If you read Curbside Classic, it’s likely that you have subscribed to at least one or two of the big automotive periodicals, and it’s just as likely that you know that print journalism is sounding a lot like the last minute of Charles Mingus’s “Pithecanthropus Erectus.” (For those who hate jazz, it’s an interpretation of mankind in its death throes.) Needlessly obscure analogies aside, after a lifetime of dealing with stacks of car magazines in my living room, I’m down to only two, and one of them is Hemmings Motor News, which I get because Hemmings Classic Car (sadly) closed its doors with well over a year remaining on my subscription. Hemmings still reports on auctions, and one of the cars at the 2025 “Throttle Car Club” auction in Maine had such an unusual powertrain that I’ve spent hours poring through my materials trying to learn more. Unfortunately, this seems to be a combination that nobody cares that much about.
This is the actual auction car, which was a “no sale” with a $9,000 high bid; apparently, the car was not an exceptional example. Hemmings reported that the Delta 88 had a “Pontiac-built 400-cu.in V8, one of three engine options for ’75.” My primary reference tool for such matters is Krause Publications’ Standard Catalog of Oldsmobile 1897-1997; while it’s not perfect, it is mostly accurate and has easy-to-read tables for production numbers and engine options. It mentions that “of 7,181 Delta 88 Royale convertibles built [in 1975], 245 had a 400-cid V8.” They don’t mention what division built it, and its specifications are not listed in the table. Most Oldsmobile fans know that the Olds 400 was no longer used or needed after 1969, as General Motors lifted its cubic-inch limitations on intermediate cars; therefore, Hemmings must be right about the Pontiac, as the only other 400 in the GM line in 1975 was the Chevy small block. Still, 245 cars? Its rarity is obviously not a selling point, but what about Oldsmobile using a Pontiac engine in 1975?
Most of us know that General Motors divisions had shared engines before 1975, but those were mostly base six-cylinder engines: Pontiac and Oldsmobile used a Chevy six back in the ’60s, and Oldsmobile used the Buick V6 as well. We also know that GM’s engine consolidation programs of the later ’70s created some truly interesting hybrids, and even a lawsuit when a man discovered that his Oldsmobile didn’t have the “Rocket” V8 he expected, but rather an “inferior” Chevy 350. In those days, Oldsmobile sold quite a few of its engines to other divisions, and Pontiac sold Iron Dukes and 301s to other divisions with some regularity, too. But for some reason, it was extremely rare (and almost unheard of) for another division to buy a Pontiac 350 or 400. Whether that was cost, quality, or something else, I don’t know, but I can’t think of another non-Pontiac with a Pontiac 400 under the hood. But what 400 did Oldsmobile use in it’s end-of-the-line-for-a-while ’75 convertible?
I’m sure that those with Oldsmobile connections back in the ’70s would know right away, but the information I’ve found is inconsistent. The brochure lists a “400 V8 2-bbl. engine” as an option for the Delta 88.
A four-barrel 400 was listed as an option for the 98 and 98 Regency in the catalog for the 1975 Oldsmobiles.
This Oldsmobile Parts Manual from 1979, however, only lists an “L48” 400 four barrel as an option for the Delta 88. Pontiac’s brochure (and my Standard Catalog of Pontiac), however, does list a 400 two barrel as the standard engine in the Catalina, and the Standard Catalog says that it is an “R-Code” engine producing 170 horsepower with a 7.6:1 compression ratio. I assume that that is the engine in the featured convertible.
I couldn’t let that stand, however, without consulting my service manuals in the garage. Aside from my daily driver, I don’t own anything newer than a 1974 model, but I do have Chilton and Motor Manuals from 1976 and 1978 respectively. This chart came from the Chilton manual. It lists a 180-horsepower 400, ten more than the R-Code two-barrel.
On a preceding page, however, it lists a 400 that clearly has the Pontiac’s 4.12″ bore and 3.75″ stroke, but it is a 190-horsepower four-barrel engine. Perhaps that’s the engine that was available in the 98 and 98 Regency. Pontiac’s own L78 400 four barrel was rated at 185 horsepower, so Chilton clearly has some inconsistent information.
Oddly enough, the Pontiac entries in the same manual show a 175-horsepower 400 two barrel and a 200-horsepower 400 four barrel. So much for editing.
