1974 70HP Evinrude Prop

[miichael18]

I currently have a 14" with 16 pitch and it looks rough and chipped pretty bad. its not cutting water very well at all. I want to keep the size and pitch the same because it seems to run good with it but i cant find a 14" 16 pitch anywhere? The motor turns about 5400-5500 rpm with the prop now so i dont want to change the size if i can help it. what would be my best choice? here's what i found as far as sizes goes.

14" 17 pitch
13-1/4" 17 pitch
13-3/4" 15 pitch

Which would you recommend me getting? I'm thinking if i get a new propeller that's cutting water good it may tach more than 5400-5500 so i could go with the 13-1/4" 17 pitch but i dont want to loose a lot of rpms with increasing the pitch. But if i go with a 15 pitch plus dropping the diameter of the prop I'm scared it will be too high rpms. I was thinking if i did go with the 13-1/4" 17pitch it would only loose about 200rpm max so that would put me at around 5380-5480 which still should be a good range. plus it may gain a few mph faster?
it is a 1974 evinrude 70hp model 70473-M

also on the prop it is a standard rotation correct?

heres a few pics of the prop on it now to show the damage.

http://i79.photobucket.com/albums/j142/miichael18/100_0423.jpg
http://i79.photobucket.com/albums/j142/miichael18/100_0424.jpg
http://i79.photobucket.com/albums/j142/miichael18/100_0425.jpg

 

[Dhadley]

Re: 1974 70HP Evinrude Prop

Keep in mind that if you drop any rpm you'll be lugging the motor. At 5500 you're on the verge of lugging it now. 5800 - 6000 would be optimum for that motor.

 

[miichael18]

Re: 1974 70HP Evinrude Prop

The repair manual says 5000 WOT

 

[Dhadley]

Re: 1974 70HP Evinrude Prop

I'm not sure where that is or in what context they're talking about -- maybe checking timing? An OE manual or aftermarket? Anyway, that motor will live a lot longer propped at 5800 than it will propped at 5000 on todays fuel. You don't have to run it at 5800 all day, although you can. Won't hurt a thing.

 

[miichael18]

Re: 1974 70HP Evinrude Prop

so which prop do i need?