Am I propped right? 85 evinrude 70hp

[rtpassini]

Finally got to open it up today. GPS said 32 mph. rpms were around 6200.

I dont know what these motors can do, or how fast they should/can spin

 

[TrueNorthist]

Re: Am I propped right? 85 evinrude 70hp

RPM too high. The recommended WOT rpm is 4500-5500 rpm. I would increase the prop pitch and/or diameter.

 

[Chinewalker]

Re: Am I propped right? 85 evinrude 70hp

Rec RPM was 4500-5500 RPM, but it is best to aim for the top, or even a little beyond that upper end. Shoot for about 5700-5800 RPM at wide open with a light load and you'll be in the sweet spot.

 

[rtpassini]

Re: Am I propped right? 85 evinrude 70hp

okay will do. I'll look to see what im at now. Any recommendations on props. I dont need anything special. Also, any recommendations on how much diameter or pitch to go up?

 

[steelespike]

Re: Am I propped right? 85 evinrude 70hp

Remind us what size prop?

 

[rtpassini]

Re: Am I propped right? 85 evinrude 70hp

I wish I knew....just went out and looked. no stampings or marks anywhere.

it seems to be a 13" though....not much room to go up anymore either.

 

[BonairII]

Re: Am I propped right? 85 evinrude 70hp

I assume that 13" is referring to the diameter....not the pitch, correct? I'm guessing that you're running a 15" or 17" pitch.

Pull your prop...the size will be stamped somewhere on it. At the every least, there will be a part# on it.

 

[rtpassini]

Re: Am I propped right? 85 evinrude 70hp

yeah, 13" diameter. given, it different and I was just off.
you would like to think so huh? just pulled it and couldnt find a thing.

side note, how tight should the nut be? it wasnt even finger tight. the cotter pin was doing its job.

at this point, I would be happy with just a good "normal prop for this motor" measurement and go from there. i did find some damage.


Theres a few used 13 1/4 x 17 on ebay
Maybe a 13 1/4 x 19. but those are all new

 

[BonairII]

Re: Am I propped right? 85 evinrude 70hp

17" seems to be a good all-around prop for the 70hp motors. I'm running a 17 on my 75hp(crank rated) @ 5850rpm. It could turn a 19" just fine, but I'd lose quite a bit of holeshot.

Yours being a prop rated 70hp... I'm guessing that 17" would still be the perfect prop. Now if you end up finding out that your current prop is a 17 then def change to a 19p.

 

[rtpassini]

Re: Am I propped right? 85 evinrude 70hp

what about your thoughts on a 13 3/4 x 15?

 

[BonairII]

Re: Am I propped right? 85 evinrude 70hp

I think you'll turn a 15" over 6000rpm....I know that I can pull 6100 rpm when I use my 15, so I have to throttle down a tad.

You're probably running a 15" right now considering your getting 6200 rpm.

 

[jestor68]

Re: Am I propped right? 85 evinrude 70hp

Your motor's rpm range is 5000-6000 rpm. The perfect (hp rated) rpm would be 5500.

Given that your boat's dry weight is about 950 lbs, I would recommend a 17 pitch prop for general duty, and a 15 pitch for pulling water skiers, etc.

 

[steelespike]

Re: Am I propped right? 85 evinrude 70hp

Jestors got this pretty well down but look under the prop nut for a number.
It could confirm your setup is working but needing a 17" for general duty.
The Solas Amita and Rubex are good entry level props with a history of success.