The 1978 Motor manual lists a 190 horsepower 400 four barrel in the Oldsmobile section, but no two barrel at all.
The Pontiac chapter, however, does list a 170-horsepower 400 two barrel for 1975.
If I were at trivia night at the local pub and I had to write an answer down because the emcee was bearing down on us to collect the slips, I’d say that this Delta 88 Royale most likely has the R-Code 170-horsepower Pontiac 400, regardless of the wildly inconsistent information I’ve found. It’s sad that this car has such a rare engine combination that such misinformation is all one can expect, but perhaps a reader has a 1975 factory service manual on a dusty bookshelf that can help us verify this strange engine combination and put the basics of horsepower and carburetion to bed for good. Or maybe someone was working in the parts department at the time and was flummoxed by the 88 with a Pontiac 400 and had to figure it out in the books.
Was there another instance where a Pontiac 350 or 400 found its way under the hood of a competing General Motors make? Those early years of the GM engine program consolidation are fascinating, and in a way, this Oldsmobile is the forerunner of them all. It’s too bad that it may also be the most obscure.
Related CC reading:
In Motion Outtake: 1975 Oldsmobile Delta 88 Royale Convertible – Blue Razzamatazz
Can;t say about the 350 or 400, but some GMC trucks used Pontiac engines, late 50s.
That guy with the Chevy 350 in his Olds started quite a row in the early 70s. I subscribed to Motor Trend then, and MT followed that story. They even published a piece on how to visually identify the Olds vs Chevy 350s, so people could tell which their car had. iirc, GM’s defense was that Olds could not build enough 350s to meet demand, so they supplanted the supply with the Chevy.. After the suit, GM brochures started printing a tiny disclaimer that their cars contained engines built by various division. From my perspective, I did not understand why GM spent the money to have each division designing it’s own engines. Seemed wasteful to me. A Ford 351 Windsor was a 351 Windsor, regardless whether installed in a Ford or a Merc. Same with a Mopar 383.
VOLUME, “our commercials are louder than anyone else’s” But seriously the difference was volume, GM had ~50% market share for a long time which meant they needed a lot of engines. Back in the 50’s and early 60’s each division had a lot of autonomy and their own factories. Since BOP and Cadillac were mid and upper priced brands engine differentiation was important and they had unique displacements. As time wore on GM finally figured that they should focus more on competing with other mfgs instead of having their brands compete against each other. Add in some edicts from above and the displacements converged, at least as advertised.
What didn’t change however was the need for a lot of engines which meant a lot of engine lines were needed. So despite the fact that they all sold 350’s they still needed multiple engine lines and it didn’t make sense to add more lines for the same engine when they had lines with unique engines already up and running. Far cheaper to adjust the tooling and make a few new/modified castings to make BOP 350’s instead of new from scratch Chevy 350 lines.
The fact was GM was caught a bit off-guard by the success of the Cutlass in the wake of the energy crisis I. Meanwhile sales of the full size Chevy fell significantly. That meant lots of Olds needed engines and their engine line was never designed for the type of volume they were experiencing.
Ford did do something similar with the FE destined for Fords and low line Edsels and the MEL for high line Edsels, Mercuries and Lincolns. Back in the days of the Flathead there were also unique versions for the Mercury and Ford.
The difference was (from what I understand) that Ford’s divisions did not have their own engineering departments like GM did, at least for engines, so the FE and MEL engines being offered only in some divisions was a marketing decision – different from GM where each division had their own engineering staff designing and building their own engines (and sometimes, their own transmissions).
GM did have an odd setup where if one division needed an engine produced by another division, they had to actually buy engines from them. Something needed to be done about this, though that something wasn’t Roger Smith’s 1984 reorganization that centralized engineering and left the divisions only as marketing arms, making the divisions’ offerings too much alike.
I tend to think that each division with it’s own engines helped give exclusivity to the brand. And years ago, both Ford and Chrysler had divisional engines as well.
As time went on, Ford and Chrysler standardized to corporate engines and GM eventually too. I attribute all the standardization and badge engineering to the costs associated with government regulatory compliance which has driven the cost of vehicles out of sight. There certainly is no brand exclusivity any more within any automotive corporate structure.
Brand differentiation was a main point; with in-house engines, each brand could reinforce the image of having a unique character (Cadillac had, for example, the largest displacements). To use a modern term, engines were a unique selling proposition of each brand
In general, the GM divisions had a lot of autonomy in doing things their way, and I believe there was also strong internal competition between them.
