What is this?
 

The older Donzi's had that bow life line and most were equipped with Fords and Volvo's.
That is my guess.

----No Donzi had a life line, but you may be thinking of a 27 Magnum Sport...….Bill S

Should be referenced to this thread https://www.offshoreonly.com/forums/...gnum-help.html so that 'newcomers' won't possibly be repeating previous talking points.
I am , however , beginning to think that it's a Mag 25 hull (only) copy .

Just out of curiosity , what is the spacing on those engine mounts ? That would be from outer stringer to center mount stringer/support. . To me it almost looks as though they're too close together for a V8 and might have supported in line 6s .

What magnum is this?
 

This boat featured is not a Magnum .25's were only built as a sedan.

26 Monza

flatt head
 

It is a 26 Monza.

Thank you Ed! Do you have any idea what year that is from? From what I can gather on the Monza's it seams like each boat may have had a different layout or deck, depending on what the customer wanted at the time? Im really interested in trying to figure out if the teak on this boat was original. Other than the few race pics I've seen, most of the photos and info from everyone shows a windshield of some sort. They also do not have any consistent brand labeling either? Thanks for the help guys, keep it coming!

So funny the difference between the Pleasure and the Race boats and yet were out of the same molds. My Nova is the same way. Pleasure boat looks like the top picture and the race looks like the bottom. Also funny 15 years later everyone wants small cockpit long deck boats. No longer did folks want the pleasure version of the boat that won on race day, they wanted the race boat version or one that looks like it.

IMO, dont buy an engine unless you hear it running, or know the person selling it..

When that thing was built the largest stock BB power was 330/454 , end even then it was probably more like 290 at the prop.
If it was me I'd do single BB power with the stoutest outdrive you can find . Treat the transom as though it's rotten and completely re-build it and then start from scratch with a clean , blank slate. Once you start seriously digging it'll probably turn out to be bad anyway.
One engine = good efficiency , less drag than 2 lower units and lower maintenance costs .
A single 'stock' BB motor in that thing with a B1 and you ought to see an easy 60 mph .

Parts for old volvo's are getting scarce - people who know how to rebuild/service are even more rare... Aside from a die hard historical buff who can appreciate the effort of rebuilding 100% original - your ROI, headaches and questionable reliability in the long run vs. a B1, leans to the Black drive especially if you plan on keeping the boat and running it often. Don't get me wrong - original is cool but the seasons are short and there is something about B1 parts/replacement in less than a week of downtime ...just IMHO

As MadBouyz eluded to with the 330/454 back in the day - a 350MAG has the same HP for comparison

Volvo Penta's are easy to work on. So easy that I even made a video.
The real question is if you have trim or not and if it important to you. Unless you have a rare Penta with Trim you are going to want to go with the Mercruiser. Don't confuse Tilt with Trim either. If it's not hydraulic you have Tilt only which is only used for raising the outdrive for trailering.

Way back when Merc used the Ford 351 block for some of their I/O packages. The bell housings were different than the ones used in the GM based engines , so I don't think that they're interchangeable in any way and thusly that would apply for the Volvo applications also .
From the pics you've supplied so far those are NOT trimmable Volvos. If you do have gauges that refer to the outdrive position they are more than likely the tilt/lift reference gauges.
As much as I love the simplicity and durability of the Volvos of that vintage you're going to knock yourself out trying to rejuvenate that drive system in this day and age when you could just do as I suggested above and do a modernish single BB setup that could give you north of 430hp at the prop. It won't disappoint and you'll have an engine room that you and mechanics will actually like working in .

Is there something specific I should look for that would indicate a trim function? Is the tilt mechanism hydraulic or electric?

As mentioned earlier , the pics you have posted show the non-trimmable 250-270 transom plate. No large 'elephant ear' trim mechanisms in sight . As a matter of fact you can clearly see the manual (and fixed) trim pins ! You mention these gauges for trim , can you put up a pic of them ? I'll bet anything that they're the standard tilt/lift indicator gauges.
The pin that actuates the tilt/lift mechanism is visible on the top of the transom plate just inside / above the steering helmet. When retracted it only looks like a large washer slightly protruding from underneath the transom plate. When activated it pushes down like an oversized nail and releases the locking mechanism allowing the unit to tilt up . It is purely an electrical device ( I believe a Bosch motor) and is not hydraulic at all.
Unfortunately you don't have any pics of the transom looking from front to back but if the tilt motors are still there they're on top of the inner transom assembly with a black plastic cover over them that's held on with a single top mounted screw .

Very curious . I can see that there's no internal steering arms as the boat has external hydraulic steering but all the pics are just cut short of where the tilt/lift motor should be visible. It ought to be on top of the silver colored shaft thingy coming off the top of the internal transom plate/housing. (And btw, they look to be in nice shape too)
I can't enlarge the pics of those gauges but they don't look like the OEM Volvo tilt gauges and of course the switch looks like it's long since gone kaboom so we can't use that as a reference. If memory serves me correctly the original Volvo lift/tilt switch was a simple single rubber boot encapsulated toggle switch. Up or down , nothing else.
Also interesting that as a 'performance' boat you believe that it had Ford V8s in it but it doesn't have through transom exhaust .

