10 May 2016

This is the difference between Small and Big Blocks

Mouse and Rat, Turbo-Fire and Turbo-Jet, Small Block and Big Block. While the application of electronic engine controls and forced induction may challenge the old saying, there is still truth to the cliché ‘there is no replacement for displacement’. The 1960s saw manufacturers building engines for their product lines that generally topped out near 450 to 460 cubic inches, but not necessarily divided into different engine families.

As far as differentiating engine series, Chevrolet could be viewed as the most successful OEM. What is now known as the Chevy small-block ranged from the first 265-ci in 1955, all the way to 400-ci by 1970. But it is largely recognized for its ubiquitous 350-ci variant, which seems to have been produced countlessly. Chevy production big-blocks range from 348-ci to 454-ci in passenger cars, but have also been offered in other displacements for different applications. However, the difference between the two lines is distinct; stand the two blocks next to each other and telling which offers more capacity is easy.

Chevrolet introduced their first post-war, mass produced V-8 with 265-ci in both the Bel-Air and Corvette producing 162hp and 195hp, respectively. While the Turbo-Fire small-block’s development would continue, every subsequent small-block shares commonalties; one of which is bore spacing, or distance between the center of one cylinder bore and the next, measuring 4.4 inches. When comparing a small-block against a big-block, this is one of the design parameters that will ultimately influence the block’s external size and the total volume it can contain. If you want more volume (without making the block taller), the bores’ radii must be larger and thus farther apart meaning the cylinder case must be longer.

The basic design that is the small Chevy underwent several generations, with the currently produced LS-series considered the fifth. The first, however, was in production from ‘55 through 2003.

The big-block Chevrolet was introduced in 1958 and was primarily designed for larger passenger cars and light trucks. It fulfilled the need for an engine that produced more torque as cars became heavier. Less than a decade later it underwent noticeable changes, but was initially launched as the Turbo-Thrust V-8 and featured 348-ci displacement. The big-block first offered 250 hp with a single four-barrel carburetor, and the optional Super Turbo-Thrust produced 280 hp using three two-barrel carbs. Additionally, the combustion chambers were in the block. The Super Turbo-Thrust, with its uniquely shaped rocker covers, eventually grew to 409-ci (although an aluminum 427-ci V-8 was an RPO option for racers in 1963, too) before being replaced by the more common Mark IV series engines.

The new Mark IV series, initially offered in mid-1965 was built around the same 4.84 inch bore spacing as the 348-ci. However, its combustion chamber was moved into the cylinder head, and the intake and exhaust valve layouts were modified. This engine was offered displacing 396-ci, 427-ci and 454-ci during the late ‘60s and early ‘70s, and went through several iterations incorporating improvements and new technology.

Pontiac’s engine program took a different route however as they do not have a small- and big- block, but one engine architecture. Introduced in 1955, like Chevy’s small-block, the “Strato-Streak” displaced 287-ci and made 180 hp with a two-barrel carburetor, and 200 hp with a four-barrel carburetor. Over time, this engine grew all the way up to 455ci by the late 1960s without any changes to its external dimensions. Thus, Pontiac only has a single V-8 block as it was more than capable of competing with Chevrolet’s entire lineup.

In the same period, Ford’s most common offerings were the long-lived Windsor series of small-blocks, the mid-range FE series and the big 385 series. Introduced for the 1962 model year, the Windsor started at 221-ci for the intermediate sized cars in Ford’s lineup and eventually grew to a 351-ci displacement over its 39-year life. Ford’s smallest V-8 through this era, the Windor’s displacement varied by modifying the design’s deck height.

The FE engines topped out at 428-ci after being introduced in 1958 as small as 332-ci. This range contains the iconic Cobra Jets and Ford’s SOHC motor. It underwent notable changes during its life but its design falls between the small ford Windsor and the later 385 series. However, the bare block appears larger than the Windsor due to its deep skirt design.