Whether or not this was good is perhaps debatable; competition spurs innovation, and at some point that innovation would trickle down to other divisions of the group.
Yet one could argue that the distance between the various divisions and doing things “their way” contributed to the disaster of the X cars and GM’s reorganization of the 1980s, which pushed hard against an internal organization that could not accept drastic changes so fast.
Certainly it is an interesting topic to discuss
And that Delta 88 is beautiful!
No relation to the engine, but is the available air cushion restraint system an airbag?
Yes it was:
https://www.autoweek.com/car-life/a34892691/the-gm-airbags-of-the-swingin-70s/
Tks!
I think you nailed it. Chevrolet’s 1975 400 CI V8 engine was only manufactured in four-barrel carburetor form (175 net HP), Olds, as you pointed out, and Buick were out of the 400 CI biz, and Cadillac never produced one. That leaves Pontiac as the obvious suspect.
JO
Definitely a new one on me as I’ve never heard of or seen anything but the 301 being installed from the factory in a Olds or Buick. I guess Olds decided they needed an engine to fill the gap between the 350 and 455, didn’t have one in house anymore so Pontiac was the only choice other than Chevy and since they had to go hat in hand to get the 350’s they needed I guess they rung up PMD. I can also see the powertrain engineers having an aversion to the siamese bores of the Chevy 400.
Interesting, I never heard of a Poncho 400 in an Olds.
I also got rid of my piles of old car mags and am left with Hemmings sales catalogs, which will be gone when the subscription runs out.
BTW, am glad to see curbside back in business. They were gone for 2 days!
What’s curious is that the 1975 brochure that is online at oldcarbrochures.com does not show the 400 as an option. Brochures were commonly updated throughout the year. I suspect that the 400 may have been available at the beginning of the year but then dropped, which would likely explain the very low number installed.
Interestingly, the Olds 1975 brochure on lov2xlr8.no does show the Delta 88 and the 88 Royale with an available 400 2BBL
The page on the Delta is almost the same on both brochures – the only difference I can spot is in the equipment.
Unfortunately there does not seem to be a printing or revision date on either document
GM is almost alone among major manufacturers in not assigning catalog/part numbers or dates for the majority of their brochures. As a collector, it drives me mad. In addition to revisions, some brochures were offered in different sizes but otherwise looked identical. When searching for a specific brochure on eBay, the part number is often the only way to identify the right one. Most sellers don’t list the number but can find it with some instruction.
the brochure at oldcarbrochures.org also has the 400 v8 with 2 bbl shown as optional. The 98 also offers a 400 with 4bbl.
I believe it was sometime in the early 1970s when smog mandates required the costly certification of each individual powertrain. I’m guessing that someone at GM Corporate saw how much they were paying to certify so many overlapping engines. At the same time, demand for V-8 cars was dropping.
I’m just spitballing here, but I’d guess that in 1970, something like 70-75% of car sales in the US included a V-8. Yes, some folks of lesser means got straight sixes, and there were handfuls of 4-cylinder cars sold at various import brands, but most Americans wanted and bought a V-8. By 1975, however, those numbers were dropping. I’d bet the percentage of cars sold with a V-8 were falling fast, mostly due to the Oil Crisis of 1973. GM engine plants started to run at less than maximum capacity, which allowed them to phase out certain overlapping engines.
When I was a kid during this era, any car without a V-8 was considered cheap and unwanted. An inline six was barely passable but a “four banger” was definitely an object of ridicule.
When CAFE and emission laws came into effect, both GM and Ford went into their dreadful “small V-8s” like the insipid Olds 260 V-8. It was actually slower than the V-6 but at least it felt and sounded like a V-8 some of the time.
That car is a rare example of GM’s engine swapping, I have never seen a Oldsmobile with a Pontiac V-8 in it. Ironically in 1977 the new Olds 403 ‘small block’ (low deck) V-8 was introduced and wound up powering a lot of Pontiacs, including more than a few Trans Ams.
Oldsmobile V8s made the rounds in all the divisions, didn’t they?
