is a 76 merc. 115 inline 6 parts comparable w/86 mariner 90 inline 6???

Im looking to buy a 76 merc. 115 w/ a bad lower unit. I have a 86 90 w/ a good low end. Will these parts interchange. What other parts if any will I be able to use? From the picture of it, it looks very similar to my 86 motor. Let me know any info please. Thanks,
Nick

Re: is a 76 merc. 115 inline 6 parts comparable w/86 mariner 90 inline 6???

njrextreme said:

Im looking to buy a 76 merc. 115 w/ a bad lower unit. I have a 86 90 w/ a good low end. Will these parts interchange. What other parts if any will I be able to use? From the picture of it, it looks very similar to my 86 motor. Let me know any info please. Thanks,
Nick

Click to expand...

I think I may have found my answer. Can anyone verify for me?

ALL inline 6 powerheads produced between 1973 and 1988 ( + the 1972 140hp ) can be bolted to same midsection...

ALL DC engines uses the same crankshaft ( 90 > 155 hp)
Are 2 different styles of rods used, just use 6 rods of the same style and you will be fine.

Pistons...
HIGHdome power port pistons ( 150 and 155 hp + some 140hp engine ( 78 > ).
HIGHdome NON powerport pistons ( early 140hp, early 115hp + later 90hp engines )
LOWdome powerport pistons ( later 140hp engines + later 115hp engines )
Powerport pistons can be used in ALL engines, just use 6 indentical.
NON powerport piston CAN'T be used inn a power ported block .

Reedblocks.... basically 3 types
10/10 non banjo reeds ( old 140hp + old 115 + late 90 hp engines )
10/10 banjo reed ( 150hp, later140 hp + the 155hp models ( XS )
10/8 blocks.... used on the later 115hp ( 83 > 88 )
Are some minor other difference too so don't mix/match without knowing the risk

Carburetors.... to many types , just don't mess around here without knowing the risks....






Quote:
Originally Posted by mcsmonkeyshine
from what I understand from one of the mechanics i had working on my 90 the 115 is the same as a 90. I do not know for sure

The newer ( 1983 > ) are the same as the pre 83 115 hp

New 90 are rated at the propeller .
Old 115 are rated at the crankshaft .


Arne Kjetil

Re: is a 76 merc. 115 inline 6 parts comparable w/86 mariner 90 inline 6???

You can bolt that later-style lower unit right up to the ol' 115 and it'll be quite an improvement over the 115's original lower unit.

The older 115 will probably have a distributor-fired ign which is not the same as the later model 90 hp. The blocks have the same mounting bolt pattern, although there are differences due to the ignitions and this would make it more difficult to swap them out. Crankshafts will interchange, and the pistons/rods will physically swap although the later ones will likely be of different (improved) design.

If your 90hp has power trim 'n tilt, a nice mod would be to bolt the 115 upper end (powerhead, cowlings and all) on the newer center. The integrated PT'nT is a much cleaner installation than the old 2-ram setup with external pump.

HTH.........ed

Re: is a 76 merc. 115 inline 6 parts comparable w/86 mariner 90 inline 6???

emckelvy said:

You can bolt that later-style lower unit right up to the ol' 115 and it'll be quite an improvement over the 115's original lower unit.

The older 115 will probably have a distributor-fired ign which is not the same as the later model 90 hp. The blocks have the same mounting bolt pattern, although there are differences due to the ignitions and this would make it more difficult to swap them out. Crankshafts will interchange, and the pistons/rods will physically swap although the later ones will likely be of different (improved) design.

If your 90hp has power trim 'n tilt, a nice mod would be to bolt the 115 upper end (powerhead, cowlings and all) on the newer center. The integrated PT'nT is a much cleaner installation than the old 2-ram setup with external pump.

HTH.........ed

Click to expand...

Thanks. I didnt want to buy this thing and not be able to use it. My lower unit has tilt trim but the ram needs a seal. The force of the motor pushes it down in the water. I plan on putting the complete top on my bottom. Thanks again for the help.