Starting in 1968 Ford began offering, what is considered by many, their big block: The 385 series engines offered in 370-ci, 429-ci and 460-ci variants. The 460-ci variant was used in trucks and other heavy-duty applications into the late ‘90s.

Chrysler offered two different main lines of engines during this time. The LA was an evolution of their earlier poly-spherical A-series engines, which were both built on a 4.460 inch bore space. It started out in 1964 displacing 273-ci and grew as large as 360-ci by 1971. This engine saw a relatively long life, and evolved into Chrysler’s Magnum line, which was built into the 2000.

The RB-series was Chrysler’s larger line introduced in 1959 as a change to their B-series engines. While the change in the A line was designed to improve and lighten (L(ight) A series), B-series changes were centered around increasing the engine’s stroke longer and hence made the engine taller. The RB series started with a 383-ci displacement and grew into the 440-ci.

You cannot talk about Chrysler small and big blocks without discussing the Hemi, however. While it shares some dimensions with the 426 Wedge motors offered in the RB line, it is its own animal, and you would not say that someone has a big-block Chrysler Hemi, it’s just the Hemi. Built on the same 4.800 inch bore spacing as the Wedge, its massive cylinder heads and tall 10.72 inch deck height make it hard to fit in many engine bays, but allowed it to earn its “elephant” nickname for more than one reason.

So, what matters more when calling an engine a small- or big-block, really depends on whether the engine in question had a dimensional juxtaposition. Cadillac offered a 500-ci engine that was nearly the same size, dimensionally, as a small-block Chevrolet, but that does not make it a small-block Cadillac. And while this only a brief overlook at many engines manufactured over many years, it’s important to remember that in most cases accuracy depends on what manufacturers called the engines, not conventional perception.

