MC-1 Upper on Alpha-I lower?

[L8-Again]

My neighbor knows I have done LOTS of my own repairs.....but I am NO expert and the only reason my old boat is running as well as it does is because of the information I have found on this site.

At the lake a few weeks ago his engine quit hard while accelerating. Engine would not crank. Removed drive, engine cranks. Pulled drive cap and saw a couple of broken teeth. Oil drained out clean, no metal or water, upper seized.

His is a 1985 Alpha and I have a 1979 MC-1, same gear ratio numbers stamped in the uppers, 1.65, both v-8 chevy powered 260's. His actually may be an R or MR but I did not check the serial numbers. I will call it an Alpha for now.

I was thinking about selling my extra upper to him (cheap) but I am wondering if it will actually work. When I replaced my outdrive I used SEI upper and lower complete even though the upper was just fine. The lower was damaged in the driveway by the previous owner, forgot to raise it to move the trailer.

I can see a few obvious differences in the two: cap has lifting hole, ribs on the side, the anti-cavitation plate is much smaller on the MC-1, smaller rear trim cylinder mounts--less metal but same sized hole; but there may be other differences I cannot see or do not know about.

I was thinking that there might be a problem with the Alpha lower main shaft not having a grove below the splines for an o-ring or the pre-load pin in the end of the shaft. Haven't split the Alpha apart yet.

Basically, if it works then we can put it back together tomorrow and be on the lake. If it doesn't, then I'll have him order an SEI and we can bolt it up and go to the lake in a week or so!

Has anyone successfully done a 'marriage' like this and been successful?

L8-Again

 

[Eric 3.7LX Alpha 1]

Re: MC-1 Upper on Alpha-I lower?

The preload pin is not a problem. The Alpha one will bolt up to it and it will work.

 

[Bondo]

Re: MC-1 Upper on Alpha-I lower?

My neighbor knows I have done LOTS of my own repairs.....but I am NO expert and the only reason my old boat is running as well as it does is because of the information I have found on this site.

At the lake a few weeks ago his engine quit hard while accelerating. Engine would not crank. Removed drive, engine cranks. Pulled drive cap and saw a couple of broken teeth. Oil drained out clean, no metal or water, upper seized.

His is a 1985 Alpha and I have a 1979 MC-1, same gear ratio numbers stamped in the uppers, 1.65, both v-8 chevy powered 260's. His actually may be an R or MR but I did not check the serial numbers. I will call it an Alpha for now.

I was thinking about selling my extra upper to him (cheap) but I am wondering if it will actually work. When I replaced my outdrive I used SEI upper and lower complete even though the upper was just fine. The lower was damaged in the driveway by the previous owner, forgot to raise it to move the trailer.

I can see a few obvious differences in the two: cap has lifting hole, ribs on the side, the anti-cavitation plate is much smaller on the MC-1, smaller rear trim cylinder mounts--less metal but same sized hole; but there may be other differences I cannot see or do not know about.

I was thinking that there might be a problem with the Alpha lower main shaft not having a grove below the splines for an o-ring or the pre-load pin in the end of the shaft. Haven't split the Alpha apart yet.

Basically, if it works then we can put it back together tomorrow and be on the lake. If it doesn't, then I'll have him order an SEI and we can bolt it up and go to the lake in a week or so!

Has anyone successfully done a 'marriage' like this and been successful?

L8-Again

Ayuh,.... It'll work, just fine...

 

[ktbarrentine]

Re: MC-1 Upper on Alpha-I lower?

My neighbor knows I have done LOTS of my own repairs.....but I am NO expert and the only reason my old boat is running as well as it does is because of the information I have found on this site.

At the lake a few weeks ago his engine quit hard while accelerating. Engine would not crank. Removed drive, engine cranks. Pulled drive cap and saw a couple of broken teeth. Oil drained out clean, no metal or water, upper seized.

His is a 1985 Alpha and I have a 1979 MC-1, same gear ratio numbers stamped in the uppers, 1.65, both v-8 chevy powered 260's. His actually may be an R or MR but I did not check the serial numbers. I will call it an Alpha for now.

