Mopar RB-Series Raised-Deck Big Block V8 Family Specs and Identification

Intro

The Mopar RB-series is Chrysler’s tall-deck big-block wedge family: 413, 426 wedge, and 440 cubic inches of the sort of torque that made two tons of Detroit stop feeling quite so ambitious. The 440 gets most of the applause now, the 426 spends eternity explaining that it is not a Hemi, and the 413 gets treated like somebody’s elderly uncle until a real long-ram or Max Wedge setup appears. That pecking order is convenient. It is also a lousy way to understand the family.

RB means raised block, and Chrysler raised it for a reason. The low-deck B-series was already a good big-block wedge, but its 3.375-inch stroke was not enough for the larger displacement Chrysler wanted. The taller RB block made room for a 3.750-inch stroke, and Chrysler liked that crank throw so well it kept it through all three major RB displacements. The 413, 426 wedge, and 440 are basically three progressively larger bores wrapped around the same long-stroke idea.

The 413 started the serious RB story in 1959. In big Chryslers and Imperials it supplied exactly what those cars needed: smooth torque, long-legged highway power, and enough reserve that the driver did not have to plan passing maneuvers by calendar. Chrysler then added ram induction, letter-car hardware, and eventually Max Wedge machinery and demonstrated that an engine perfectly capable of carrying rich people quietly could also become fairly antisocial when given the right parts.

The 426 wedge sharpened that performance side. In Max Wedge form it became one of Chrysler’s nastiest factory drag-racing engines before the Hemi arrived and sucked most of the oxygen out of the history books. That does not make every 426 wedge a Max Wedge, and it certainly does not make one a 426 Hemi. Same cubic inches, different heads, different architecture, different history, and usually a very different amount of money being requested by the fellow trying not to say “wedge” too loudly.

Then came the 440 in 1966, and Chrysler finally had the big wedge that could do nearly everything without needing an explanation. Luxury cars, muscle cars, police cars, towing duty, marine service, motorhomes, ordinary big sedans, Magnums, Super Commandos, TNTs, Six Packs, Six Barrels — the 440 got spread across the corporation like black pepper. That breadth is exactly why “it’s a 440” tells you remarkably little about the engine beyond its displacement.

The 440 also became the practical performance hero because it made huge torque without Hemi complexity or Hemi money. A good 440 in a heavy street Mopar is one of those combinations that makes complicated engineering arguments seem unnecessary. Press the throttle, feel the car leave, and save the airflow dissertation for somebody with smaller cubic inches.

There are catches, naturally. RB and low-deck B engines are related, but the taller deck changes intake width and other fitment assumptions. Early and late 440 rotating assemblies do not all use the same balance arrangement. Work-duty engines can carry completely different cooling, accessory, pan, flywheel, and manifold hardware. Performance badges, multiple carburetors, orange paint, and HP stories all need proof because nearly every desirable RB part has spent fifty years learning how to move from one engine to another.

So the RB family deserves to be judged by what each engine actually was. The 413 established the tall-deck torque formula. The 426 wedge showed how vicious that formula could become in factory competition trim. The 440 turned it into one of Detroit’s great all-purpose big-block engines. Three bores, one 3.750-inch stroke, plenty of common architecture, and absolutely no excuse for ordering parts because somebody said “big-block Mopar” with confidence.

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Overview

Chrysler created the RB because the original low-deck B-series had one obvious limitation: there was only so much stroke it could swallow before somebody had to move the roof. The B engines used roughly a 9.98-inch deck and a 3.375-inch stroke. Chrysler wanted more displacement and more crank leverage, so it raised the deck to roughly 10.72 inches, stretched the connecting-rod and rotating package around a 3.750-inch stroke, and created the aptly named Raised Block. No poetry required. The block was taller because Chrysler raised the block.

That taller deck is the feature every RB discussion needs nailed down first because B and RB engines otherwise look related enough to cause trouble. Both are Chrysler big-block wedges with 4.800-inch bore spacing, front-mounted distributors, in-block camshafts, pushrods, and shaft-mounted rockers. The extra RB deck height spreads the heads farther apart, which makes the intake manifold wider and changes enough surrounding geometry that “Mopar big block” is useful only until somebody reaches for a parts catalog.

