different gear ratios?

pinecreek

Cadet
Joined
Jun 19, 2010
Messages
7
hey everyone. i have a 91 glastron g1700 with a 140 mercruiser 3 liter. 1.98 r. the upper unit took a dump and i am not quite sure on the lower. i would simply like to find another unit that has been rebuilt already upper and lower and just swap...i found one has 3 hours on it rebuilt from local marina. but its a 1.84r gen 2 i also have a gen 2 by the way. will this work? i have lots of props to choose from, if i need a different one. it doesn't seem like a big change, but maybe it is. i read people going from 1.94 to 1.47, and loosing all power. thats bad, but i dont' know! please help! this 1.84 is from a 4.3ltr. all we do is puts around, occasionally do we open it up.
 

Bifflefan

Commander
Joined
May 27, 2009
Messages
2,933
Re: different gear ratios?

I may step on my tounge here but, isnt a 91 a gen 2?

As for the differnet ratio, id think you could prop that much difference. But i have never tried it.

What does the marina say that has the new drive?
 

180shabah

Rear Admiral
Joined
Mar 26, 2005
Messages
4,995
Re: different gear ratios?

I may step on my tounge here but, isnt a 91 a gen 2?

91 is the year the gen2 was introduced, but they are not on all 91 boats. That was up to the manufacturer and the amount of inventory they had remaining.

However, the OP states that he has a gen2 and the rpl drive is also a gen2.

OP - get the correct gear ratio - there is a reason merc used more than one.
 

pinecreek

Cadet
Joined
Jun 19, 2010
Messages
7
Re: different gear ratios?

for such a small gear change? has anyone done something like this before? i have not talked to the marina, only asked if they had some rebuilt alphas laying around...
 

Bondo

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Staff member
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Apr 17, 2002
Messages
71,082
Re: different gear ratios?

for such a small gear change? has anyone done something like this before? i have not talked to the marina, only asked if they had some rebuilt alphas laying around...

Ayuh,.... What pitch prop were you runnin' with the 1.98,..??
 

180shabah

Rear Admiral
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Mar 26, 2005
Messages
4,995
Re: different gear ratios?

How much are they charging for this rebuilt unit?
 

pinecreek

Cadet
Joined
Jun 19, 2010
Messages
7
Re: different gear ratios?

the prop on it now is a 21p 3blade. revving 4700 at 46mph going from the boat tach and speedo. and they are charging 1200 for this unit. as for blade switching i was thinking a 4 blade 24?
 

Bondo

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Staff member
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Apr 17, 2002
Messages
71,082
Re: different gear ratios?

the prop on it now is a 21p 3blade. revving 4700 at 46mph going from the boat tach and speedo. and they are charging 1200 for this unit. as for blade switching i was thinking a 4 blade 24?

Ayuh,... That's about the price of a Brand New SEI drive... With the Right ratio...

Naw, more like a 3 blade 15" or 17"...
 

nola mike

Vice Admiral
Joined
Apr 22, 2009
Messages
5,410
Re: different gear ratios?

for such a small gear change? has anyone done something like this before? i have not talked to the marina, only asked if they had some rebuilt alphas laying around...

yeah, the sei's are $1300 or so with a warranty...anyway, i just went the other direction, from a 1.84-->1.98. changed prop from a 23p-->25p, all seems well.
 

180shabah

Rear Admiral
Joined
Mar 26, 2005
Messages
4,995
Re: different gear ratios?

As mentioned you are thinking the wrong direction on the prop change. Just a few pennies more will bet you a BRAND NEW drive.
 
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