f_inscreenname

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.

f_inscreenname

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

Katanna

iTrader: (1)

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

Fathead2

Fathead2

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!

Wobble

Agree

madbouyz

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 .

Fathead2

madbouyz

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.

Fathead2