There was even an early raised-deck 383 RB in certain 1959–1960 Chrysler applications, because Chrysler apparently believed one 383 architecture would have made future identification too easy. It is not part of the 413/426/440 lineup covered here, but it proves the point: displacement numbers do not identify block families. Measure and read the iron before letting familiar numbers make decisions.

The 413 became the first major large-displacement RB, using a 4.1875-inch bore with the family’s 3.750-inch stroke. That combination gave Chrysler exactly the engine it needed as the first-generation Hemi disappeared from normal passenger-car use. The wedge was simpler and cheaper to build, easier to package, and entirely capable of producing the torque expected in New Yorkers, Imperials, Chrysler 300s, and other machinery that regarded curb weight as somebody else’s concern.

In those regular passenger applications, the 413’s job was refined force. Big cars with tall gearing need torque more than theatrics, and the extra stroke gave Chrysler plenty. That same basic engine could loaf down the highway quietly enough for an Imperial owner and still have enough reserve that opening all four barrels did not require advance notice from the transmission.

Chrysler’s ram-induction experiments gave the 413 a much more interesting second personality. The long-runner systems used intake tuning to strengthen cylinder filling where heavy street cars could actually use it. They look like the carburetors were trying to escape to opposite fenders, but the plumbing had a purpose. Chrysler understood pressure-wave tuning long before anybody could buy a polished aluminum intake with “TORQUE” cast into it in letters large enough to frighten physics.

The 413 then crossed from expensive-car performance into genuine factory drag-racing territory. The 1962 Maximum Performance Wedge package brought high compression, serious heads, aggressive cam timing, cross-ram dual four-barrel induction, special exhaust, and the sort of calibration expected when quarter-mile times ranked above idle quality. This was not a New Yorker engine with the air cleaner turned around. Chrysler built a competition package.

That Max Wedge history is where ordinary 413s begin receiving promotions they never earned. Passenger-car engines, long-ram letter-car combinations, truck engines, industrial 413s, and genuine Maximum Performance engines share displacement but not purpose or value. Heads, compression, intake, carburetors, camshaft, exhaust, block details, dates, stampings, and vehicle history all need to agree before an ordinary old RB starts charging Super Stock tuition.

For 1963 Chrysler increased bore to 4.250 inches while leaving the 3.750-inch stroke alone, producing the 426 wedge. That is the RB development pattern in its purest form: same crank throw, larger cylinders. More bore gave more cubic inches and more breathing room without abandoning the basic tall-deck wedge package.

In Max Wedge form the 426 carried Chrysler’s factory drag program forward with Stage II and Stage III hardware, specialized heads, high compression, aggressive cams, cross-ram induction, special exhaust, and competition intent. Dodge Ramcharger and Plymouth Super Stock combinations made the 426 wedge one of the defining engines of the pre-Hemi Super Stock wars. The Hemi later stole the headlines. It did not travel backward through time and win those races for the wedge.

The 426 also existed in milder Street Wedge form, which is important because a 426 block does not become Max Wedge iron merely from living through the same model years. Some block castings overlapped between ordinary and Maximum Performance use. Genuine Max Wedge identification can require pad stampings, casting dates, special cylinder-bore reliefs, correct heads, induction, exhaust, and application evidence. Rare-engine prices have a remarkable ability to turn ordinary cast iron into detective work.

Then there is the other 426 problem. Chrysler’s Gen II Hemi also displaces 426 cubic inches and even uses the same nominal 4.250-inch bore and 3.750-inch stroke. That is where the similarities stop being useful. The RB 426 wedge uses conventional wedge heads and RB valvetrain, intake, piston, and exhaust architecture. The Hemi uses enormous hemispherical heads, central plug tubes, its own valvetrain and block details, and enough extra reputation to make strategic vagueness profitable.

If somebody is selling a “426” and keeps carefully avoiding the words Hemi or wedge, make him pick one before discussing money. Cubic inches are not a combustion-chamber design.

