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Filling blindholes / raising motor
RogueII
#1 Print Post
Posted on 09/30/14 - 10:55 AM
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I am planning to raise my 1987 Johnson 90 all the way up, glassing in the blind holes and re-drilling new holes per the recommendations to accommodate an E-Tec when I ultimately repower and to improve performance with the current engine until that time.

Does anyone have pictures of this process? I am not near the boat and am trying to evaluate my options. Right now I am thinking I can remove the old motor bolts, elevate the lower unit and tie the motor out of the way via my barn's ceiling beams while I fill the blind holes with 3/8" mahogany plugs and west system epoxy.

From there I can reinstall the top bolts "all the way up" and drill new bottom bolts from the outside transom in. I will then coat the lower bolt holts with thinned epoxy, let cure and bolt with 4200.

PS. My lower engine bracket has the "slot" arrangement rather than "holes" -- I believe this is the case with the Etec as well correct? I don't want to drill the new bottom holes in such a way that they don't perfectly match the future engine however if they both use the slot approach this is irrelevant.

(corrected the abbreviated year as per guidelines on front page)


Edited by Joe Kriz on 09/30/14 - 11:20 AM
 
Joe Kriz
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Posted on 09/30/14 - 11:21 AM
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What boat are you doing this on?
http://www.whalercentral.com/articles...icle_id=82

Lots of photos on this.
Look in the Project Albums and the Personal Pages.

Here's one:
http://www.whalercentral.com/userphot...lbum_id=64


Edited by Joe Kriz on 09/30/14 - 11:22 AM
 
RogueII
#3 Print Post
Posted on 09/30/14 - 11:28 AM
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1987 17' Montauk. Thanks Joe I will have a look.

 
Joe Kriz
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Posted on 09/30/14 - 11:39 AM
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OK. 1987 Montauk.
You may have the full depth splashwell and can drill the red holes.
You need to measure to make sure.

Look at this members personal page who has a 1987 hull.
Look at the 6th photo down.
http://www.whalercentral.com/infusion...r_id=29977

You really want to drill the red hole if possible.
If not, then the yellow, or if someone's hull is much older, then the green hole.

As always, measure twice and layout the lower hole on the inside and the outside of the transom before drilling. Make sure the hole clears the bottom of the splashwell including the washer.

 
RogueII
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Posted on 09/30/14 - 11:48 AM
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Thanks Joe I will shoot for the yellow holes.

Am I missing something in that diagram or are the new lower holes each 1.5" in from the top holes on either side?

I see that they are 7.25" down from the top holes.

Thanks.


Edited by RogueII on 09/30/14 - 11:49 AM
 
Joe Kriz
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Posted on 09/30/14 - 12:08 PM
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The Green holes are 1/2 inch lower then the black blind holes which makes the green holes 6 1/2 inches below the top holes.

The upper holes in the bracket are all 3/4 of an inch apart as are the bottom holes in the drawing.
6 1/2, 7 1/4, 8 inches down from the top hole in the transom.

We are interested to see which holes you need to drill.

 
RogueII
#7 Print Post
Posted on 09/30/14 - 12:12 PM
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I will likely be performing this mod in late October; I will report back with my findings.

 
Weatherly
#8 Print Post
Posted on 10/01/14 - 6:23 AM
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The 1987 J90 Crossflow should only be mounted 1 hole up on a 1987 BW17 hull.

 
RogueII
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Posted on 10/01/14 - 7:06 AM
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Weatherly wrote:
The 1987 J90 Crossflow should only be mounted 1 hole up on a 1987 BW17 hull.


I have always found motors can be mounted higher than standard practice suggests. Mounted with the blind holes I can trim way up and still maintain enough prop in the water for full functionality.

What is your concern with mounting the engine all the way up?

 
Weatherly
#10 Print Post
Posted on 10/01/14 - 10:07 AM
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I experienced prop slippage in turns running three holes up on BW17 Custom with a 1987 J90 SPL (trim assist; not electric t/t) and a Stainless Viper 17 pitch (part no. 176623). I reset to 1 hole up and the cavplate was just above the waterline and the result was it ran better (no slippage) in the turns. I adjusted static trim bar to third hole out and also had higher speed but slower holeshot.



 
Finnegan
#11 Print Post
Posted on 10/05/14 - 9:09 PM
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Even though I am a Mercury guy, I have experience with OMC V-4's on a 17' hull, and I would say no more than 2 holes up (3rd hole in the pattern), and that provided you use a good holding prop like a Stiletto.

My Montauk originally came with an Evinrude V-4, and 1-1/2" up (3rd mounting hole) is all that was needed. Generally, the top set of hole CL's are 1-7/8" below top of transom, and the bottom set are 8" below those. The 1987 Montauk can accomodate the standard BIA pattern we are discussing.

Since engine bolts are 1/2", 1/2" pegs will be needed. If you are planning to finish gelcoat, do not use West Epoxy, since gelcoat will not bond to it for any period of time. Use Evercoat Formula 27 polyester resin paste.

Stick with exact BIA pattern dimensions for the lower bolts, since not all engines (like Mercs) have lower slots.

 
gchuba
#12 Print Post
Posted on 10/06/14 - 7:55 AM
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I have found that when drilling holes that require a precise lay out , I would use a template. I recently fabricated aluminum backing plate for the interior of the transom. I used a borrowed template from my boat mechanic. If I were drilling mounting holes in the transom I would fabricate the pattern onto a piece of 3/4" plywood and attach a lip on the top to let it hang from the top of the transom. I would also install some square blocks on the bottom of the holes (screwed in from boat side to give a bearing edge onto a drill bit on the outside). Clamp the template in place. The plywood thickness prevents the drill from wandering and if you use an elongated drill bit, the bit rests on the block for keeping it at 90 degrees and you can "eye ball" square from the top by looking down on the block as you drill. I have used this method often for structural bolt layouts. I found that even with pilot holes it is extremely difficult to maintain a tight bolt pattern freehand.

Garris

 
Whalerbob
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Posted on 10/07/14 - 5:22 AM
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Joe Kriz wrote:
You really want to drill the red hole if possible.


What's the advantage of drilling red vs Yellow? I'm planning this for my 1989 / 17' this winter and although I probably have room at the bottom to drill red I don't see any advantage to drilling so close to the bottom so I'm thinking yellow.

 
Joe Kriz
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Posted on 10/07/14 - 9:52 AM
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Bob,

That is the standard layout that most all hulls are drilled with today.

The upper black and the lower red holes is the "Standard" BIA layout.

The only reason we deviate from the Standard is because we don't have a choice in the older Classics.

 
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