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This was brought to my attention in a different forum for a different car...apparently the MG guys are using them as well.

Stock 190hp/275 ft/lbs four cylinder. Aluminum block, 460 Ford cylinder head/rods/pistons, Chevy small block bellhousing and motor mount bolt pattern. It would be a nice upgrade for the 2.5 Astro/Safari....oh, wait, that's still 30hp and 40 ft/lbs more than a Z-code 4.3....

Say hello to the Mercruiser 470 3.7l! With an aluminum Kaase P51 429/460 head...probably more than 190 hp/275 tq.

 

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Used motors can be found under $1k. The aluminum heads are I think $2600 for a pair...but you only need one!

 

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Cheap (ish....), different, lighter, more room, and did I say different?

 

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Well, one thing is it's not an MG motor...I don't think a 1275 or 1500 would be enough to pull the doghouse off, much less move the whole van! Some info just happen to come from an MG site.

Like I said, stock form is more power than a stock Z code 4.3. Way more power than a 2.5 Astro. So, if you have a rare 2.5 5 speed, you could exceed the power of a 4.3 and still get to keep your weird 4 cylinder van a weird 4 cylinder van. It's not always about ultimate power and slapping a V8 in everything (I'm not dissing the v8, I do have some v8 mounts waiting for the day I decide I actually want to do that).

I just think this is a cool little motor with some real potential for hotrodding. And it sure looks pretty all polished up. Maybe an S10...

 

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All good points, I don't disagree! But I think you are missing the point of this thread....not everyone is looking for tire shredding power.
This is a potential answer for a question no one is really asking! Some people like to do things a little different. As evidenced by the polished motor sitting in the 30s Ford frame in the pics. Sure a v8 is an obvious answer, but he didn't want that answer.
Some people really like "WTF?!" reaction. That's part of the fun.
And again, it's not some little 4 cylinder farty thing, it's 224ci that makes more power stock than the 2.5 or 4.3 Z in the Astros.

 

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Do you have a link to that article where you got the photos?

Here is one thread, but i dont think it's the one with the photos.

https://www.jalopyjournal.com/forum/threads/big-inch-four-mercruiser-470-485.289260/

 

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Here's a new one...
340-HP 3.6-Liter Four-Cylinder LS-Headed Crate Engine

"In an industrial application, this small package, at only 1,800 rpm, will put out diesel-like torque numbers. If configured for a performance application, this bore and stroke combination could produce well over 300 horsepower and nearly 500 lb-ft of torque!"


Blueprint’s New LS-Headed Four-Cylinder Crate Engine Prototype

 

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That motor might be a good swap for my 2.5L Fiero. Dressed up that way it would look great in there.
View attachment 288907

It might be kind of big for that. Tricky to mate to the transaxle. Is there a SBC adapter for the Fiero transaxle?

 

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I just ran across the 3.6 article. I'm sure it would be pricey. What makes it interesting is that even though the current generation narrow angle GM v6 is a powerhouse compared to the 54* and 60* v6's of just 15 years ago, this 4 cyl industrial motor is capable of more power than many of the old 'musclecars' that are so revered.

Talk about whatever you want, it's my thread and I see no reason to limit the discussion. I like oddball and nothing struck me as more oddball than a 4 cyl (normally a reason to NEED a swap) that makes as much or more power as the V6 it could replace.

Not sure practicality is a good criteria for most non-stock motor swaps, some just go easier than others. And none of these are really good options if changing out a stock motor is going to be a struggle. The 3.6 will require some headscratching. Since it's not a car motor, it may be easier to convert to carb than even an LS type V8, but without more info...?
The 3.7 boat motor, on the other hand, has a few issues (bellhousing is not exactly a straight bolt up but it's minor, adapting a regular alternator, dropping compression, etc.) but is already a carb motor (4v quadrajet) and the distributor is related to the 4 cyl from the Chevy ll, I think. Still, it requires work to fit it.

Hotrodding the 4.3 is, as you say, the most economical. With fitting in a same year V8 with stock style TBI (or CPI?) being the next cheapest and practical. I think MMusicmans carbed V8 might cost a little more due to buying a new 4v/headers/HEI.

As for finding a mechanic, most seem to want easy repair work. That doesn't seem to include 20-30 year old crusty vans with brittle plastic. Geez, the last mechanic I went to with the van, just to mount tires I bought, they damaged my rockers with the two post lift.
A rebuild shop, if the 4.3 is beyond them, why would you trust them with anything?

 

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4 are fine, if the car is the right size for it. Like my Opels. A 2.5 in an Astro? Really?