The 440 arrived for 1966 by repeating Chrysler’s favorite RB trick one last time. Stroke stayed at 3.750 inches. Bore grew again, this time to 4.320 inches. That brought displacement to 440 cubic inches without changing the basic crank throw that had served the 413 and 426. Chrysler had found a useful stroke in 1959 and saw no reason to redesign it simply to give future bench racers more dimensions to memorize.

Those three factory dimensions tell the family story neatly: 4.1875 × 3.750 for the 413, 4.250 × 3.750 for the 426 wedge, and 4.320 × 3.750 for the 440. Same deck family. Same nominal stroke. Bigger bore each time. The engines can behave very differently because compression, heads, camshaft, induction, exhaust, gearing, and vehicle application change dramatically, but the mechanical family progression itself could hardly be cleaner.

The 440 succeeded because Chrysler gave it more jobs than the earlier engines ever had. It could pull a New Yorker or Imperial around without breathing hard, serve police and fleet duty, tow, work in marine and motorhome applications, or become a Magnum, Super Commando, TNT, Six Pack, or Six Barrel engine when performance took priority. That kind of production breadth is why 440 parts and cores remained familiar long after the 413 and 426 wedge became specialty conversations.

The single-four-barrel performance 440s deserve respect before the multiple-carb versions arrive. A properly equipped Magnum, Super Commando, or TNT combined compression, cam timing, good induction, useful heads, and decent exhaust around enough displacement to produce the kind of midrange torque that makes a heavy Mopar feel considerably lighter than the registration says.

The Six Pack and Six Barrel combinations simply turned the argument up another notch. Three two-barrel carburetors, stronger supporting hardware, and the right factory package gave the 440 one of the best-known wedge reputations of the muscle era. It also created another identification trap. There is no magical Six Pack bare block that announces itself from twenty feet away. An intake can move. Carburetors can move. Air cleaners can move. Valuable history should require something heavier than bolts to establish it.

The 440’s long production run also carried it straight through Detroit’s transition from high compression and horsepower advertising into emissions controls, lower compression, cast crankshafts, work-duty applications, and horsepower numbers nobody was putting on bedroom posters. That does not make every later 440 worthless. It means a 1970 HP engine and a late motorhome core should not be judged as though Chrysler built them for the same assignment.

Rotating-assembly balance is one place where that production evolution can bite a builder. Early 413s, 426 wedges, and early 440s commonly used forged-crank internally balanced arrangements. Later cast-crank 440 combinations moved to external balancing and require the correct damper and rear balance hardware. Six Pack and other heavy-rod forged-crank packages add their own wrinkle. If the crank, damper, converter, flexplate, or flywheel come from different family reunions, the engine will announce the disagreement at operating rpm.

RB cylinder heads interchange broadly enough to be useful and broadly enough to cause lies. A desirable head casting proves what heads are bolted on the engine today. It does not establish the block displacement, original package, or vehicle. The same goes for intakes, exhaust manifolds, distributors, carburetors, and dress hardware. Chrysler used bolts on all of them, which unfortunately means restorers and storytellers have had equal access.

Work-duty engines bring another set of cautions. Truck, motorhome, industrial, and marine RBs can carry different heads, cooling systems, oil pans, flywheels, governors, accessory drives, manifolds, mounts, and years of hard service. Some are excellent cores because nobody ever tried to race them. Some spent decades pulling several tons uphill while running hot and receiving maintenance whenever the owner remembered. “Motorhome engine” is a description of employment, not a metallurgical certification.

Choosing within the family therefore depends on the car more than the scoreboard. A correct 413 belongs in an early Chrysler, Imperial, letter car, or historically significant application where the engine itself is part of the vehicle’s identity. A documented 426 Max Wedge or Street Wedge deserves preservation because replacing rare period hardware with generic speed parts solves the wrong problem. A 440 is usually the easiest general-purpose choice when the project starts with an empty engine bay and simply wants big RB torque.

That does not mean every 413 should be discarded for a 440 or every 426 should spend its life wishing it were a Hemi. More displacement is useful. Correctness is useful too. A proper 413 in a car built around it can be more valuable and more interesting than a generic 440 swap. A real 426 Max Wedge has historical importance a larger modern combination cannot purchase by making more dyno power.

