Looks very nice. 1975 Monte Carlo - cars & trucks - by owner - vehicle automotive sale (craigslist.org)
A 2bbl 350 was the standard engine in a 75 Monte, but a 4bbl 350 and 4bbl 400 were other small block options. ( that is not a big block so that rules out the 454 4bbl option) I am always amazed by how small a SBC looks under the hood of a 70-77 Monte Carlo. I also see the A/C compressor and all the brackets are missing. Nice looking example, but about $5-7K over priced IMO considering the inop A/C, base engine, bench seat, column shifter, and base interior.
I look at the fan shroud and think it's a V6. I've had two V8 Malibu's, a '78 and '79, and the only time I saw a shroud, that extended that far, was on a Malibu wagon with the 229 CID V6.
The add says 8 cylinder. I would go for the smallest v8 they offered. 350 most likely. Bet it’s angle distortion with the photo.
As Jeff says, no V6's at all offered on the '75 Monte Carlo. Engine is a 350, most probably a 2-barrel version, the standard version. I checked ALL the brochures for the 2nd-gen Monte Carlo, '73 - '77, and there was NEVER a 6-cylinder offered on them. The standard engine size was a 350 V8, up until the '76 model year, when it was downgraded to a 2-barrel 305 V8, except in California, which got a 4-barrel 350 standard there. When the downsized 3rd-gen Monte came out for the '78 model year, a V6 became standard.
Believe Vanguard Motor Sales had this car for sale back in 2019 and photo is below. Web address is locked. Miles listed then was 76,209 and engine stated as "350 Edelbrock 4 barrel". Just google 1975 Monte Carlo and Vanguard's sale video should come up among listings.
You have to keep in mind how far back in the chassis the engine sits in a 73-77 G-Body. That and the small size of a SBC makes for long fan shroud (and upper radiator hose ). With the larger Pontiac V8, the wider Olds V8, or the big block Buick's or Chevy's, the engine compartment looks more balanced and normal. But they still have long fan shrouds & upper radiator hoses!
I suppose it's just a matter of perspective. When I worked at Autocents in '98-'03, most of the clients had factory carbed engines. Of those, likely 40% were GM, and I'd say 70-75% of the GM cars and trucks were '70s vehicles. So it's fair to say, I've likely handled the majority of the GM sedans and coupes of the Malaise Era, and in those coupes, the Montes, the Cutlasses, the Regals, that had Chevrolet power, their shrouds were not that long with the V8's, only the V6s. But, I'm not a GM aficionado, so I haven't owned anything '70s GM in a very long time. My last GM sedan was the 2000 Century.
You may be thinking of the GM A-Bodies of the time, they were available in about the 75-77 time frame with the 231 Buck V6, but the engines actually sat about 2-3"s farther forward. Also I don't think Chevy offered a V6 until 78? in those cars. I found a 77 Malibu Brochure online that lists the 6 cylinder option as the old 250 CI 1bbl engine, so still an I6.
I'm trying to remember, I had a neighbor with a base Camaro, late '70s, it had the factory Chevy 229 V6, which apparently was really unpopular, and unusual as they usually had the 250 I-6. So, who knows? I do know that Chevy had 'short' waterpump engines, for tight compartments; without better pics, there's no way to know what this posted one really has. And, I looked at the engine pic abit more closely, it really looks like it has a V6 shroud AND radiator. But, that's just me. I'm not arguing that it has aV6, just that it's what it looks like, but the 229 was painted that aqua blue-green, and all the V8's were Chevrolet engine orange.
Looks like the same MC. According to the build sheet, it had the factory 350 2 barrel. Also, the bumper guards have been added.