I need help with my mercuiser 120

[rzmuelle]

I just bout a 1980 or 1981 Marquis Riviara with a Mercuiser 120 in it. The boat will pull up skiers but I want to get a little more hp out of it, is there any simple addition I can add to get that. I have tried a 15,75 x 15 pitch 4 blade prop, a 17 and 19 pitch 3 blade prop and all seem to work the same. I also need to know if a 140 drive will fit on a 120? I am new to the boating so I will problly ask some dumb question.

 

[fishingdan]

Re: I need help with my mercuiser 120

No, there isn't really much you can or should do. Changing the prop allows one to adjust the tradeoffs of hole shot and top speed as long as the prop allows you to operate in the proper engine rpm ranges.

- Insure that the engine is properly tuned and in good running condition
- Insure that the outdrive is properly serviced
- Find a prop that best matches your boating needs/wants (there is a good forum here just for prop selection)

Good luck,
Dan

 

[rzmuelle]

Re: I need help with my mercuiser 120

Thanks Dan,
does anyone know if a 140 streen drive will interchange with a 120?

 

[P 0 P E Y E]

Re: I need help with my mercuiser 120

how many rpms?

Looks like your going to need to lighten the load or get a bigger engine package.

If the engine is in tune and running right.

Back in my college days, my Uncle had a 120 on a cobia. When the three amigos went skiing the boat was great, when the whole fam damly went out..the boat would bog.

 

[bigskiohio]

Re: I need help with my mercuiser 120

drives will interchange some of the drives shafts are different lengths, just change it to the right one.

 

[rzmuelle]

Re: I need help with my mercuiser 120

Popeye my Rpm are running around 3900 wot with the 19 pitch and 4000 wot with the 17 pitch.

Thanks for the info Big.

Thanks for the help.

 

[Alumarine]

Re: I need help with my mercuiser 120

WOT for that engine is 3900-4300 I believe.

Popeye my Rpm are running around 3900 wot with the 19 pitch and 4000 wot with the 17 pitch.

Thanks for the info Big.

Thanks for the help.

 

[rzmuelle]

Re: I need help with my mercuiser 120

Thanks for the info Marc c