2.5/153 need info

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Bowtieboy

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New to the site, need some info on my boat project. My 86 Glasstream has the 3.0l OMC and is freeze cracked. I have access to a mid 60's 2.5/153. Can I use my 3.0 head on the 2.5, and what about the rotating assembly from the 3.0, could I use it in the 2.5 also? Any info is appreciated. Im a pretty good mechanic and can handle the rebuild with no problem, just thought I would lean on you guys with more experience in the marine business.
 
Bondo

Bondo

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Re: 2.5/153 need info

Bowtieboy said:
New to the site, need some info on my boat project. My 86 Glasstream has the 3.0l OMC and is freeze cracked. I have access to a mid 60's 2.5/153. Can I use my 3.0 head on the 2.5, and what about the rotating assembly from the 3.0, could I use it in the 2.5 also? Any info is appreciated. Im a pretty good mechanic and can handle the rebuild with no problem, just thought I would lean on you guys with more experience in the marine business.
Click to expand...

Ayuh,.... Welcome Aboard,... The Head will probably work, the rotatin' assembly, Won't....
 
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Bowtieboy

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Re: 2.5/153 need info

Glad to be here, hoping to learn a bit from you guys. Providing that the 3.0 head does work on the 2.5, it would be the better choice of the two, would you agree? The 3.0 head and the cam from the 3.0, should be a pretty solid combo in the 2.5 I would think. Let me know If I'm on the wrong track.
 
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Maclin

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Re: 2.5/153 need info

My first thoughts are that the 2.5 (assuming it is the marine version) has a higher RPM power band and the gear ratio in the drive may not be a good match. I bet you can find another 3.0 to work with which in my opinion would be a better path to take. The "No replacement for displacement" tenet applies :)
 
888

888

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Re: 2.5/153 need info

Maclin said:
My first thoughts are that the 2.5 (assuming it is the marine version) has a higher RPM power band and the gear ratio in the drive may not be a good match. I bet you can find another 3.0 to work with which in my opinion would be a better path to take. The "No replacement for displacement" tenet applies :)
Click to expand...

Gear ratio in 2.5 or 3.0 was/is the same
 
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Maclin

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Re: 2.5/153 need info

Thanks 888, I believe I am confusing a 2.3 and a 2.5.
 
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Bowtieboy

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Re: 2.5/153 need info

So the 3.0 head and cam will work with the 2.5? What kind of power would I be looking at?
 
Howard Sterndrive

Howard Sterndrive

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Re: 2.5/153 need info

I don't think the cam will swap. cam bearings on a 3.0 are a different part number than a 2.5
They look larger in the parts book too.
 
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Bowtieboy

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Re: 2.5/153 need info

I would really like to stick with the 3.0 but the price and convenience of the 2.5 is pushing me that direction. Will I give up much in the way of power and performance? Doesn't seem like it would be enough to be a big factor, maybe 10hp or so.
 
Bondo

Bondo

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Re: 2.5/153 need info

Bowtieboy said:
I would really like to stick with the 3.0 but the price and convenience of the 2.5 is pushing me that direction. Will I give up much in the way of power and performance? Doesn't seem like it would be enough to be a big factor, maybe 10hp or so.
Click to expand...

Ayuh,.... The 2,5l is 120 hp, 'n the 3.0l is 140 hp....

Mixin', 'n matchin', get's ya pretty much those same numbers....
 
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