Prop/pitch

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rzkas

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hI? WHAT IS THE BEST PROP AND PITCH FOR A FORCE 120 ON A 95 BAYLINER CAPRI 19'. CURRENTLY MY BOAT GIVE ME AROUND 32MPH. I USED MY BOAT MOSTLY FOR CRUISING. I WILL LIKE TO GO FASTER THAN 32MPH. WHAT ARE YOUR RECOMMENDATIONS FOR PROP AND PITCH SIZE AND SPEED AND PERFORMANCE IMPROVEMENT.

I HAVE 94 FORCE 120 ENGINE.
 
WIMUSKY

WIMUSKY

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Re: Prop/pitch

What's your current props pitch? What is the rated WOT rpm for that motor? What is your actual WOT rpm?
 
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rzkas

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Re: Prop/pitch

WIMUSKY said:
What's your current props pitch? What is the rated WOT rpm for that motor? What is your actual WOT rpm?
Click to expand...


my boat doesn't have a RPM gauge. my boat only has three gauges. fuel, speed and battery. how can i check the WOT and RPM ? i don't know anything about the pitch of the prop. i know it has three blades and it aluminum.
 
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steelespike

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Re: Prop/pitch

What year is the motor?Your pitch may be near the base of the blades or on the barrel of the prop.
2 numbers; Diameter X pitch.
Its important for performance and the health of your motor that it be able to rev freely within its wot rpm rating.
You can't tell without a tach. With a prop size ,an accurate gps speed your gear ratio ,I believe 1.72 and a guess of the slip
we can guess on the rpm.
 
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rzkas

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Re: Prop/pitch

oK I WILL LOOK AT THE PROP FOR NUMBERS AND MARKING. IT A 95 FORCE 120
 
WIMUSKY

WIMUSKY

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Re: Prop/pitch

rzkas said:
help pls
Click to expand...

Looks like steelespike has you covered.......... If you have the manual for the Force it should tell you the rated WOT rpm. Otherwise, there must be a site that would say. Iboats doesn't list that info for your motor...... I'm not sure where to look..... Someone else probably knows....
 
not enuf toys

not enuf toys

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Re: Prop/pitch

not to be rude or discouraging but 32 on a 19ft boat with a 120 force may be all shes got.
 
jestor68

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Re: Prop/pitch

Rpm range is 4750-5250. I had a 1992 (new) 18.5 ft bayliner/120 Force. I ran a 19 pitch at 5300 rpm @ 47 mph. If memory serves, the gear ratio was something like 1.86.

Bear in mind the boat was new and the motor fresh. Your motor may not be that fresh anymore.
 
R

rzkas

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Re: Prop/pitch

hi how are you? the prop pitch is 20 and it 13" in diameter. is the correct pitch for the engine or what is the best size for this 95 120 force engine on my 95 bayliner capri 18/19'.

how can i find out my RPM and WOT when i don't have a gauge for that on my dash board/gauge console.
 
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steelespike

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Re: Prop/pitch

You may be able to borrow a shop tach from a marina.You can buy a induction tach like a tinytach be sure to tell them its for an outboard. a lazer tach will work though difficult to use on a bouncing boat but do able.
Some very rough calculation your rpm is about 3500 at 32 mph.Even though you probably need less prop(lower pitch)
the 20 should give you some numbers in the ball park with a light load.wot rpm needs to be within the 4750-5250 range
at this point you can't make up the difference with a prop.
You need to check the motor be sure its running on all cylinders,
in excellent tune. Strong compression,Throttle opening all the way.
 
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rzkas

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Re: Prop/pitch

yes motor is in good shape. according to the mechanic that summerize it said the motor is working good. do i need to change the prop or it ok. will this size cause any harm on my motor.
 
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steelespike

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Re: Prop/pitch

I believe around 95 Force started to use the Mercury Leg. The question is when did it change and what gear ratio?
Probably close to the original ratio also I believe it would be a different prop number.
 
R

rzkas

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Re: Prop/pitch

i don't know the gear ratio or when it change. i got the boat the way it is presently. should i change the pitch or keep the pitch?
 
Frank Acampora

Frank Acampora

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Re: Prop/pitch

The Mercury lower unit used after 1992 is about 1.95 to 1. Even with that, a 13 X 20 is too much prop for a 120 on a 19 foot boat--even with a light load. If you are carrying three people or more and a couple of tanks of gas plus fishing or fun gear, you do NOT have a light load and the prop is simply too much pitch.

Try to borrow a 13 X17 prop to test, or buy a relatively inexpensive used one. If it does not increase speed, you can still use it for a spare prop or as a skiing prop.

" Motor is in good shape, according to the mechanic" Unless he tested it with a test wheel or did an on-water test, there is no way to really know. Almost ANY engine in running condition will rev up high on muffs with no load--this means nothing.

You need someone near you to help you check that carbs are opening fully at wide open throttle, fuel pump is delivering adequate fuel, compression is high and equal on all four cylinders, and timing advance is correct. THEN, when you are certain the engine is running correctly, try a different prop.
 
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