Mercruiser 120 Prop

[eman225]

I have a 1976 Aristo-Craft 19 with a Mercruiser 120 and was wondering what the maximum prop pitch for this enginge should be. It's pretty quick with my 17 pitch but I was wondering if I could use a 19 or 21 pitch without it putting too much of a strain on the drivetrain.

 

[87concord]

what rpms are you turning at WOT?? If there is one thing you will learn on this site is that you need to post as much info as possible. The guys on here are great but they need as much accurate info as possible to help you

 

[chiefalen]

like it was just posted wot has has to be i believe between 4200-4600 rpm. speed is unimportant. And wot on a old girl like you have should just be maintained for a few minutes, it is also recommended that you run at 3/4 wot.

 

[eman225]

I normally operate it around 3/4 throttle. I believe the maximum rpm is around 4300. I rarely go all the way.

 

[sandkicker]

If you are at 4300, which is at the low end of the OK range, then it is highly unlikely that you'll be able to swing a higher pitch prop. Going to a 19 or 21 pitch, will eventually result in engine damage.