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TOPIC: Prop questions...again.

Prop questions...again. 18 Jun 2018 15:14 #85885

Service manual states WOT is 4500 rpm. Would the 13.25 get it close to that?
Again, tough question.

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Last edit: by chriscraft.

Prop questions...again. 18 Jun 2018 12:25 #85884

chriscraft wrote: Very minimal load and just myself at 220 lbs. Would it be possible for the 13.25 to increase the rpms upwards of 1000?


Going from a 14 pitch to a 13.25 pitch I don't think will increase it 1,000 RPM, more likely 400-500 RPM. The other variable is, will the speed increase? That will add RPM's as well.

I'm not sure of the gear ratio of the older lower unit, if someone can provide that this calculator will give a very close estimate of the change.

www.rbbi.com/folders/prop/propcalc.htm

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Ray

"Every man takes the limits of his own field of vision for the limits of the world."
Arthur Schopenhauer

1956 Vagabond I - 50 HP Johnson
1950 Flyer - 50 HP Evinrude
1/2-195something Flash - KG7
1956 Golden Rocket, Sawzall Special
Last edit: by Locomotion.

Prop questions...again. 18 Jun 2018 11:04 #85883

Propeller options for that motor (in regards to pitch) are 14,13.25, 12.5 or 11.5.
I know where I can find a new OEM 13.25.

Thanks
Mark

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Prop questions...again. 18 Jun 2018 10:58 #85882

Very minimal load and just myself at 220 lbs. Would it be possible for the 13.25 to increase the rpms upwards of 1000?

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Prop questions...again. 18 Jun 2018 00:27 #85879

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I'd try a 13.25" pitch.

Maybe even a 12"

Aim for a wide open rpm to be almost right at 5k with a lightly loaded boat and just you in it.

That way when you have passengers and more of a loat the motor will still be in it's safe operating range. 3,900 rpm is too low and is not good for the motor.

How was you boat loaded?
Just you and gear?

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Just beyond the breakers.

Other 1/2-195something Flash - KG7
Last edit: by VinTin.

Prop questions...again. 18 Jun 2018 00:04 #85878

So I put another couple wraps (total of 4) around the plug wire. That seemed to settle it down. Here is the skinny on the my prop situation with the new information.
WOT rpms in the 3900 range.
Top speed just under 25 mph with the 14 pitch prop.
Plugs are a perfect brown indicating I have the carb dialed in.
So do I go to the suggested 13.25 pitch is my question.
Thanks to all for your input.
Mark

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Prop questions...again. 17 Jun 2018 20:58 #85873

jabe wrote: mine wasn't bad, i was comfortable if it altered a couple hundred rpm, least i know what ball park i am in, it did do a couple 1000 rpm jumps that had me concerned.........i will look into sheilding the wraps on the wire and see what happens


You can wrap a wire around the other plug wire and ground ONE end and cut way down on the RFI it is putting out.
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Ray

"Every man takes the limits of his own field of vision for the limits of the world."
Arthur Schopenhauer

1956 Vagabond I - 50 HP Johnson
1950 Flyer - 50 HP Evinrude
1/2-195something Flash - KG7
1956 Golden Rocket, Sawzall Special

Prop questions...again. 17 Jun 2018 20:32 #85872

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mine wasn't bad, i was comfortable if it altered a couple hundred rpm, least i know what ball park i am in, it did do a couple 1000 rpm jumps that had me concerned.........i will look into sheilding the wraps on the wire and see what happens

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57' Fleet Ranger111-
57' Fleet Cartopper-
53' Deluxe Runabout-
56' Johnson's...Javelin, 2 x 30,15, and 7 1/2 hp
we have not inherited the earth from our fathers, we are borrowing it from our children

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Prop questions...again. 17 Jun 2018 20:23 #85870

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jabe, I'm not sure what is causing the variation. Mine varies a little bit but "not all over the place" as stated by chris craft. The speed of my boat also varies a little on my GPS. Mabie it's just the nature of these electronic devices.

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John

1958 Vagabond II & 35 HP Evinrude
1955 PlastiCraft 12 Ft. Delux Runabout
1957 Clipper & twin 35 HP Evinrudes
1957 AlumaCraft 14 Ft. FD

Prop questions...again. 17 Jun 2018 19:55 #85868

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i tried my Tiny Tack out today as well......was running a 12 1/2 pitch prop that Alan lent me........got readings of 3800, up and down a couple hundred, not sure either what that was about, i swapped out to a 11 1/2 pitch, got a consistant, 4200-4300........same mph on both.....the Javelin sounded so sweet........she is a keeper, and will be mounted for Gower Island this week.......:biggrin:
John you figure the variation is interference?

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57' Fleet Ranger111-
57' Fleet Cartopper-
53' Deluxe Runabout-
56' Johnson's...Javelin, 2 x 30,15, and 7 1/2 hp
we have not inherited the earth from our fathers, we are borrowing it from our children

uppercanadachapteroftheaomci.yolasite.com/
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