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AQ 125 WITH A 280

K

kmaub

New member
Hi all

Wondering if someon

Hi all

Wondering if someone could answer this question

I want to slow my boat down and thought I would change out my prop.

I have a 15.5 X 19 on the boat now and it works great go out come in.

A friend gave me a spare prop off his boat to try out it is a 14 X 17

Will this do what I want with out causing any problems. I don't want to blow up my motor or damage any thing

Thanks for any help
 
"Do you want to slow down your

"Do you want to slow down your boat at low RPM or at high RPM? The latter is easy, just don't give it too much throttle. To slow it down at low RPM, you may need a different prop.

What are the WOT RPM that you are achieving with your current prop? The 14x17 will slow your boat down but it will bring an increase in RPM at WOT. Make sure you don't go above the max RPM for which your engine is rated.

A 15.5x19 seems to me a bit too much diameter for a 17.5' boat, unless you want it for thrust rather than for speed. I had some time ago a 15x15 on a 17.5' boat with an AQ140A and I liked it because I could go as low as 3500 engine RPM while doing 14.5 knots and still keeping the boat on the plane. It was a good arrangement to run in rough weather."
 
I'm going through the chan

I'm going through the channel at 5 MPH and running at 1000 RPM...speed is too fast people don't like it too much wake
I was told 1000 RPM at idle is right but I'm still to fast for the channel
So if I'm at 5 MPH in the channel I can't troll either and thats what I would like to do
Keep the idle speed up but slow to 2 MPH
I'm not worried about kick a** speed. Right now I can put 4 adults in the boat and come up on plain with no worries and run around 4000 RPM
 
"I would try 15x15 or 15x13; o

"I would try 15x15 or 15x13; or 14x15 or 14x13. You won't get much speed reduction with a 14x17.

Also, make sure the gearset is your outdrive is 2.15:1, which is the correct one for a 4 cylinder engine. If you have a 1.61:1, your RPM at idle will be too fast."
 
"You have not stated what boat

"You have not stated what boat size etc You have, but to obtain Your wishes I think You may have to go rather unconventional.
If I get it right, You want Your boat idle speed at a minimum, something below 5 knots. That is mainly a combination of idle RPM and propeller pitch.
A rough calculation of Your present set (19" Pitch) up gives 7,2 knots at 1000RPM, prop slippage not taken into consideration.
Going down on pitch The result might be as follows:
19" = 7.2 (present)
17" = 6.5
15" = 5.7
13" = 5.0

The Dia 15.5 indicates You are not running a Volvo original prop? Anyway it indicates a rather big dia for an Aq125, they normally go about 14" dia in that pitch area.
In order not to over rev completely when planning I might suggest the totally un-orthodox selection of the Volvo Wide Blade 16" x 13". At 4000RPM it will give a nominal (slip excluded) speed of 19,9 knots."
 
Yes my boat is 17.5 ft bowride

Yes my boat is 17.5 ft bowrider

Thanks for your help guys much appreciated

I'm going to the prop shop in the morning and

with all the info in hand I'll see if I can get

a trade as my 19" is brand new (came with the

boat). I think the young fella was pulling a

tube and thought the bigger the

better.

Thanks again
 
"Rick, consider that your WOT

"Rick, consider that your WOT RPM is critical, even on a smaller boat.
All manufacturers want us to stay within these specs.
I'd be propping this for the correct WOT RPM, and forget the rest.

Now, you mention 1,000 rpm.... may I assume this if your idle rpm?
If so, this is both too high for any cone clutch shifting, and for any decent No Wake speeds. IMO.
An idle this high may prevent you from a good IN GEAR to NEUTRAL shift, and my put you at risk while at/near the dock or another vessel.
IOW's, when the idle is this high, the cone clutch mechanism will not easily dis-engage from either gear.

Just a thought on that!

."
 
"Hi Ricardo,

I have never g

"Hi Ricardo,

I have never gone to WOT with this boat it seems to go way past what I was recommended (up to 5000 RPM) but I found I could do 32 MPH at 4000 RPM and for me that was pleanty and the boat preformed very well.

The only thing I can't do was to slow to 2 MPH for trolling not to mention everyone getting a little ticked at me for going to fast in the channel

Yes my idle RPM is 1000 in gear 1500 in neutral

So now I have to find my WOT RPM rating and go from there

Thanks

I'll get back to every one when I found out"
 
"This is what I found on anoth

"This is what I found on another forum to find out the gear ratio of my 280 his question was about the same as mine

"I have a 1984 AQ280E Volvo sterndrive.In order to prop the boat for its max performance, everyone asks what the gear ratio is. I know it's one of three, 1.61,1.89, or 2.15. The tag # on top is PZNR28158951B."

The letter designation at the end of the serial # tells you the ratio:
B = 1.61:1 C = 1.89:1 D = 2.15:1


2.15:1 for 4 cylinder engines.

So I have come to these conclusions

1) my Motor is a AQ125A
2) It'a a 2.13 L
3) It's output is 117 HP
4) max RPM is 5000 RMP
5) and the gear ratio is 2.15:1 based on the # on top of the drive unit 28152684D

Does this make any sence or am I barking up the wrong tree

So I'm thinking a 15X15 would be the prop for me

Now it's time to call the prop guy

Thanks guys"
 
"Rick, that Alpha designation

"Rick, that Alpha designation is correct.... however, it's only as good as your assurance that no one has changed the transmission on your drive. Lots of these parts easily interchange!

