Volvo Penta Duo prop Identification

[AKveps]

Hi all,

This is my first post with my first big boat so please excuse me on any breaches of etiquette...


I am looking for information on the engine and out drive on this boat I purchased.

For help in identifying the drive the boat is a 1981 Bayliner 2755 Sunbridge

The engine has been recently rebuilt and does not have any original tags on it
Its a GM block and I was told it was a 350

The outdrive does not have any marks I can see on it or any riveted ID plates
The props that came off of it are B3 based on their marks
I cant see any marking identifying the gear ratio behind the props

On the bell housing under the trim pump there is a volvo tag with the following information:
PN 850678 7913
Serial NR 621888

Volvo USA says they need 10 digits to identify the drive, so they were not able to help with this information.

Thats all I have...

If anyone has information that can help me identify both the engine and drive train it would be appreciated.
I know nothing about this setup, so any assistance would be great.

Pictures of the outdrive and Volvo ID plate are below:

Thanks for the help

 

[Don S]

Re: Volvo Penta Duo prop Identification

That drive is an assortment of parts. The transom shield and intermediate section of the drive is a 280. The upper gear box is an early SP due to the top cap shape, and the fact that on newer versions of the SP upper, they had different bearings and wouldn't fit your 280 intermediate housing. Probably explains the lack of the back cover as well since the original cover wouldn't fit with that upper.
Since it's a 1981 boat, the single prop lower unit was replaced/upgraded to the DP lower. Did that on my 280 as well. The DuoProp drives didn't hit the market until 83, and only on diesels. They didn't show up on gas engines until 86.

Also, that serial number is for the transom shield assembly, not the outdrive. There should be a tag on the upper gear box just in front of the top cap.

 

[AKveps]

Re: Volvo Penta Duo prop Identification

 

[AKveps]

Re: Volvo Penta Duo prop Identification

Thanks for the reply Don S,

I removed the cover just prior to taking the picture in hopes it would help identification.
I went over the upper gear box and couldn't find a tag anywhere on it. Could it be stamped information on the cowling? The paint on it would obscure that. Are there any other features that would identify it further?
If I don't have the serial number, am I missing anything important (such as special tolerances) or can it all be gleaned from the pictures?

Is there a good set of manuals for understanding this drive better? Because its a mix and match, where should I start with manuals for this beast?

More pictures below of the outdrive are in the last post. Editing my post didnt seem to work ...

 

[AKveps]

Re: Volvo Penta Duo prop Identification

Found the Tag!

Unfortunately its so badly worn its pretty well useless. I pulled it off and cleaned up the backside
The serial number is ??02059007
On the tag was also stamped "SP A" (Bang on Don...)

The picture below is of the backside of the plate (the front was worn away). Reverse image

Can the partial serial number help any?

 

[Don S]

Re: Volvo Penta Duo prop Identification

SP-A is all you need for ID of the upper gear box. The SP-A was the only version of the angled cap and back cover that would fit on the older style intermediate housing. Plus you can't use the SP-A style intermediate housing on a 280 transom shield. The DP lower can be used on any of the 270 and newer drives of that style.

What exactly are you looking for?

 

[AKveps]

Re: Volvo Penta Duo prop Identification

Thanks again Don,
I would like to go through the drive and make sure everything is in good working order, so I was just looking for the information on what is was. From there I am looking for a set of manuals or online instructions for removing the drive and checking it over.

So are you saying that this setup is an SP-A with a 280 or a 270?