Question for the Merc guy's

[OleRed]

Someone drug up this old Merc today, but it's got the wrong look to the lower unit, speedo pick up in the case, and the wrong look for a 1979 model as it is titled, but the ser # 5169608match the title.

Obviously the lower unit is a later model,  any problems with that,  I have a changed a lower unit once that I had to remove the alighnment pins to use it, and it worked alright, but it didn't look like this one.   Any Opinions, is this a Rich question ?

[Rich_V174SS]

Looks like any other Merc 115 lower unit that I've seen. If it's got the same gearing ( I think 2:1 ) and the shaft splines into the power head are correct I don't see why you couldn't use it. My own 1983 115 has a speedo pickup built into it. What doesn't look right to you?

[OleRed]

Hi Rich .. I haven't worked on the outboards in Years, and the one's I did were in the 50's and 60's, only occasionally did I twist bolts on the 70's, but this lower unit just don't seem to fit the 70's era to me .. but, what do I know ?
It came on a package I bought for the trailer, he said it has good compression, suposed to be a runner but he never got it wired up to the boat, so, who knows.

I think I have a plan for it if it seems to be a good motor ... we'll see ?

[Hyperacme]

It looks like what you said a latter model gear case.
Newer design but fits older motors.
Not sure when Merc changed.
Would guess mid to late 80's.

[frosty]

Hi Red, it looks the same as my 79 115 merc. As far as I know mine is the origional gearcase.  Decals are a little more fadded than mine.  Good old motors.

[Rich_V174SS]

Red, the hole you speak of where the speedo hose comes through is actually part of the leg, not the lower gearcase. I don't think mine has that "hole" quite like that but mine does have the speedo pickup and hose and it is the original gearcase for my '83 115. If others who have the same vintage engine also have the angled trailing edges on the gearcase then perhaps it must be correct. I don't recall seeing any that were straight. I do know that Mercruiser Alpha One's and earlier were straight and the Alpha One Gen 2 drives were angled.

[badgercarlson]

Here's what my 1977 1150 looks like.  The snow on the mat is from the 12 inches of wet heavy snow I just cleaned up.  Thank god for snowblowers !!!!!

[V153]

Not by any means a Merc expert but my untrained eye tells me the change happened somewhere between 77 & 79 ...?

Guess I'm gonna have to start doing some 'whittling' on mine. Wonder how far I can go? Design makes sense to me. Looks like it'd focus more water toward the prop ...?

[MarkS]

My 63 Merc 1000 has a newer style gearcase on it I'm told, I believe one of the guys said it was a 79 or newer;

The lower unit dates from '79 or newer and will have a stainless steel driveshaft, definitely a plus.

It does take some skill and ingenuity to adapt a later lower unit to the older-style motor; you have to shorten the shift shaft (or swap new for old), and modifiy the reverse lockout cams & plastic spacer. Otherwise the reverse latch mechanism won't work right.

The last issue you'd see with this setup is that the newer driveshaft won't have an O-ring groove to seal the crank/driveshaft splines. If you plan on keeping this motor and leaving the later-style lower unit, it'd be best to grind an O-ring groove. This'll keep the splines from seizing or rotting away.

[OleRed]

Here's what my 1977 1150 looks like. 

Thats what I was remembering it to look like, rounded cavitation plate, strait trailing edges .. just didn't know if and when they changed things up,  Thanks guy's .. I found a place for it  ..