I was thinking about selling my extra upper to him (cheap) but I am wondering if it will actually work. When I replaced my outdrive I used SEI upper and lower complete even though the upper was just fine. The lower was damaged in the driveway by the previous owner, forgot to raise it to move the trailer.

I can see a few obvious differences in the two: cap has lifting hole, ribs on the side, the anti-cavitation plate is much smaller on the MC-1, smaller rear trim cylinder mounts--less metal but same sized hole; but there may be other differences I cannot see or do not know about.

I was thinking that there might be a problem with the Alpha lower main shaft not having a grove below the splines for an o-ring or the pre-load pin in the end of the shaft. Haven't split the Alpha apart yet.

Basically, if it works then we can put it back together tomorrow and be on the lake. If it doesn't, then I'll have him order an SEI and we can bolt it up and go to the lake in a week or so!

Has anyone successfully done a 'marriage' like this and been successful?

L8-Again

Both of those drives will have the o-ring groove on the vertical shaft (if the 85 alpha has not had a later lower put on). In fact, you don't need (and shouldnt install) the o-ring on the vertical shaft when putting the upper and lower back together. It generally causes more problems than it addresses. Thats why merc did away with the O-ring groove on later alphas. (the o-ring interferes with the shaft seal in the upper. most times gets hung up causing problems with reassembly, and sometimes the o-ring gets lodged in the shaft seal, allowing water to get into the vert shaft splines.)

 

[achris]

Re: MC-1 Upper on Alpha-I lower?

His is a 1985 Alpha and I have a 1979 MC-1, same gear ratio numbers stamped in the uppers, 1.65, both v-8 chevy powered 260's. His actually may be an R or MR but I did not check the serial numbers. I will call it an Alpha for now.

Hmmm.. Something not quite gelling here.. The 350 (5.7) '260hp' V8s never came with 1.65:1... Only 1.5:1.. Me thinks something has already been changed....

 

[L8-Again]

Re: MC-1 Upper on Alpha-I lower?

Thanks for all help! Will get a new impeller, some gaskets and oil and git'r'done!

achris:
I remember wondering about that myself a few years ago. I think I remember reading somewhere that the gear ratio was due to the altitude I am at. My boat was manufactured and sold in the Salt Lake City area, 4000+ feet in elevation, and the dealer may have changed the upper prior to sale. I dunno...but the numbers stamped into both uppers are clearly 1.65 and both our boats were purchased new from dealerships in Utah in 1979 and 1985.

Thanks again for all the replies and help.

 

[achris]

Re: MC-1 Upper on Alpha-I lower?

Thanks for all help! Will get a new impeller, some gaskets and oil and git'r'done!

achris:
I remember wondering about that myself a few years ago. I think I remember reading somewhere that the gear ratio was due to the altitude I am at. My boat was manufactured and sold in the Salt Lake City area, 4000+ feet in elevation, and the dealer may have changed the upper prior to sale. I dunno...but the numbers stamped into both uppers are clearly 1.65 and both our boats were purchased new from dealerships in Utah in 1979 and 1985.

Thanks again for all the replies and help.

That'd explain it....
Thanks for clearing it up...

 

[mercs4mark]

Re: MC-1 Upper on Alpha-I lower?

correct me here if i'm wrong but from my understanding this gentleman wants to put a mc-1 upper from his 1979 to a 1985 alpha bell housing and use the alpha lower..... this will work but won't he have to change the input shaft from the mc-1 8 inch to the alphas 9 1/2 inch

 

[Bondo]

Re: MC-1 Upper on Alpha-I lower?

correct me here if i'm wrong but from my understanding this gentleman wants to put a mc-1 upper from his 1979 to a 1985 alpha bell housing and use the alpha lower..... this will work but won't he have to change the input shaft from the mc-1 8 inch to the alphas 9 1/2 inch

Ayuh,.... The only MC-1s with the shorter shaft are those for an In-line GM motors,....

All other MC-1s, use the 9" shaft...

 

[ShowMeGuy]

Re: MC-1 Upper on Alpha-I lower?

Ayuh,.... The only MC-1s with the shorter shaft are those for an In-line GM motor,....

All other MC-1s, use the 9" shaft...

Nice to know.. didn't now that.