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Sun, December 22 2024, 01:09 [ Login ] [ Contact Forum Admin ] [ Main index ] [ Post a new message ] [ Search | Check update time | Archives: 1, 2, [3], 4, 5, 6, 7, 8, 9 ]

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Date Posted: - Saturday - 05/28/11 - 1:38pm
Author: Brian
Subject: Prop Size
In reply to: Alan Gallagher 's message, "Mariner 40 Propeller size" on - Friday - 04/29/11 - 7:21pm

A very crucial piece of information is the transmission ratio. On the Borg Warner it is located on the port side, just forward of the shifting lever and fill plug. It is on a brass placard. Mine was very rusted and need to be cleaned up.
Some of the M31's & M32's are 1-1. My M36 is, (I have to check to make sure) 2.98-1. This puts the prop rpm between 670 at 2000 rpm to 940 at 2800 rpm.
We updated the prop shaft to 1 1/4", with a standard american taper. The original was 1 1/8" with a metric taper. I would be guessing at the prop we put on. I will check the next time I'm the boat.
I have an engine & Trans from a 1967 M40. The trans is horribly rusted and the ratio plate has been removed.

Brian 1973 M36 Gran Mariner

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Replies:

[> prop size -- Brian, - Friday - 06/ 3/11 - 4:20am

The Trans ratio is - 2.57 -1. The prop that I put on is a 3 blade left hand 18X10. The motor is a Perkins 4-107.With this prop the engine can make around 2600 rpms.
The original prop was 2 blade 18X12 Left hand.. I jope thid this helps.
Brian 1973 M-36


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[> [> prop size -- Alan Gallagher ((o:), - Sunday - 09/11/11 - 6:07pm

Thanks Brian - I have a Perkins 4-108 - so I'm not sure that your 18x10 would work - thanks for your time my friend


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[> [> the 107 and 108 are the same -- Paul M31 #106 NJ, - Monday - 09/12/11 - 8:40pm

except for some specific design detail, such as replaceable cylinder linings on the 107 - I am not familiar with the exact differences, but in principle the engines are the same. Cnances are, though, that you may have a 1:1 transmission, which indeed would have a major effect on the prop.

I have the Perkins 4-107 and it swings a 13 x 8 three bladed fixed prop and it sits exactly on the engine's power curve. This means that for my M31, at about 1600 rpms, it delivers around 22 to 25 HP, enough to push the boat at an easy hull speed.

Max RPM with this prop is around 2200, at which poit the boat digs deep and runs at about 7.2 kts, well above hull speed and she just won't go any faster and drags the prop.


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