It would be interesting to see a picture with one of the outdrives lifted up and a look at this ram you're talking about as being at the bottom of the housing .
Now here's a what if.
Is there a chance that this boat was originally powered with Mercs and it was converted over to Volvos ? Two reasons I ask that . One , those gauges look like they could be very old Merc trim gauges and the thing you say is the remains of a switch could be an old Merc trim switch .
Two , the outdrives appear to have spacers on them to get the prop shaft deeper in the water . I can't recall ever seeing these before on Volvo units. Is it a possibility that it WAS once a Merc boat and the person re- rigging it just cut the bigger Volvo holes around the old Merc holes and then found the unit wasn't deep enough after the fact ?
Sorry to keep adding to the possible list of mysteries !

First thing I have to ask is, do you know the history of this boat and the way the thread started you do not. There is something special about this boat that is missing. Monza Marine (I had two 19 footers) did not do something like your boat for production boats. First I have never saw a drive extension for a Volvo Penta… ever. Also you have hydraulic trim of some kind (another special). More then likely home built also but to an insane level. That looks like a hydraulic ram form an old outboard in the top of the transom shield and I guarantee that it pushes down on the fork like the tilt motor would but on both sides. I had that same idea 20+ years ago but I was going to use a ram on each side to push on the fork being the mount was already cast into the shield so they can put the tilt motor on either side if needed. Then I found a Volvo 280T shield and there was no reason to do it anymore but at this point over the years I have seen about 7 or 8 different "homemade" trim set ups for Penta's. By far this is one of the cleanest versions. More then likely runs off a MerCruiser trim pump. I would love to see how it makes contact with the fork. Another thing I just noticed when I blew up you pixs, your shield has no trim pin holes except for one. They don't come that way, at all. There is something very special about those drives. And you don't put special drives on run of the mill boats. I'm starting to think these were Volvo's factory mods. I would start looking for Monza race boats with a Volvo sponsorship. Those drive alone could be worth more then the boat. You also need to find out what ratio they are.
Last you need to decide if you want an original or a retro mod boat. Personally I would already stay with the history if possible. No matter what you do short of slapping a couple nascar motors in there with a couple Bravo's speed is going to be about the same. A massive BB or 2 small blocks speed wont be that different. Now those drive look like they can handle insane power and if they are 1.36 drives you will need massive power to push them. Today a couple LS motors would make that boat scream. All you would need is a bellhousing (found on eBay) to hook them right up to the drives.
This my 280T transom shield with a 270 drive with Volvo 250 (1.36 to 1) gears.

https://cimg4.ibsrv.net/gimg/www.off...7c3d578005.jpg

I took this picture decades ago. Kind of has the same lines but a bit newer.

https://cimg7.ibsrv.net/gimg/www.off...ad5d4dd753.jpg

In the first picture behind the green arrow, that appears to be mechanical trim indicators of that era.

Thank you for all your input. I’ll have to take more pics of the drives and try and do some more research. I did think it was strange that the top of the mounts went all the way into the style line on the transom. Although, there’s not too much more room in the bilge to lower the motors much, either.

I have no idea what those two cables on the plate do on the teak dash deck. I have not pulled apart any of the steering hydraulics or shift and throttle cables yet. They are very similar to a mechanical shift/throttle cable under th helm, but then get lost in the mess.

Since I’ve had so many unknowns of where it’s been or where it’s going, I’ve been slowly taking everything apart manually, rather than a sawzall and grinder. I guess for now, in terms of power, mercruisers would be easy to find and install. I guess the biggest question would be what and where do I look for something that would mate up to these Volvo’s if that becomes the path? Are there bell housings available to swap different power, or should I positively identify the ones I have, then power from there?

Thanks again for all the info and help!

Agree

Aye. And no doubt for the missing trim tabs. But if it's the tab switch that's right under the indicators IMO that's kind of a strange place to put it seeing it's quite a reach over that grab bar.
Can't see anywhere on the transom though where the cables would have gone through so along with the awfully filled in exhaust outlets someone's done a lot of chopping and changing on this boat. And that style line on the transom surely can't be original . No one would have built a boat with that knowing that the transom plates would have to go over/on it.

And if you're going to get some more pics lift up one of those outdrives (just reach behind and unlatch the locking device and then lift) and get some clear shots of the mystery trim mechanisms .

From what the pics so far show I'm 99% certain that that's a Magnum 25 splash ( I do have one , after all) . Back when splashes were popular the law was that the splash had to be at least 10% different than the original to avoid copyright infringement. That ridge across the transom could have been one of the alterations made to meet the regulations if it is an original build.
Incidentally , we powered ours with a single 502 after the total rebuild so that's why I can say with a degree of confidence that a large single BB installation would work well.