Picked up a few engines and mixed in the bunch is this one.
Block casting #3733950
Head casting #3936850

No stampings on Dist pad.
Date code ends with a 9 meaning cast in 1959

No captains bars
No oil filter
The engine appears industrial with a base of yellow paint.
Has provision for a hand cranker on the front.

Any ideas? It does turn over.

Tom, the block casting number suggests a 54-55 block. Those blocks don't always have captains bars. Theses early 261 blocks can be bored larger then the later 261 blocks. Not a full flow, so can you confirm the smaller port for the smaller lines, like 235 size? The head is the common 86.2 cc 54-63 261 head. Has a 58-63 valve cover with the four attachment screws and center breather. But does not have the front 55-58 style motor mounts. Does not look like it has the later side mount bosses but I can’t really tell looking at the pass side of the block but maybe on the drivers side. If they are, they don’t look drilled but could be just filled with crud. Am I missing it or are there two bosses on the drivers side for a generator bracket? Early style style pre 55 water pump. So without taking it apart and looking for the steam vents and measuring the bore, looks outwardly like a 54 model year 261 but some of it is a mystery. Any chance it has the motor mount under the timing cover? Where did you find the casting date?

Wait, I see it. That is perplexing.
Mike

Very interesting find - lots of unusual characteristics on this one - that drivers side mounting bracket held down by two head bolts is quite beefy and right in the path of the normal routing for the generator belt.

Also, that woodruff-keyed snout extending beyond the crank pulley is more likely a PTO. The hand crank interface was a set of ears on the front of the balance-pulley:

when the engine fired those trailing 'ramps' would push the hand crank out of the snout (so the operator didn't get turned over by the running engine )

Great find! Can you imagine cranking a 261 ?

I was told that GM offered a sort of "crate motor" that was a 261 in the 54 water pump style that may show a later casting date. They had nothing stamped in the distributor pads. Warren Foster (wdoftexas) told me they were marketed as a direct replacement when the old 216s in the bigger trucks "expired" so they didn't have to change accessories to whatever. I think they were even painted yellow. May be one of those

That would answer a few questions, wouldn’t it. Learn something every day!

Took that fron hub off and it is machined to fit perfectly to the balancer.
Underneath it there was a flathead allen screw securing the balancer.

I have a 41 Chevy truck with a 216, Might just put this in and add a simple turbo to it.

Weird to see this was cast in 1959, and still uses the bypass filter system.

I will follow along if you do put a turbo on. I have kicked that around for a while. I am just completely lacking in knowledge.

Curious indeed. In a standard car/truck installation the fan blades run very close to the radiator core . . . with that hub installed that snout would protrude through the radiator core (let alone the pulley or gear that is to run on it).

Has to be an agricultural/industrial application with the radiator situated higher - or with more clearance and a shroud. Perhaps a big truck as suggested but with the heater hose outlets plugged a road-going application seems unlikely.

That three bolt mounting flange (attached via two head bolts) is in play here. What's it for? Why are the standard generator mounting holes apparently unused?

I have always been impressed with how much work was done by 216s, 221 Dodge flat head sixes , and Ford Flat Head V8s. Bigger engines came along but late 30s to mid 50s they were the work horses along with some IH sixes both flat an OHV designs. They were worked hard!

All right. I took some measurements of the 41 engine bay with 216. Also measurements with a 301 pontiac turbo bolted on the 261.

I had made a intake adaptor a while back and this is where it will be used.
The turbo setup stick out from valve cover side about 13.5" and the air cleaner flange ends up about 6" above the valve cover.

After the same measurements on the 41 it looks like it all will fit with comfort.

I saw that truck at the open house. That turbo will be great. Please show pictures of the tear down. I have to ask, does the snow ever melt there? Lol. Jay

If Greg_H54 is right about the sort of replacement crate motor, using the small lines and early water pump makes perfect sense. You get a 261 and swap all of the accessories, including the oil filter if the original motor had one.

And just as an fyi, Pontiac of Canada used 261 motors as their base motors in those years and they used small lines. I have 2 59 Canadian Pontiac 261 blocks, one in my 57 chevy. Both use the smaller lines.

That does make sense especially with the short water pump and the front mount. It will bolt right in where the 216 was without having to move the radiator. If you have to move the radiator you may as well go with a 270 or 302.
In the '60s I put a 261 in a '40 Chevy pickup. It had a Corvette intake with 3 carbs. I don't remember the exact issue but the left front hood latch would not quite close. Those were long side drafts and I don't remember what air cleaners I was using. It was the fastest street light to streetlight car I have ever owned. Highway? Not so much. I don't remember moving the radiator on that one. Maybe it was one of these engines or maybe it had a 235 in it when I got it.