent.No silicone.No rubber washers.
I haven't had a chance to install mine yet,so I can't give you any feedback there.
Good luck,Delta

[Hunter]

Well, I bolted the thing on. It went pretty well with all the holes aligned and straight despite the crushing 102 degree temperature in Enid, Ok that forced me to drink three Molson Ices before mission complete. I left out the silicone for now. I'm going to run it for a few hours, then pull it off for an inspection and then probably re-install it with silicone and cut the excess bolt off with a dremel. Or perhaps I should get a life....

[Way2Fast]

Hunter; I'm running a STV River Rocket center steer with a 2001 Drag on it. You will probably notice more of a change getting on plane with a v bottom than I did with the STV. Either way it jumps on plane without having to touch the trim. Don't over tighten the Allison hydrofoil bolts. I've heard that the alum is soft and the countersunk holes will enlarge easily. The silicon doesn't prevent the foil from taking the shape of the gearcase cav. plate. It only makes the installation a lot neater.

[Delta]

Way2Fast:
That's a good idea!
The silicone will help distribute the force on the bolts/plate.
Thanks,Delta

[Gordie Miller]

Guys, come on, quit kidding yourselves. The silicone will not spread the load of anything. These are only #10 bolts that hold this thing on, just drill the holes, put in the bolts and snug them down. If you want to be real trick though, you can remove the anode, take it to a local machine shop and have it milled to match the bottom of the cavitation plate. This thing is not NASA designed and wind tunnel tested, you're over engineering the hell out of a very simple, straight forward installation.

[Hunter]

Overengineering? Well that's half the fun!

So I just got off the lake and, between plugging the vents on my 26 Trophy Plus and the Allison, the bowrise is half what it used to be and the holeshot is much more impressive.

The black substance covering it has begun to shed though. Does it serve the same purpose as the plastic wrap on raw hamburger packages?

[Way2Fast]

Don't underestimate the strength of silicone sealer. It holds together the glass panes on my 125 gallon fish tank. What does fresh water weigh...6 lbs a gallon?? that is a LOT of weight and pressure. I also remember one time when a friend tried to remove a 235 Johnson from his transom. He had put silicone on before bolting it. Guess what...the silicone held the motor on even after the bolts were removed It took 2 guys to pry it off!! That is why I suggested to put grease on the hydrofoil and cavitation plate....otherwise you would never be able to remove it without destroying something.

[Ranger976]

Well, I bolted the thing on. It went pretty well with all the holes aligned and straight despite the crushing 102 degree temperature in Enid, Ok that forced me to drink three Molson Ices before mission complete. I left out the silicone for now. I'm going to run it for a few hours, then pull it off for an inspection and then probably re-install it with silicone and cut the excess bolt off with a dremel. Or perhaps I should get a life....

Drinkes a good beer....up north here by the border they even taste better....Jim

[Ranger976]

Well, I bolted the thing on. It went pretty well with all the holes aligned and straight despite the crushing 102 degree temperature in Enid, Ok that forced me to drink three Molson Ices before mission complete. I left out the silicone for now. I'm going to run it for a few hours, then pull it off for an inspection and then probably re-install it with silicone and cut the excess bolt off with a dremel. Or perhaps I should get a life....

Drinkes a good beer....:cheers: :cheers::cheers: up north here by the border they even taste better....Jim