Mercruiser to Volvo conversion

[erikgreen]

Hey, all;

I have an opportunity to buy a complete Volvo Penta AQ270DP drive system to replace my Mercruiser Pre-Alpha drive/transom system, and I need to know what would be involved in converting if I went to the VP.

The Mercruiser works ok, although the lower unit is on its last legs even after last year's repairs. This VP would be cheaper then a new lower unit from SEI for the Mercruiser. Unless it needs repairs I'd just have to buy a set of DP props (expensive, yes).

The VP comes with "everything but the engine" which I believe is a cracked block. Not sure yet if the guy wants me to haul the whole boat away or what, I'm hoping so.

The drive is from a boat which had a 5.7L engine, so the gearing should be right for my GM 350 - seller says it's 1.95 to 1.

My question is: Is it possible to use this drive system with my 1981 GM 350 engine? I know switching years in the Mercruiser drives is problematic due to bell housing size, etc. I don't know what engines Volvo paired with this drive system. I'm going to ask what engine it was attached to.

What are the gotchas in trying to use this drive with my existing engine? I don't know year or serial on the drive yet, I'll get that when I can. But I'll have to move quick because this is a rather low price for this VP.

Right now reworking the boat itself isn't a problem because I'm doing that anyway, so a new transom hole, engine mounts, etc aren't any extra work.

Thanks,
Erik

 

[Don S]

Re: Mercruiser to Volvo conversion

Depends a lot on what you consider complete. You are going to need the Y pipe and the engine bellhousing and flex plate in order to attach the engine to the transom shiield. You are also going to need Volvo exhaust manifolds and risers and hoses to match up to the exhaust Y. The 1.95 gear ratio is the proper one for a DP outdrive and a 350. You are also going to need a raw water pump to mount on the front of the crankshaft pulley. NAPA carries them, very common.
The hole in the transom will have to be enlarged from the Merc, Volvo still has the paper templates for the cutout I believe. I also have the .pdf version, but it's hard to tape to the transom.
You MIGHT get away with the Merc controller, not sure about that, but you will need a different type of shift cable.

 

[erikgreen]

Re: Mercruiser to Volvo conversion

Okay, sounds doable then provided I get all the parts I need.

I think I might be able to get the whole boat this guy has, which would give me everything including the old engine, manifolds, etc.

Right now I have an aftermarket control, I think it's a teleflex, with the original mercruiser cables. I wouldn't mind replacing those.

I'm going to go forward with this and see if it turns out to be as good a deal as it looks... I wouldn't mind a dual prop, nor the more solid volvo drive system.

Erik

 

[Don S]

Re: Mercruiser to Volvo conversion

With the whole boat, you could actually make a template from the cutout already there.

 

[erikgreen]

Re: Mercruiser to Volvo conversion

Why go halfway?

I could just take a sawzall to the second boat's transom and use that cutout piece as my template

 

[Don S]

Re: Mercruiser to Volvo conversion

It's probably rotten, and why he wants rid of it.

 

[180shabah]

Re: Mercruiser to Volvo conversion

It's probably rotten, and why he wants rid of it.

Only has to be strong enough to support a pencil....

 

[Don S]

Re: Mercruiser to Volvo conversion

Why go halfway?

I could just take a sawzall to the second boat's transom and use that cutout piece as my template

DUH, I though it said TRANSOM, not TEMPLATE :redface:

 

[mtnrat]

Re: Mercruiser to Volvo conversion

Oh yea. If it is all there, do it!

 

[martyh]

Re: Mercruiser to Volvo conversion

Are the AQ drive bolt patterns the same as the newer SX/DP drives?

 

[stroyer]

Re: Mercruiser to Volvo conversion

I have made a conversion template from alpha to Volvo DP290A
It bolts in the old Alpha holes (the red ones) and ensures that the centerline is correct.

 

[erikgreen]

Re: Mercruiser to Volvo conversion

Are the AQ drive bolt patterns the same as the newer SX/DP drives?

And along these same lines, how compatible are older Volvo transoms vs. newer ones?

The DP drive I talked about above turned out to be only the lower unit, while I need the whole system (the seller can't read well, apparently.. I asked him twice if it was the whole drive train (twit).

But I found an old boat with an AQ200 drive, and this time I've made sure it's the entire drive system (and boat). It's a 4 cylinder engine, though.

Any chance I could get that (it's cheap) and use the transom parts for anything? I'd rather not mix and match models/years, but if a number of the parts are the same I could save cash getting an older/cheaper model, and I could sell off the lower unit with the wrong gears (or can they be changed?)

Or is my best bet to find a boat with a complete v8 drive minus engine in the spring? Improper winterization could be my friend

Erik

 

[Don S]

Re: Mercruiser to Volvo conversion

I wouldn't go with anything older than a 270, even that is pushing it. lots of the parts aren't available for the 200 and older drives, and used parts are almost non existant. And trust me, fixing your Merc is going to be a lot cheaper in the long run than converting over to an antique Volvo drive.

 

[erikgreen]

Re: Mercruiser to Volvo conversion

Cheaper, yes, but I have decided I'd like the Volvo solidity and reliability if I can get it. I'll keep looking for something newer, but if I can't find anything maybe I'll just look at upgrading some of the MC parts... maybe I can overhaul my old transom and have it leak less

Erik

 

[Don S]

Re: Mercruiser to Volvo conversion

While you are looking, keep the SX/DP-S drive systems in mind too. They were used from 93 and up. They use the same exact cutout as the Mercruisers use. Even if you found an older OMC Cobra transom shield, inner transom shield, flywheel covers etc, you could use them, and by changine the bellhousing on the transom shield use the Volvo type drives.
The insides of the SX and DP-S drives is the same basic stuff as the older 290 style drives.

 

[erikgreen]

Re: Mercruiser to Volvo conversion

Will do, thanks. That'll also let me extend my search past the time I cut the drive hole in my new transom

Erik