mercruiser 4.3 1-84r 19" prop over reving 5000-5500rpm

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sdamon

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Jun 14, 2012
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I have a 95 celebrity 180 WITH A 4.3 MERCRUISER alpha one gen two 1.84r.19" prop engine over reving.Is this the correct ratio for the 4.3 205 hp 4 bar carb.
 
Don S

Don S

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Re: mercruiser 4.3 1-84r 19" prop over reving 5000-5500rpm

Yes, it is the correct ratio for a 4.3. Are you sure the tachometer is correct?
That really sounds like too little pitch for that size boat, so will move this over to the prop forum for you. They can probably help you choose the correct prop.
 
picklenjim

picklenjim

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Re: mercruiser 4.3 1-84r 19" prop over reving 5000-5500rpm

Yes that's correct. Try a 21 or 23 pitch prop. Also is it a good prop your using and are you sure your tach is correct?
 
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sdamon

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Re: mercruiser 4.3 1-84r 19" prop over reving 5000-5500rpm

I know the tachometer is correct because the enigne is screaming. And did have 21 pitch prop on there and it seemed to have the same RPM.
 
achris

achris

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Re: mercruiser 4.3 1-84r 19" prop over reving 5000-5500rpm

I had the same engine in the boat in my signature, and that was running a 21", and still pulling over 5000... Your boat's smaller than mine (by quite a long way) and it sounds like you might be running out of propellers... May be time to look at changing the ratio to a 1.65:1... That will get you back into the 19/21 area...

Chris....
 
90stingray

90stingray

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Re: mercruiser 4.3 1-84r 19" prop over reving 5000-5500rpm

My setup is about the same... so i hope this helps. My 4.3 with 1.8 ratio drive runs 4800 with 23p 3 blade aluminum. 4650 with a 21p 3 blade ss. Both get me around 50mph. Change your prop.
 
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bigblank69

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Re: mercruiser 4.3 1-84r 19" prop over reving 5000-5500rpm

Definately need a prop change. I have a 4.3L with 1.81 Ratio, When I had a 14.25x21P 3 Blade Alum prop on there I couldn't get to full throttle without smacking the Rev Limiter, switched a to a High 5 21p and got the same results. Switched to a 23p 3 blade Alum and got the RPMs in check and picked up speed, going to trying out a 21p 4 Blade SS prop this weekend to see if I can keep the RPM's in check and get some additional bite, if it doesn't work I'm going to try a 23P High 5.

Try a 23p Alum and see if that brings you into your RPM Range and then you can start dialing in after that...
 
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mr-steve-jones

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May 6, 2011
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Re: mercruiser 4.3 1-84r 19" prop over reving 5000-5500rpm

I run my 2052 Bayliner 4.3V6 Alpha 1 Gen2 1.84R with a 23" Laser 2 at 4800RPM at WOT when driving about, and prefer a 21" and down throttle 4600 - 4800 range manually to the when towing inflatables... Better acceleration.

Looking for a used High 5, 21" to try for the towables..
 
achris

achris

More fish than mountain goat
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Re: mercruiser 4.3 1-84r 19" prop over reving 5000-5500rpm

mr-steve-jones said:
... and prefer a 21" and down throttle 4600 - 4800 range manually to the when towing inflatables... Better acceleration...
Click to expand...

Ahhhh, someone after my own heart. :D

My current rig would be 'perfectly propped' with a 19". It pulls 4600 WOT, but I run a 17", it's more 'driveable', with better speed holding in heavy swells, and the engine runs cooler, and the drive is less loaded.... The only downside is on the days when I can WOT (about 2 a year!) it'll pull to the rev limiter (4950). And for the nay-sayers, no it's doesn't use any more fuel. I have a fuel flow meter and regardless of the prop, for the same boat speed, the fuel consumption is EXACTLY the same....

Chris.......
 
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bigblank69

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Jul 22, 2011
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Re: mercruiser 4.3 1-84r 19" prop over reving 5000-5500rpm

mr-steve-jones said:
I run my 2052 Bayliner 4.3V6 Alpha 1 Gen2 1.84R with a 23" Laser 2 at 4800RPM at WOT when driving about, and prefer a 21" and down throttle 4600 - 4800 range manually to the when towing inflatables... Better acceleration.

Looking for a used High 5, 21" to try for the towables..
Click to expand...

How much are you looking to spend? I have a Qst 5 21p (quicksilver high 5) in the box i wanto swap for a 23p version..
 
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