Best to remove the prop shaft carrier "Ring Anode" and expose the ratio that is stamped into the carrier.
Now, that too is only good if no one has changed a gear set. Most of the time, it's accurate.

Listen, the WOT RPM test is to determine if the correct propeller, drive ratio, engine, etc.... are all working together, and correctly.
The risk in not having a good WOT, is "Over-Burdening" your engine..... if over-propped for example...., regardless of which RPM you typically run at.

So by all means prop DOWN if you need to reduce your fishing trolling speed and/or no wake speed.
And more importantly, check your tachometer, set your idle RPM to specs, and don't let this drive make hard shifts into gear due to a high idle RPM.


Rick, I'd start with your WOT RPM test, but only after you have verified your tachometer reading.... and I say that because of your 1,000 rpm idle.... it may not be that high if you can get it out of gear into neutral easily while in the water.

Best I can offer you at this time."
 
"Hey Ricardo

As we have bad

"Hey Ricardo

As we have bad thunderstorms here today and the wind is going to be up tomorrow all testing will be on Monday

But after reading most of the day, talking to the prop guy and the help here I now have a good undaresatanding of what I have and what I want to do.

Much appreciated

I'll let you all know how I make out

Thanks"
 
"Well I found that a 15.5 X 17

"Well I found that a 15.5 X 17 is the best that I can get for my boat so that worked really good

Next problem is we took the boat last week end and it started missing at the dock. Give it a shot of speed and it would take off but run rough.

So I decide I'm going to change the plugs and clean things up.

I took off the distributer cap and the contacts are a little burnt. Cleaned and replaced cap

Pulled carb and cleaned that too

Now it won't even start
No consistant fire from the plugs and it back fires when trying to start.

Can the coil be tested in the boat and what am I looking for when testing?
I was told using an ohm meter one connection to one outside post and the other inside where the wire goes to the cap. should read 0
then go to the other post and same thing should read 0
I get no reading.
Going from post to post I get 0.004

So now I'm waiting for a rotor & cap.
Out of 5 places that sevice Volvo no body carries these parts in stock
"
 
"Thanks EI, read that one afte

"Thanks EI, read that one after my post.

Tested at 3.5 ohms so that means its good.


Yup the wires are in the correct order.


I did a compression test and it is at 150 to 155 psi across the 4 cylinders cold engine.

Spec calls for 130 psi. Is this for a warm engin?"
 
"The test is best done with a

"The test is best done with a warm engine, but if you do it cold it is also OK (the readings will be slightly lower than with a warm engine). The readings you posted look good to me."
 
"Then one thing down on to the

"Then one thing down on to the timing then

This is starting to get frustrating

I go from a boat that runs great to one that don't run at all


hmmmmmmmm"
 
"Sorry for insisting, but are

"Sorry for insisting, but are you sure you did not install the cap 180º off? Or swap wires 2 and 3? It seems odd that it backfires if you haven't changed the distributor's position ...."
 
no problem

I did check to

no problem

I did check to see if i was 180 out as well but there is a sticker on the front of the cap that states to make sure the cap is secure befor starting the engin

If I were out 180 I wouldn't be able to read the sticker

So I have checked spark at he coil and I have plenty I have lots of fuel going to the plugs

Just not very good spark at the plugs and these are brand new out of the package (second set at that)they haven't even been in the block yet plug wires were brand new last fall.

Timing is right on the mark as well

The only thing I can't change is the cap and rotor untill hopefully Tuesday
 
"Did you check the gap in the

"Did you check the gap in the park plugs? It should be around 0.028 to 0.032.

You can also try to hotwire the + of the coil with the + of the battery and see if it starts. Remember that if it does start you will have to remove the jumper to stop it.

Also, did you reinstall the carb correctly? Gasket with the intake manifold is OK? Did you alter the idle mixture or idle speed screws?"
 
Yup gap of plugs is 0.030

y

Yup gap of plugs is 0.030

yup gasket to the carb is good was new came with the boat in the tool box.

nope I didn't mess with the mixture but I have been playing with the idle to get my RPMs down

that is what I wanted to do when I took the boat out last weekend was to adjust the idle but I never got a chance as it started running rough then. So we just went fishing brought the boat home and I though I would just have to change out the plugs and the little missing would go away. BOY WAS I WRONG EH!
 
Well here we are.

I finally

Well here we are.

I finally got my parts today Cap and rotor put them on.

Nothing!

Its trying to start but not
I've looked to see what the points are to be gapped at and the best I come up with is .016 to .019 can anyone tell me if this is right?

Now I notice that when I'm turning over the motor. The tach sometimes works and sometimes not. I think my ignition key switch is buggered up. Does anyone think this could cause the problems I'm experencing?
 
"Rick, at best, setting mechan

"Rick, at best, setting mechanical ignition contacts via a "gap" is an estimate ONLY of "Dwell".
The contact (points) "Dwell" is what you really want to be setting these to.
Your OEM Volvo Penta manual will have this information in it.
Setting a gap should be thought of as a place to start only. IMO.

Granted, a 4 cylinder ignition gives us a total of 45 degrees per cylinder for dwell to occur in.... but you are still better off using dwell meter for this.

."
 
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