The RB family’s great strength is that Chrysler got the basic architecture right and kept developing it without unnecessary reinvention. Raise the deck. Use the 3.750-inch stroke. Start at 413. Add bore for 426. Add more bore for 440. Then change the surrounding hardware according to whether the customer wanted a luxury car, drag racer, police car, muscle car, boat, motorhome, or something else capable of making gasoline disappear quickly.

That same simplicity is why sloppy identification is so unnecessary. Three major displacements share the same stroke, related blocks, interchangeable-looking pieces, and sixty years of parts swapping. Read the pad. Read the casting. Check the dates. Know whether the block is B or RB. Verify the rotating assembly and balance hardware. And when somebody says “426,” make him finish the sentence. Chrysler already made the engines complicated enough. There is no need to let the sales pitch help.

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General Family Specs

Engine Family	Mopar RB-Series Raised-Deck Big Block Wedge V8	Major Factory Engines in This Family	413, 426 wedge, 440
Production / Use Era	Late 1950s through late 1970s in major factory passenger-car, performance, police, truck, marine, industrial, and service use, depending on engine and application	Configuration	90-degree V8
Valve Layout	OHV / pushrod, 2 valves per cylinder	Cam Location	In-block camshaft
Block Style	Raised-deck Chrysler big-block wedge	Deck Height	Taller RB deck height, above the low-deck B-series family
Bore Spacing	4.800 in	Cylinder Head Layout	Wedge combustion chamber heads
Rocker Layout	Shaft-mounted rocker arms	Distributor Location	Front-mounted, angled into block
Common Block Material	Cast iron	Common Head Material	Cast iron
Oiling System	Wet sump	Typical Induction	2-barrel, 4-barrel, multi-carb performance, and application-specific carbureted setups depending on year and engine
Typical Bellhousing Pattern	Chrysler big-block pattern; verify crank, converter, flywheel/flexplate, balance, and transmission-year details	Major Identification Caution	RB raised-deck engines aren’t low-deck B engines, and the 426 wedge isn’t the 426 Hemi

Those are the broad family facts. They put the RB in its own tall-deck lane, which is where it belongs. The family shares Mopar big-block wedge DNA with the B-series, but shared DNA doesn’t make the parts pile universal.

Deck height is the big separator. RB intakes are wider than B intakes, rotating assemblies differ by displacement, and application hardware can change more than a seller wants to admit. A part can be Mopar big-block hardware and still be wrong for the engine on the stand.

Balance details also need attention, especially when dealing with later 440 combinations, replacement parts, torque converters, flywheels, and mixed rebuilds. Chrysler gave builders enough combinations to make guessing expensive. Don’t help the problem.

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Identification

A Mopar RB is the raised-deck Chrysler big-block wedge. The distributor sits at the front, the engine carries Chrysler’s big-block wedge heads and shaft-mounted rocker gear, and the block is physically taller than the closely related B-series 350/361/383/400 family.

That last part is the important one. A 383 B and a 440 RB can look remarkably similar after fifty years of swapped valve covers, intakes, accessories, paint, and air cleaners. The RB block has roughly a 10.72-inch deck height, compared with roughly 9.98 inches for the low-deck B. That extra height spreads the heads farther apart and requires the wider RB intake manifold.

Fortunately, Chrysler gave us a much better assembled-engine clue than standing beside the fender with a ruler.

The Front Identification Pad Separates B From RB

Look at the top front of the block around the distributor and intake valley.

On an RB engine, the machined identification pad is a raised, nearly horizontal surface at the front of the block just ahead of the intake valley. On a low-deck B engine, the pad sits lower alongside the distributor and follows the angle of the block deck.

Once you know those two locations, separating a 413/426 wedge/440 RB from a 361/383/400 B engine gets considerably easier.

The RB pad is also where Chrysler stamped some of the most useful information on the entire engine, so clean it before deciding what you bought.

There Was Also an Early 383 RB

Before anybody turns “RB means 413, 426, or 440” into a universal law, Chrysler built an early raised-deck 383 RB for certain 1959–1960 applications.