41 Reader Comments

  • 1
    Mr. Horsepower Louisiana May 11, 2016 at 17:21
    Yes! I am glad you mentioned Pontiac! The one engine design that got it right the very first time, and was a total success on the streets and the track, and yet GM killed it, even though it powered the original muscle car, the GTO, because it was not as profitable as the cheaper to produce Chevy small block. I hate GM for their 'corporate engine' program, I hate them for their lame attempt at bringing beck the legendary GTO moniker, and I hate them for killing the Pontiac brand.
  • 2
    bruce arlington, va May 11, 2016 at 18:06
    Are the motor mounts for the same series motor (Chevy small-blocks for example) in the same place on all of them so if one would bolt in your car, all the others in that series also would without any needed modification too?
  • 3
    Kevin AZ May 11, 2016 at 18:08
    The Chrysler RB series did not include the 383 or 400. Those were still B series engines .
  • 4
    Steve Houstoon May 11, 2016 at 18:18
    Your information on the Ford engines completely left out the small block 335 series engines that includes the 351Cleveland and the 400 and 351M.
  • 5
    J B Florida May 11, 2016 at 18:26
    don't know U left out amc around 1956 to 1966 AMC made their V8,10" deck height 327 Ci ,, In 1966 AMC built a different V8 290 ci 200hp & 4 barrel 225 hp also ,343 ci with 280 hp in 1968 AMC came out with the 390ci , 315 hp,, 1970 amx changed the 290 to a 304 and the 343 to a 360 stayed with the 390 all 1970 were dog-leg type heads and the deck height was increased. in 1971 the 390 was replaced with a 401 ci -330 hp ,, all of these blocks were almost the same wall thickness and cyl bore were different,, you could take a 1966 290 use the 290 pistons and a 401 crank ( slight grinding so the crank would clear) and make it into a 273 ci. almost every part would interchange except pistons,, oh, most of these engines came with Clevite 77 bearings and chrome molly rings, they also came with forged cranks,& rods. to get these on a chevy or ford you had to go out and buy and install them. in 1987 Chrysler bought amc just to get the jeep.
  • 6
    Rod Napa Ca May 11, 2016 at 18:27
    Great SHORT STORY. I will watch how many comments come along that will enter into some debate about who did what and why. But I will start it off by narrowing down to a small comment: At least CHEVY kept two basic configurations whereby many accessories and mounts will pretty much--- "bolt on" . Bell-housings, Flywheels, engine mounts.water pump hose locations and more.. WHEN FORD has a 5 or 6 bolt "small block" FE and Cleveland blocks have different requirements for this stuff, then we have the Lima Blocks that look like a Cleveland and all the STUFF between the lines here I will not get into. Make is a nightmare to do an engine swap in a FoMoCo-- LemmeSeee--- What firing order is this thing---- is it a 289 302 or 351? what YEAR is the dang thing? what distributor works? What firing order is it? Oh-- GEEZ, my bell housing wont bolt up--
  • 7
    Richard Eames Florida May 11, 2016 at 18:52
    A very thorough explanation of the V-8 American engine.
  • 8
    Michael Fredericks Florida May 11, 2016 at 19:04
    Nice article - concise and the writer is well informed. More like this.
  • 9
    SAL SCACCO WEST BABYLON NY May 11, 2016 at 19:29
  • 10
    Dave Harvard, MA May 11, 2016 at 19:44
    I always wanted to know and after reading your description, I STILL want to know.
  • 11
    Bob Ohio May 11, 2016 at 20:15
    The Chrysler "B" engine actually started in 1958 with the 350ci option. Not 1959.
  • 12
    Barry Boricchio Sonora Ca. May 11, 2016 at 20:25
    thanks for your right up. you have some of the best reference and you do your home work. I will always like the Buick it fit in my 54 Chevy very well great torque motor . thanks barry
  • 13
    john johnson chattanooga, tennessee May 11, 2016 at 21:31
    Thanks for this trip down engine memory lane. Some details I never knew - most were conversations held long ago in a friend's garage! I wish kids were involved more in these enginesto keepthem alive!
  • 14
    Michael Croce NY May 11, 2016 at 21:53
    Wow, excellent, informative article about a subject that confuses almost anyone that hasn't been around these engines since their inception, especially when it comes to certain Chevy small blocks offering more displacement than certain Chevy big blocks. Would like to see more like this
  • 15
    Bill Gowin Georgia May 12, 2016 at 14:11
    You failed to mention that the Cleveland engine was the basis for the Boss 302 and 351 which is the main stay for Ford in NASCAR. Of course most people think the Chevy is the only hot rod engine.
  • 16
    Charles Fatseas TN May 12, 2016 at 14:52
    After reading your blog about the various paths of development that manufacturers in creating their engines, you failed to acknowledge the unique Buick 'nailhead' design that was unequaled at it's time for the linear torque that it created.
