How many holes in your transom

bobsquatch

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When I recently bought a 1970 Chrysler commando 15 foot center console boat. It had a 1990 Johnson 88 hp on it which I just swapped out for a 1973 Johnson 115. My question is this, the 88 only had the top two mounting holes drilled through the transom albeit also through a metal plate capping the transfom. The bottom portion of the mounting bracket where you would put the bottom two bolts is well below the waterline which is why I assume nobody ever drilled it out. It would be very easy for me to use the mounted engine as a template and drill two more holes for the lower portion of the motor mount and then just be very very diligent about waterproofing. What would any of you recommend
 

bobsquatch

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I don't really see the need unless you hit the bottom with your propeller the load on it should be minimal as long as you don't get throttle happy when reversing.
 

Chris1956

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The lower transom thru bolts are essential to keeping the motor attached to the transom. If you hit something with the gearcase, the resulting leverage will pop the motor off the transom if she had only thumbscrews holding her to the transom, or could easily break the transom bracket if thrubolted on the top only.
 

smokeonthewater

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ummmmm YES drill the holes..... would be foolish to leave out half of the mounting bolts.... My Wellcraft has probably 40 or so holes below the water line.... all sealed with 5200 and no issues... many are original and still sealed from 1989....
 

gm280

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I agree with Chris1956 on his assessment as well. If it were my boat, I wouldn't even hesitate to drill the bottom holes to secure the engine. BUT if it were mine, I would also check out the total transom to verify no rot or any other issues before drilling the new hole. And then I would remove the engine, or lift it up after marking the new hole locations and then drill way way larger holes then the actual size needed and use some polyester resin and fiberglass fill material and fill them back in again. Then once those holes were cured, I'd drill the exact size holes in that polyester resin so it was totally water proofed with no possibility of water intrusion to the transom. But that is just me and how I'd do it. Everybody has their own ways and I'm sure others will comment on their suggestion. But either way you go, I honestly would not go out in that setup without the extra bolts through the transom to secure the engine. You are talking about a lot of torque there and merely two thumb screws are not even enough! JMHO!
 

bobsquatch

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No problem it just was like that through bolted through a top plate in the top of the transom like I said the only issue would be if you struck something in the water and who knows if that will ever happen so I guess it is best to be prepared I will drill the bottom ones so should I go to the very bottom of the motor bracket there are several holes. Having through bolts through the very top set of holes in the very bottom set of holes seems to be the most secure Way to go but there are options. I have a brand-new tube at 5200 and stainless steel bolts that came with the other motor and backing plates to distribute the load.
 

smokeonthewater

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Don't go to the very bottom UNLESS your top bolts are at the very bottom of their range.

The bracket it designed to be adjustable.... IE if the top bolts are 2" from their highest position so should the bottom bolts be.

More precisely THIS is the correct bolt pattern.

273833d1349888037-engine-mounting-bolt-pattern-e-tec_40hp_boat_transom.jpg
 

gm280

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If you drill the very bottom hole out, you will secure the engine, but then you have no option if you need to raise the engine for a better control. I'd go the center if I were doing it, or even the top hole. Then you have the option to raise it if needed. That is if you are presently sitting down flat on the top of the transom now. If the engine is presently raise up a little off the top of the transom, then don't go to the top hole but down a hole or two... But that is just my opinion...
 

smokeonthewater

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FWIW when I bought my V-20 it had the above bolt pattern but I mounted a '75 merc 115 on it so I filled the holed and drilled new ones.... NOW I'm on the lookout for a newer engine so I'll likely get to fill my new holes and REdrill the original holes... LOL
 

bobsquatch

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That's funny Kevin Murphy's Law. Since the existing boots are in the absolute top hole set for the upper bolts I will also drill for the upper bolt holes for the lower bolts preserving the design intended adjustability of the bracket
 

gm280

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Sound like a plan to me. That way IF you have a need to raise the motor, you simply remove the bolts and lift the engine and reinstall them again in the lower holes on the brackets...
 

Frank Acampora

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Very Few guys beside me will preventively plate a transom and very few will do it correctly. A 1970 Chrysler boat with a plate reinforcement is VERY LIKELY to have a soft or punky, weak transom. With only the two top bolts, if you take a hard hit, it is a likely bet that the plate will bend and the transom will break.
Therefore, DEFINITELY drill and bolt the bottom of the clamps. However. Test the transom for soundness too. If it is soft or partially rotten it can be repaired using a product called Git-Rot. A bigger job would be to replace the transom but only if you wanted to keep the boat for sentimental reasons.

And BTW: Get rid of the OMC and find an old late 70s Chrysler 75, 85, or 90 to hang on the hull. That's my story and I'm sticking to it!

Go to "The Chrysler Crew" for photos and enthusiasts.
 
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bobsquatch

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I have not been able to locate any soft spots through sounding so the transom appears to be in decent shape I however have not pulled the plate off I will drill the bottom holes and I would love to put it in original Chrysler motor on my Chrysler boat but it's just an old beater and I am not going to sink a ton of money into it. That being said man does this thing rides like a cloud it has a super deep draft but it is cushy.
 

Frank Acampora

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Bob: You need not spend a lot of money! Old Chrysler engines in running condition will usually sell for a couple of hundred bucks. You simply need to search for them.

Chrysler bought West Bend outboards in the early 1960s. They were looking to vertically integrate and bought Lone Star boats. They designed several new hulls and started manufacturing in Plano, Texas. These were well designed and quality hulls.These hulls were generally foam filled which made them more solid and rigid and gave them a softer ride. The only drawback was that sometimes the foam would get waterlogged which increased weight and negatively affected performance.

Again, go to The Chrysler Crew. You can find all this info and more (such as engines for sale)at this Chrysler owners site.
 
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V153

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Apr 16, 2011
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A lil late I spose, but here's some mounting stuff:
 

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bobsquatch

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Thanks everybody. Frank as time goes on and the boat proves worthy I may very well restore it with the correct engine. I love that kind of thing too. But for the time being I am just making her sea worthy and testing comfort and capacity for fishing and fun.
 

bobsquatch

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Also Frank I have got most of my info from chryslercrew.com and also allpar.com. Great sites.
 

bobsquatch

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Well after looking at the mounting bracket again the bottom holes are slots so I will drill out for the top of the slot the second question I have is with the plate being on the top of the transom it's about an 1/8 inch thicker them where the bottom the transom I was just going to use stainless steel washers of the same thickness what do you think?
 
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