'61 75hp to '63 75hp

[yorab]

I am rebuilding my 1963 75hp #75383 Selectric as my winter project. I realize that there is still much boating to be done this season, even in PA, but the new school semester has begun, so my summer is basically over. Anyway, I found that my pistons are pretty much shot. I can see some scoring on the cylinder walls as well. I do have a spare parts motor that I bought a few years back, but it is a 1961 75hp #50927 without electric shift. Will the powerhead components interchange between these two motors? Will the complete powerhead bolt up properly between the two?

 

[F_R]

Re: '61 75hp to '63 75hp

There are many differences between those two. The biggest would be the alternator and ignition systems. Whether you can transfer the stuff over to a '61 powerhead would take a bit of research with the parts catalogs.

 

[yorab]

Re: '61 75hp to '63 75hp

Should I just get a parts catalog for the 61 and simply look at the part numbers to see if they match the 63? I am mainly concerned with the pistons and block.

 

[F_R]

Re: '61 75hp to '63 75hp

I just checked for you. The pistons and cylinder blocks are the same.

 

[tashasdaddy]

Re: '61 75hp to '63 75hp

with the scarity of elect lower parts, i'd be tempted to use the mechanical lower if possible.

 

[yorab]

Re: '61 75hp to '63 75hp

Thanks guys. I've just disassembled the powerhead from the 61. The block and pistons are indeed the same. The 61 powerhead and components are in much better shape than the 63 so I think I'll use them. I shouldn't need to oversize the bores or pistons like I probably would have with the 63 block. I'll let my local shop guy take a look. I did notice that the connecting rods are much heavier in the 63. The casting numbers are: 61-307214; 63-308261. I think that I will use the heavier rods for the rebuild. I would imagine that the engineers changed to the heavier rods for a reason.
As far as the lower end, I will consider using the mechanical. I know nothing about the mech. shifting so I'll have to do some research on the forum. I know that I need the linkage from the motor to the control box. I would imagine that I would need to get another control box as well. But first I need to inspect the mech. unit to see if it is fit for use.