  • 17
    Jack Taggart Bath NY May 12, 2016 at 17:21
    you forgot to mention the biggest and fastest in 70 production engine put in a Buick 455, Stage 1 or stage 2 which either would walk all over those mentioned about 100 percent stock
  • 18
    James Martello Portland OR May 12, 2016 at 09:43
    Good article except for the fact that the Chevy 348 and respectively the 409 were neither small blocks or big blocks,, Like the Chrysler Hemi the 348-409 were in a class all their own,, The "W" block,,,
  • 19
    sean Ct May 12, 2016 at 10:29
    Interesting about the cadillac 500CI. Dies it weigh the same as a chev small block. Seems like it might make an ultimate v8, relatively compact with the cubes to put out some serious power. Yet we see so few high performance cars.
  • 20
    David FL May 12, 2016 at 10:49
    When I lived in NJ I had a 396 bored out to 402. In a Chevy Chevelle SS 396. I made the horsepower at 650. It did the 1/4 mile in 11.2 seconds at Raceaway Park in Englishtown.
  • 21
    Mark Nedrow Washington May 12, 2016 at 10:57
    The 361 cu in (5.9 L) B engine also introduced in 1958 was essentially the same as the 350 except with a larger 4 1⁄8-inch (100 mm) bore. In 1964, the Dodge Polara 500 came standard with a 315 bhp (235 kW) version of the 361 that had a four-barrel carburetor, dual-point distributor, and dual exhausts. Plymouth called their versions of the early B engine the Commando, variants of which included the Golden Commando and SonoRamic Commando. It produced 305 bhp (227 kW). DeSoto's B engine was named TurboFlash and produced 295 bhp (220 kW). The Dodge standard version was a 2-barrel with 295 bhp (220 kW) called the Super Red Ram with an optional variant that was called the D500 and produced 320 bhp (240 kW). The 361 would last until the end of the series, albeit for trucks only. In its early years, the 305-horsepower 361 was optional on many vehicles, and standard on, among others, the Dodge 880. The 361 had a fuel injected version in 1958 only.[1] Very few of fuel injected B engines were made, and only a handful—at most—remain since most were brought back to the dealer to be fitted with carburetors. My '65 Plymouth Satellite came with the 361.
  • 22
    dj ames Windsor On May 12, 2016 at 11:02
    Why is there no mention of the 305 SBC did it come out much later I have one in my 86 Vandura 1500 I find it a little under powered but it is a great engine **I have just turned 252378.9 kilometers on the van and it doesnt leak a drop of any fluid How lucky am I
  • 23
    Dan Archer Laveen Arizona May 12, 2016 at 12:32
    I have a '57 Chevy BelAir with a 350 ci engine 400 hp, it runs great. Thanks for the info ,keep it coming.
  • 24
    Herman SC May 13, 2016 at 14:08
    How can a discussion of the Chrysler LA engine not include the Viper V-10
  • 25
    Mike Stirling Ontario May 13, 2016 at 15:07
    Oldsmobile. How could you forget the Rocket engines?
  • 26
    Chris Winslow Traverse City, MI May 16, 2016 at 14:00
    @Bruce from Arlington, VA: Generally speaking yes, at least so far as the small block Chevrolet is concerned. What you're really asking is did the bell-housing or motor mount bosses on the block change year to year for a specific engine. Using the small block Chevrolet as an example, but not the rule, the bosses for the motor mounts did not change from the first side mount in 1958 through the end of production in 2003. Assuming you handled any issues with flex-plates or flywheels you could unbolt one and install another - any changes to the motor mounts happened either with the style of mount, or on the car's chassis. Now that is not to say that you can remove a small block Chevrolet and install a big block, that would be a whole different ball of wax. @Sean from Connecticut: Assuming stock iron components, the Cadillac 500 usually ends up around 600 lbs, '60s and '70s small blocks end up around 575 lbs and a big block Chevy around 680; so weight-wise it's in the middle. I have seen several in off road jeeps and some even adapted for use as towing motors, their stock valve train does not like use over about 5000 rpm and the relatively small production volume compared to the Chevrolet means that the aftermarket has not embraced them, which keeps parts cost high unfortunately - a major reason you see so few.
  • 27
    steve Ca May 16, 2016 at 11:17
    It's impossible to cover All information in one small article, but you did a great job of covering the key aspects for us shade tree mechanics.
  • 28
    Jim K California May 16, 2016 at 00:01
    I love the usual rounds of nitpicking in the comments. Nice article overall.
  • 29
    Richard A. Winslow Broad Brook ,CT. May 18, 2016 at 22:04