Probably the strangest part of the whole Pontiac-in-an-Oldsmobile situation is that they really didn’t seem to need it; their own 350 four barrel had similar power numbers, leading me to believe that this must have been an engine shortage issue. One of the websites I read while I was doing research on this car mentioned that there was an engine shortage near the end of the model year, so Oldsmobile had to buy some engines from Pontiac. I don’t know if that’s true or not because I wasn’t able to verify it anywhere else, but I imagine that that would have led to some long nights for some engineers and plant managers.
Sometimes it was an engine shortage issue, other times it was because one division’s engine didn’t meet California pollution regs but another division’s engine of the same size did.
Good point, but I doubt the Pontiac fell into the latter category in this case. Now THAT would be something to look into: Which of General Motors’s engines was the cleanest during that time period?
I would surmise that the last ones to be dropped were the cleanest.. Pontiac, Buick and traditional Cadillac went away first, the Olds stuck around until 1990, in carbed form yet. The SBC was the last soldier, giving way to the LS.
Another way to infer it is to check the period brochures and see which one weren’t available in California.
As an example late 70s Firebirds. Pontiac power personal not grata, Olds okay.
Having driven a 455 1976 Custom Cruiser, I couldn’t see that car with anything less. The car was a horrendous sluggard as it was.
Major props for “horrendous sluggard”.
The Pontiac engine shares the same bellhousing pattern as the Olds engine so it would make sense to use the Pontiac engines if they needed a quick replacement/substitution.
All the BOP engines do, as well as Cadillac I think.
In the 90s when I had 4 magazine subscriptions GM usually had two cars among the 4 or 5 tested with the same GM motor in their two cars. Of course the reviewers praised the imports and the GM products came in last. Part of the downfall of GM was giving up division motors and transmissions. A lot of car buyers wanted a motor unique to that division. I can see the need for standard motors with falling sales, but that led to the demise of the old GM.
Nice Olds regardless of the engine “maker”.
Aren’t there numbers on the engines that can be traced?
Makes me wonder, if a Pontiac engine is put into an Olds at the factory, would its numbers show Pontiac, or would any engine numbering be addressed/adjusted to say it’s “an Olds now”?
(Or does it not work that way?)
Setting the Pace: Oldsmobile’s First 100 years, by Helen Jones Earley and James Walkinshaw, which is Oldsmobile’s official history, lists the 170-hp 400-2V as the L65, for the 1975 Delta 88, and the 185-hp 400-4V as the L48, for the 1975 Custom Cruiser and Ninety-Eight. The 1975 Automotive News almanac doesn’t list the former, but it does list the latter, with ratings of 185 hp and 310 lb-ft. The 1975 Automotive Industries spec tables don’t list either.
The EPA issued mileage ratings for the 400 in both the Ninety-Eight and later the Delta 88: https://afdc.energy.gov/files/pdfs/1975_feg.pdf — the Delta 88 was apparently added to the second edition, not the first edition, which suggests a mid-year addition. That would also explain why the L65 400-2V engine is in some contemporary brochures and specifications lists and not others.
Automotive News for August 26, 1974 (just before the beginning of the model year) said that the 400-4V would be optional for the Ninety-Eight and Custom Cruiser, but doesn’t mention the Delta 88.
I have that book, but I have no idea where it is! Ouch, the 400 two barrel had worse fuel mileage than the Olds 455.
Because the use of the 400 was only for one year and because the 400-2V was apparently a late introduction, I think this was very likely an engine capacity issue.
It’s important to consider the period in which this took place. The 1975 model year began about six months after the end of the OPEC embargo, which took place during the 1974 model year. During the embargo, big car sales suddenly tanked, and after it was over, there was a lot of uncertainty about how the market was going to react, which made production planning kind of a headache. Oldsmobile told the press that the 400-4V was going to be available as an alternative to the 455. Since the 455 was essentially a tall-deck 350 with a different bore and stroke, mostly built on the same lines, I read that to mean that Oldsmobile arranged to buy some 400 engines from Pontiac so that they could devote more of their own capacity to building 350s, which they expected to need in greater numbers. After that was already in motion, they did the math on anticipated production volume and said to Pontiac, “Hey, while we’re at it, can we get some 2V 400s as well?”
Interesting .
I don’t see why it’s such a bi deal, BOP engines were after all BOP engines .
This failed to sell rag top is interesting, I’d like to see more info or pictures on it to perhaps figure out why it didn’t sell .
-Nate