That engine is not the familiar low-deck 383 B that later became a muscle-car staple. Same displacement number. Different deck height and intake width.

It is outside the three-engine lineup covered on this page, but it matters when identifying an unknown early Chrysler big block. Chrysler reused numbers long before the internet made doing that inconvenient.

Read the Stamped Identification Pad First

On an original production engine, the horizontal front pad can identify model year, displacement, assembly information, and sometimes performance or machining details.

Chrysler’s exact stamping format changed over the years, so decode the pad according to the engine’s production period rather than expecting every RB from 1959 through 1979 to use one format.

By the muscle-car era, the first character commonly identified model year, followed by displacement. Examples include:

• B 440 — 1966-model 440.
• C 440 — 1967-model 440.
• D 440 — 1968-model 440.
• E 440 — 1969-model 440.
• F 440 — 1970-model 440.
• G 440 — 1971-model 440.

Earlier 413 and 426 wedge engines use their own period-appropriate series markings. A genuine 1964 426 Street Wedge, for example, can carry a V 42-style stamping, while Max Wedge pad markings follow a different performance format.

The important point is not memorizing every stamp ever struck at Trenton. It is recognizing that the pad tells you considerably more than orange paint ever will.

HP and HP2 Markings

Muscle-era 440 engines may carry HP on the identification pad when Chrysler assembled them as high-performance engines.

That is meaningful evidence of the original engine assembly. It does not mean Chrysler cast a magically stronger “HP block.” Ordinary and high-performance 440s commonly started with the same basic block casting.

You may also encounter HP2. The extra 2 is associated with production-shift identification, not some secret second level of horsepower. An HP2 block is not automatically stronger, rarer, or better than an otherwise equivalent HP block.

The performance package came from the crank, rods, pistons, camshaft, induction, exhaust, and other assembly details. The letters on the pad identify how Chrysler built it. They do not add iron between the cylinders.

Find the Block Casting Number

The raised block casting number is normally found along the side of the block below the cylinder head. The casting date is usually nearby or elsewhere along the block side depending on casting generation.

Useful RB casting numbers include:

• 1852029 — appears in early 413 and certain early performance/426 applications.
• 2120529 — common 413 casting.
• 2205697 — appears in 413 passenger production and also some 426 wedge applications.
• 2468030 — another casting associated with both 413 and 426 wedge use.
• 2406730 — important 1963–1964-era 426 wedge / Max Wedge casting.
• 2532230 — later 426 wedge casting, particularly associated with 1965-era Street Wedge production.
• 2658836 — heavy-duty truck/industrial casting commonly encountered as a 413 and also found in other RB work-duty applications.
• 2536430 — familiar 1966–1972 440 casting.
• 3698830-440 — later 440 casting family.
• 4006630-440 — late-production 440 casting used through the end of RB production.

That list explains why casting-number identification needs a little maturity. Several early RB castings appear under more than one displacement. A 2205697 does not automatically settle 413 versus 426. Neither does 2468030.

The casting identifies the iron. The stamped pad, date, application, and bore tell you how Chrysler finished it.

Later 440 Blocks Often Make Life Easier

A later 440 casting commonly includes 440 as part of the raised casting identification, such as 3698830-440 or 4006630-440.

That makes a late 440 block fairly difficult to mistake for a 413 unless somebody is trying exceptionally hard.

It still tells you the block, not necessarily the displacement of a modified engine. A 440 block with a stroker crank can be 500-plus cubic inches while the side of the block continues insisting it is 440. Cast iron does not receive software updates.

Check the Casting Date

The casting date tells you when the bare block was poured. It should precede the engine-assembly date and, on an original engine, the vehicle build date.

That is especially valuable with desirable 426 wedge, Max Wedge, 440 Magnum, Six Pack/Six Barrel, and restoration claims.

A casting produced after the car was assembled did not come down the line in that car. When the dates disagree, believe the calendar before the sales pitch.

Partial VIN and Engine Serial Numbers

Later RB blocks add another powerful piece of evidence.

During the 1968 production transition, applicable engines may carry vehicle-identification stamping around the rear block/bellhousing area. Beginning with 1969 production, the familiar partial-VIN pad is low on the passenger side of the block just above the oil-pan rail.

