88 hp Evinrude SPL prop???

rickdb1boat

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Re: 88 hp Evinrude SPL prop???

walleyehed + harpjames35 <br /><br />If I might jump in here for a sec. You should be able to turn a cupped 17" prop on a 15' runabout with no problem and at least hit 5500 RPM's and 40 MPH with that motor. Heck, my sis-in-law has a 24' toon with the 88 on it, running a 14" X 13" prop and it hits 5600 RPM's.Something is amiss here. I would try another prop and go with at least a 17" pitch. It Can always be re-pitched to a 15" or 19" if nessesary. Also, for a comparison, I had a 1967 Merc 65 HP turning a 17" pitch prop at 5500 RPM's on a 15" Wellcraft runabout and it hit 37 MPH. So, I would have to assume you would do better with the 88HP on yours. According to the prop selector, you should be running a 14" X 21" pitch for your size boat with a light load. My Wellcraft is a pretty heavy 15'er, hence the 17" pitch on the 65 HP motor. Either your Tach is wrong, the speedo is wrong, the prop pitch is wrong or the motor is not up to snuff. Try to borrow another tach and see what it reads. That's what's important right now. Then you can determine if you are even close to having the correct prop.Any numbers stamped on the hub of the prop you have now?
 

harpjames35

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Re: 88 hp Evinrude SPL prop???

GOTCHA. I usually use 89, but I'll make sure to keep it at 87 or 89. Well I greatly appreciate your help. So in conclusion, if I found some extra money, do you think it would be benefitial after I change the plugs, to put a 13 1/4 x 15 prop on there thats new? Thats APPEARS to be the size thats on there now, correct? So would a new one of the same size without any scraped,bent,or nicked fins be worth trying?
 

harpjames35

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Re: 88 hp Evinrude SPL prop???

No problem with Idle or starting at all. Starts quick and idles fine with no fluxuating of rpm<br /><br />Rick: No numbers or info stamped on prop anywhere.
 

rickdb1boat

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Re: 88 hp Evinrude SPL prop???

I would not get anything lower than a 14" X 17" prop for your rig. It should be able to turn that easily. If you get a new one, it will have some cup to it. That is good.
 

walleyehed

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Re: 88 hp Evinrude SPL prop???

Rickdb1boat- in figuring his indicated speed and RPM, I'm assuming a 15", and am leary because of the same reason you posted....This SHOULD spin the H_ll out of a 15"...tach, or speedo-I would trust the tach first, and at that rate, I would say we've got a problem engine-wise...no????<br /><br />James, can you verify the butterfly's are opening against the rollpin stop at WOT???<br />If they are, the next item would be max timing advance, which we can determine that figure via manual....
 

rickdb1boat

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Re: 88 hp Evinrude SPL prop???

walleyehed<br /><br />Right you are!<br />That's where I'm kinda heading with it. That's why I recommended nothing less than a 17" prop.
 

rickdb1boat

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Re: 88 hp Evinrude SPL prop???

harpjames35 <br /><br />This is kind of out there, but when you installed the tach, did you set it on "6" pole? Just a thought...
 

harpjames35

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Re: 88 hp Evinrude SPL prop???

Rick: I tried that prop selector webpage, and it returned two props: 12-3/4 x 21 and 13-1/4 x 21. According to yours and walleyehed's suggestions, doesnt 21" seem high?
 

harpjames35

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Re: 88 hp Evinrude SPL prop???

Rick: the tach that I have has a +, -, and sender wire. Then there is a dial that gets set on 1, 2, 3, or 4 which I am assuming that is cylinders, so its set on 4.
 

rickdb1boat

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Re: 88 hp Evinrude SPL prop???

I would say a 21" would be a little high, as they tend to recommend toward the lower range of the RPM band(5000-5500). You want a prop that will let your engine turn between 5800-6000 RPM's with a normal load. If it were me, I would get 14" X 17" prop and go from there. Most prop shops will let you try one out and return it if it's still like new when you bring it back. And as I said, you can always have it re-pitched 2" either way, for a small fee if need be.
 

rickdb1boat

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Re: 88 hp Evinrude SPL prop???

The Tach you have may be the key here. Most tachs have settings for 6 poles. I'm not really sure what the setting on that one would be correct, but it could very well be on the wrong one and giving you false readings. Have to check into that one further. Tach may be incompatable with your motor.
 

rickdb1boat

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Re: 88 hp Evinrude SPL prop???

for now, I'm just tossing out round numbers as far as the prop goes. No substantial difference.<br /><br />13-1/4 X 17 is the one I'm really talkin' about.
 

rickdb1boat

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Re: 88 hp Evinrude SPL prop???

If I might suggest, start a new post expaining the type of tach you have and the setting it has. Ask if it will work and what the seting should be. Title the post:Tach Settings
 

walleyehed

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Re: 88 hp Evinrude SPL prop???

Rick, my original choice on prop as well....<br />I've got a teleflex tech here in the shop, I'll look it over and see what the deal is....there should be a "6" position on that tach, James.....<br />I'll get back to ya.
 

harpjames35

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Re: 88 hp Evinrude SPL prop???

Thats a good idea, but I have no idea what the manufacturer is. It doesn't say on the tach and I bought it open box on clearance. The boat shop told me that was the right tach but who knows.<br /><br />Would posting a topic just explaing the different poles that it has, and explaining about the dial setting be sufficient enough to get responses?
 

rickdb1boat

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Re: 88 hp Evinrude SPL prop???

Kenny, I have a Teleflex tach and it has a 6 pole setting as well. every tach I've bought had a 6 pole setting. That's why I believe it may be the wrong type tach.
 

rickdb1boat

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Re: 88 hp Evinrude SPL prop???

harpjames35 <br /><br />Yes, that would be enough for some more of the more experienced to figure out quick.
 
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