Volvo sp275 swap to a dou prop

kimcrwbr1 said:

Do you have pics? The guys need to properly ID your drive to give you better info.

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japato11 said:

Hi
I would like some or any advice


I have a gm v8 260b engine in a 24' 1986. 2450 BAYLINER with Volvo 275 sp out drive with a ratio 1.61 I would like to change the lower unit to a 280 290 duel prop can anyone help me try do do this. There are some dou prop lower units for sale on eBay .
i don't know which one can work with mine drive.
Your 275 is among the AQ series. You can use any of the correct ratio AQ series Duo Prop lower units for gasoline engines.



I called Volvo and they said it can be done but there is a lot of different ratios that need to be changed
Not true!
In the AQ series gasoline line up, there are only three ratios....... 2.30:1, 1.95:1 and 1.78:1.
Your engine requires the 1.95:1.


I don't know much on ratios and don't know were to start
The over-all ratio will be stamped into the prop shaft bearing carrier just ahead of the ring anode location.
Have your seller show you this number.
Props and ring anode must be removed in order to expose this number.


i have already rebuilt the upper drive because of leaking seals. So I know about enough to do this type of work . I just need some directions to get it going

I READ ALOT OF FORMS ON THIS BUT COULD NOT FIND ANYTHING ABOUT HOW THE RAIOES WORK IN THE DRIVE WHAT THE PRELOAD TEST NEEDS TO BE. DOES ANYONE HAVE A STEP BY STEP INSTRUCTIONS TO DO THIS
It will be lined out in the Volvo Penta OEM work shop manual.
You will be taking the A and B dimensions, and then doing some math as to determine the NEW shim pack value.
If you are NOT comfortable doing this, hire a professional who is.

If you use a C or later Duo Prop lower unit, the lower unit vertical shaft will be shorter.
The vertical shaft spline coupler must be the long coupler for the C ...... not the short coupler that you'll now have!


will I need to change anything else Or just GET A D/P lower unit WITH the correct type of RATIO
Gear oil will no longer be 30W engine oil.
It will now become GL-5.

thank you. Japato11

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RicardoMarine said:

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