1990 75hp Mariner upgrade?

[dfrants]

Does anyone know if it is easy to upgrade a 75hp Mariner into a 90hp? The guy selling this motor says its the same block.

 

[Chris1956]

Re: 1990 75hp Mariner upgrade?

it is probably the same displacement and number of cylinders, but diffferent porting, and perhaps other parts. Check out the part numbers for the two motors at the crowleymarine.com web site and see.

Normally a conversion of this type is too costly to be worthwhile.

 

[toyvette81]

Re: 1990 75hp Mariner upgrade?

alot of outboards are this way, such as some of the older 150 blackmaxs all you have to do is change the jets and timing module to make it a 200. im fairly certain that you can do this to a 75 also im thinking of doing it to mine right now.. just got to do some more reading.. everythings the same from a 75 to 90

 

[pobo]

Re: 1990 75hp Mariner upgrade?

where would i get information on this . I HAVE TWIN 75S I WOULD LOVE TO GO TO 90

 

[emckelvy]

Re: 1990 75hp Mariner upgrade?

The blocks have different part numbers and I'd expect that means different porting.

You might have some luck looking for a good used 90 HP block on eBay and putting the 75hp internals in it.

You should be able to re-jet your carbs to 90hp specs or pick up a set. You'd want to measure the carb throat diameter to see if there's a difference. The parts lists does show different model carbs from one hp to the other.

HTH............ed