Fitting post '78 OMC V4 transom bracket to '75 model motor

[Gilera]

Hi. I have been tossing up buying a 1975 Johnson 115 but it may have a problem with the trim module. I've been given some great advice from this forum which pointed out that these modules can be difficult to work on and to get parts for. I have also been told that the difference in design of the transom bracket compared to later models would make it hard to retro fit a later trim module. What about replacing the whole mounting bracket from a later motor? Is this a simple procedure? I have just seen a mounting bracket from a later model Evinrude V4 advertised. See photos attached. Would this work?

[Gilera]

Motor I'm looking at.

[powerabout]

Its a bigger project than you think, the swivel bracket needs changing and to do that it needs machining to fit the old engine, there was a thread on the conversion here somewhere.

[Gilera]

Thanks, that answers my question perfectly.

[Paul Vaillancourt]

I have done it, it didn't require any machining to the clamp bracked, but you need bushings to make up the difference in the steering shaft size. This thread should help you out. I was able to buy the bottom bushing "off the shelf" and the upper one i had made from Delron.
https://www.screamandfly.com/showthr...11#post2926011

[Gilera]

The bracket I was looking at has sold. I just rang an outboard wrecker and they said $880 for the bracket + working trim and tilt from an 80s model! The guy told me that thr trim and tilt is the most valuable part of the old motors. No thanks. I could get a complete parts engine e.g. an 80's model 115 or 140 with seized powerhead but working tnt for about $400 in pretty ordinary overall condition. Then I have to sort the bushings.

If the powerhead on these '75 models has a different bolt pattern and the bracket is different then I'm guessing there would be limited parts that would be compatible from a later model. What about the lower unit - are they also different? Carbs? Any other useful upgrades that will fit?

[Paul Vaillancourt]

Yes the lower unit is different also, it has the same bolt pattern but the way it shifts is different and i believe the gear ratio is slightly different. You may be able to use the newer lower unit (as long as its not newer than 1992 or 1993 when the drive shaft got longer) if you change the intake manifold so the linkage for the shifter will work. I never tried that and cannot guarantee that the intake will bolt up to the older style block.
I was able to put the carbs from a 1978 140 (1 3/8") on the 1973 135 but I never got the electric choke to work with them and its been so long since I did it I cannot remember what the problem was.