When the partial VIN matches the vehicle and the block casting date and assembly information also make sense, that is strong evidence that the block belongs to that car.

A warranty or service-replacement block may legitimately lack the original vehicle VIN. Missing numbers therefore require context. Fresh-looking numbers on a freshly machined pad require considerably more suspicion.

413

The factory 413 uses a 4.1875-inch bore and 3.750-inch stroke.

It was the original large-displacement RB and appeared in Chrysler passenger cars, Imperials, performance applications, trucks, motorhomes, marine equipment, and industrial service over a surprisingly long life.

That broad use means a 413 can wear very different hardware depending on where it spent its working years. A passenger-car 413 and a heavy-duty industrial 413 can look like distant relatives once water pumps, heads, manifolds, governors, pans, flywheels, and accessories are compared.

The common 2120529 and 2205697 casting families are useful passenger-engine clues. The 2658836 heavy-duty block points strongly toward truck or industrial ancestry.

The Heavy-Duty 2658836 Block

The 2658836 industrial RB block deserves special mention because it has created plenty of strange engines over the years.

It was commonly finished as a heavy-duty 413 and often came with the enormous five-bolt truck water-pump housing, large truck cylinder heads, and other unmistakable work-duty hardware.

Internally, the casting has enough cylinder material that many have been bored substantially larger. Chrysler itself also used the casting in more than one heavy-duty RB application.

So a 2658836 casting is excellent evidence that you found heavy-duty RB iron. It is not a reliable promise that the cylinder bores are still factory 413 size.

If somebody already bored it to 4.320 inches, calling it a 413 because that is how the casting commonly started life is mostly nostalgia with a dial bore gauge sitting nearby.

426 Wedge

The factory 426 wedge keeps the same 3.750-inch RB stroke and increases bore to 4.250 inches.

The cylinder heads remain conventional Chrysler wedge heads. That one fact separates the 426 wedge from the Gen II 426 Hemi before a casting number is ever read.

The 426 wedge existed in both serious competition form and more conventional Street Wedge form. Those are not interchangeable value claims.

426 Wedge Versus 426 Hemi

The number 426 proves cubic inches. It does not prove Hemi.

The RB 426 wedge uses wedge heads, normal big-block wedge valve covers, and wedge intake/exhaust architecture. The Gen II Hemi uses enormous hemispherical heads, central spark-plug tubes, dual rocker-shaft architecture, and the unmistakable wide Hemi top end.

The factory Hemi block also carries the familiar 2468330 casting family rather than the ordinary wedge castings discussed here.

If a seller keeps saying “426” while carefully avoiding the word “wedge,” make him finish the sentence before the price finishes you.

Max Wedge: Casting Number Alone Does Not Prove It

The Max Wedge is where RB wedge identification starts costing real money.

The 1962 maximum-performance engine used 413 cubic inches. For 1963–1964 Chrysler moved the package to 426 cubic inches. These engines used special heads, cross-ram induction, exhaust, camshaft, compression, and other competition hardware.

For 1963–1964, the 2406730 block casting is strongly associated with the 426 Max Wedge.

Unfortunately for anybody looking for one magic number, Chrysler also used the 2406730 casting for 426 Street Wedge production.

A real Max Wedge block therefore needs more evidence than “730 casting.”

Max Wedge Cylinder-Bore Notches

One useful block-level clue is found at the top of the cylinders.

Original 426 Max Wedge blocks were machined with relief notches at the tops of the cylinder bores to provide clearance for the large exhaust valves used with Max Wedge heads.

The contemporary Street Wedge did not need those same large-valve reliefs.

That means a 2406730 casting with the correct factory-style bore notches is much more interesting than an otherwise identical casting with ordinary cylinder tops.

It still deserves correct pad stamping, date, heads, induction, and application evidence before Max Wedge money changes hands.

Max Wedge Pad Stamping

Original Max Wedge engines also use distinctive identification-pad markings rather than the ordinary Street Wedge format.

