89 merc 5.0 lx with a 1.84 alpha one??

Y

yrubugn

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Jun 21, 2012
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Didnt notice this when I bought the boat but the PO replaced the outdrive w/ a gen1 1/1.84...I see it should be 1/1.5

I have been battling a WOT surging issue and was wondering if this may be the cause?

Maybe I could just change props to counter the drive difference? Could I continue to use this safely?

The boat is a 21 foot cabin cruiser

TIA for any replies
 
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yrubugn

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Re: 89 merc 5.0 lx with a 1.84 alpha one??

Sorry please move to mercruiser...
 
Bondo

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Re: 89 merc 5.0 lx with a 1.84 alpha one??

yrubugn said:
Didnt notice this when I bought the boat but the PO replaced the outdrive w/ a gen1 1/1.84...I see it should be 1/1.5

I have been battling a WOT surging issue and was wondering if this may be the cause?

Maybe I could just change props to counter the drive difference? Could I continue to use this safely?

The boat is a 21 foot cabin cruiser

TIA for any replies
Click to expand...

Ayuh,... That ratio will cause Over-revin', but not surgin'.... That's usually a fuel delivery issue...

I kinda doubt you'll find a prop Big enough to fix the ratio issue...
 
Y

yrubugn

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Re: 89 merc 5.0 lx with a 1.84 alpha one??

So to bring rpms down I would want larger diameter prop or higher pitch or maybe both....

I have 17 fitted now.
 
Don S

Don S

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Re: 89 merc 5.0 lx with a 1.84 alpha one??

At what rpm is this surging?
 
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yrubugn

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Jun 21, 2012
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Re: 89 merc 5.0 lx with a 1.84 alpha one??

Not 100% as the tach is erratic I guess in the 3500-3800 range.

Thinking its tune related engine still fitted w oem mercruiser parts it looks like, seemed to improve after running a bit both times out this year...
 
achris

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Re: 89 merc 5.0 lx with a 1.84 alpha one??

yrubugn said:
So to bring rpms down I would want larger diameter prop or higher pitch or maybe both....

I have 17 fitted now.
Click to expand...

Higher pitch... and you are going to need to go to about 23 or 25...

With that 17" prop I suspect the engine is so over-revved that it's just running out of breath, hence what you feel as surging...

Chris....
 
achris

achris

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Re: 89 merc 5.0 lx with a 1.84 alpha one??

yrubugn said:
Not 100% as the tach is erratic I guess in the 3500-3800 range.
Click to expand...

That could indicate an ignition problem... Is the tacho erratic in other rev ranges?
 
Y

yrubugn

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Re: 89 merc 5.0 lx with a 1.84 alpha one??

Seems to generally flutter or be off in higher ranges

Just reched my prop its a 19
 
achris

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Re: 89 merc 5.0 lx with a 1.84 alpha one??

What spark plugs are in?
 
Don S

Don S

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Re: 89 merc 5.0 lx with a 1.84 alpha one??

You have engine problems, not prop problems right now. You have an outdrive gear ration for a V6 and with a 17 or a 19 prop you should be hitting close to 6 grand with your 5.0LX

You need to get an inductive tach on a timing light or something and find out what rpm you are actually getting. But before you test, disconnect your helm tach and take it out of the equation.
 
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