    Studebaker designed the 232" v-8 in it's 1951 Commanders. It made 120 hp. And was changed to 224" in 1955. In 1956 it was stretched to 259cu.in.,then later to 289 cu.in. The '57 Golden Hawk was supercharged to 275hp. In 1963 the supercharged R2 and R3 engines were available in all models. A 1963 Lark driven by 70 plus yr old Ted Harbit is presently all but unbeatable on the strip. Stude V-8s are powerful and sturdy.
  • 30
    Frank ILL Haliburton Canada June 9, 2016 at 11:26
    I still have my 1970 SS 454Chevelle That I bought brand new.
  • 31
    Greg Caffee NV June 12, 2016 at 18:34
    The Caddy 500 with a aluminum manifold weighs right about the same as a SBC. With a cam and headers is capable of around 500 HP. There are a couple of outfits in the U.S. that cater to nothing but big block Caddys. Head swaps can also increase the compression ratio without having to change pistons.
  • 32
    Loco Mikado Vancouver, WA September 24, 2016 at 19:36
    David, a 396 is a 402. The 396 is a displacement made up by marketing people, they figured it sounded better than 402.
  • 33
    Bob Crow Port St. Lucie, FL December 28, 2016 at 17:18
    Turbo Buick sayings: 1. Displacement is no replacement - for boost! 2. Life is too short to stay stock. 3. Due to poor economic conditions, I'm forced to drive a V6 now... 4. It's just a Buick, how fast can it be?
  • 34
    Gerald Thousand Oaks, CA December 28, 2016 at 17:20
    So, exactly what is the difference between a small block and a big block? You touched on bore spacing, but never finalized those comments as being the sine qua non for determining the difference between the two blocks.
  • 35
    Hoperator Corpus Christi,TX. December 28, 2016 at 19:56
    I would find it interesting to read about the engines produced for military use during WW2. I'm thinking Oldsmobile built radial engines for B-24 bombers. Those more knowledgeable than me could add some interesting information on military engines used in aircraft, boats, trucks etc...
  • 36
    Iain BC Canada December 28, 2016 at 23:22
    Actually, the original 396 was 395.97cid which is close enough to 396 for government work😁. When they took the bore out another .030 inches the displacement was 402, but as mentioned above gym had quite a bit invested in the 396 brand. I have a Cad 500 and has "square" bore and stroke and is within 75lbs of a small chevy massive torque though!
  • 37
    John Ft Wayne December 29, 2016 at 17:45
    Loco Mikado, the '68-'69 396 ci BBC had a 4.094" bore while the '70+ "396" BBC had a 4.125" bore (both had 3.76" stroke) giving it a 402 ci displacement. Chevy marketing kept the "396" name for its notoriety even though the actual displacement DID increase between '69 and '70 after GM lifted the 400 ci limit in mid-sized cars (i.e.: Chevelles). Mike, agree that Olds has been overlooked here. Considering their OHV V8 predates about everyone else's (1949), this is a glaring omission. The latest family of SBOs include the 307, 330, 350 and 403 (aka: "6.6 Litre" in late 2nd gen Trans Ams) and the taller deck BBOs include the 400, 425 and 455. The unique thing about Olds' SBs and BBs is that due to identical bore spacing, heads could be interchanged, as could timing chains, valve covers, water pumps, etc. Next to Pontiac's V8, I think Olds were the next most difficult to tell what was under the hood if you weren't keen on the paint color schemes used throughout the years.
  • 38
    Frank Branstrom Lionia Mi December 29, 2016 at 07:57
    Has anyone been to the Y Block Nationals in Columbus Ohio to see the Ford y Blocks run ? Eye opening performance with very little after market stuff , compared to other motors .
  • 39
    Ken Randall Calgary, Alberta December 29, 2016 at 11:41
    Insightful article all the way around. Obviously not all big blocks are created equally. I just fully restored my 68 Chevelle SS with its 'born with' b.b 396 350 h.p engine to factory spec's by 'having' to sleeve all 8 cylinder bores. A very costly venture to say the least. In hindsight I would have visited my local Chevy parts department and selected anyone of their LS engines.The dyno test results were dismal at best in comparison to GM's touted figures. Under 300 horsepower and nowhere near their advertised torque values. Bottom line ... under powered and over-rated with a sweet exhaust note under idle. Too bad the big three didn't have more stringent (true) test procedures back in the day, perhaps we'd all have slightly wider smiles on our face's some 40+ years after the fact!!
  • 40
    Don Chapman San Jose, CA December 29, 2016 at 00:00
    The Chevy small block was so popular because it had a small foot print and could fit in areas that other engine could'nt
  • 41
    roger vidamour windsor, ontario January 4, 2017 at 21:55
    i am still confused. what is the difference between a 427 cu. in. SBC and a 427 big block? Same cubic in. displacement! e.g. 400 sbc is larger in displacement than a 396 (?)

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