Motor mount bolting pattern compatibility?

[ShoestringMariner]

I’m planning both a transom rebuild AND a re-power.
Im concerned with remounting my original motor (Merc 650), followed shortly with a swap to a 70hp OMC. Both are mid 70’s.

Does anyone know if Merc and OMC have a similar mounting pattern? Or will I have to seal and fill and re-drill new holes?

thanks in advance

 

[Scott Danforth]

the patterns became universal in the mid 80's so you will be drilling new holes

 

[GA_Boater]

Why not put the OMC on and avoid the hassle?

 

[ShoestringMariner]

ThisThanks guys. I was hoping to fit in the new transom before fishing season opener and re-hang the merc until the OMC is ready. The transom is soft and makes me nervous but I used it successfully all last year, so I may just wait until summer when the fishing gets tough.
And I guess this way I can do a wet test when selling the Merc. should the buyer want to try it

 

[jimmbo]

If the transom is soft, and flexing, it is weakening either the Aluminum skin, or in the case of Fiberglass, breaking the threads of glass that make up the Mat, Cloth, Rowing.

 

[ShoestringMariner]

If the transom is soft, and flexing, it is weakening either the Aluminum skin, or in the case of Fiberglass, breaking the threads of glass that make up the Mat, Cloth, Rowing.

Well that’s definitely a little concerning and very good to know. Aluminum boat, which I’m a lot more confident in than fibreglass
Unfortunately I won’t have enough time to get it completed at this point. So I have to weigh out taking my chances or missing the opener.