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Old 17-05-2015, 05:11   #1
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Join Date: Jun 2013
Location: Newfoundland, Canada
Boat: 30ft Homemade Cabin Cruiser fg/w - Perkins 4-154 62hp
Posts: 8
Transmission Replacement

I got a Perkins 4-154 62hp thats approximately 30-40 years old and works like a charm. The transmission(gearbox) is 2.91-1 reduction. I have no proof how old the trans is because the plate is no longer on it but figure it might be same has the engine. I'm thinking of replacing it with a 2.57-1 reduction. I know this will give me more rpms on the prop but wondering if it will cause any issues with the engine. Any thoughts?
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Old 17-05-2015, 06:39   #2
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Location: Houston
Boat: '76 Allied Seawind II, 32'
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Re: Transmission Replacement

It should only cause you problems with the engine if you keep the prop that was matched to the 2.9 gearbox. If you re prop for the new trans you'll be just fine.

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Old 17-05-2015, 07:56   #3

Join Date: Feb 2013
Location: Boat is on the Rio Dulce
Boat: Seafarer36c
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Re: Transmission Replacement

It should give you about another 100rpm on the prop? Sounds like a lot of money for such a small gain. If you re-pitch the prop you will put more load on the engine and it's kind of old now for changing things.
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men, transmission

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