The performance stamp can include MP for Maximum Performance along with displacement and, on high-compression versions, HC. Period stamping font and character size also differ from ordinary passenger-engine markings.

A 1964 Street Wedge may show a V42-style pad while a genuine Max Wedge from the same era carries the special maximum-performance identification.

When an engine is worth enough that somebody might restamp it, font, pad machining, casting date, and assembly chronology all matter. Rare-engine identification eventually becomes detective work because rare-engine prices eventually attract detectives from the other side too.

440

The 440 keeps the RB-family 3.750-inch stroke and opens the bore to 4.320 inches.

It arrived for 1966 and became the best-known RB wedge because Chrysler used it everywhere: luxury cars, police packages, muscle cars, trucks, motorhomes, marine applications, and enough swaps to make originality a separate investigation.

The common early casting is 2536430. Later blocks moved through the 3698830-440 and 4006630-440 families.

Casting number and front pad usually settle whether an original block is a 440. They do not settle whether it is a Magnum, Super Commando, Six Pack, Six Barrel, police, marine, motorhome, or ordinary passenger engine.

440 HP Claims

A muscle-era high-performance 440 normally carries an HP marking on the front identification pad along with year/displacement and assembly-date information.

That is useful because an ordinary 440 block and an HP 440 block are not fundamentally different bare castings. The performance identity came from the assembled combination.

Correct heads, camshaft, intake, carburetor, exhaust manifolds, distributor, windage equipment, rotating assembly, and vehicle application should support the HP claim.

A 2536430 block without the rest of the evidence is a 440 block. Do not promote it merely because there is room on the classified ad.

440 Six Pack / Six Barrel Claims

The 440 Six Pack and Plymouth Six Barrel engines deserve even more checking because the induction package and name add substantial collector value.

There is no unique Six Pack bare-block casting. The block is fundamentally a 440 block.

The original engine should have the correct production period, HP pad marking, internal rotating hardware, induction, heads, exhaust, and—most importantly when originality is claimed—a partial VIN that matches a vehicle originally coded for the Six Pack/Six Barrel package.

A triple-carburetor intake is valuable. It is also held on with bolts.

If the engine is claimed as original to a Six Pack car, make the VIN and vehicle documentation do the heavy lifting.

Balance Hardware Is a Useful 440 Era Clue

Early 413 and 426 wedge engines use forged crankshafts and normal internally balanced RB rotating assemblies.

Early 440 production also used forged cranks. Chrysler later introduced cast-crank 440 combinations that require external balance.

The harmonic damper makes a useful assembled-engine clue. A normal forged-crank damper is essentially neutral, while a cast-crank 440 damper carries a substantial offset balance weight. Many are clearly identifiable by shape, and some factory pieces are marked for cast-crank 440 use.

Later cast-crank engines also require the correct rear balance through the torque converter, flywheel, or appropriate flexplate arrangement.

Do not use that clue carelessly. Performance 440s used several different rotating combinations, and the famous Six Pack/Six Barrel forged-crank assembly used heavy rods that required its own balance correction. An offset-looking damper does not automatically mean “cheap cast crank.”

Balance hardware identifies the rotating package when the pieces are original. It does not identify the block casting.

Heads Identify the Heads

RB wedge cylinder heads interchange broadly with B-series big blocks, which makes them useful application evidence and lousy displacement gauges.

A Max Wedge head, 915, 906, 346, 452, or another desirable casting tells you what cylinder heads are bolted to the engine.

It does not tell you whether the block underneath is 413, 426, or 440.

Correct casting dates and several pieces of matching original hardware can strongly support a claimed factory package. One desirable pair of heads proves somebody found two desirable heads.

All Three RB Engines Share the Same Factory Stroke

Mechanically, the factory RB progression is beautifully simple. The 413, 426 wedge, and 440 all use the same nominal 3.750-inch stroke.

Chrysler increased displacement by increasing bore:

• 413: 4.1875-inch bore.
• 426 wedge: 4.250-inch bore.
• 440: 4.320-inch bore.

That means a stroke measurement alone does not separate these three stock engines. If the block stamp and casting information have disappeared or become suspicious, cylinder diameter is what finally tells the factory displacements apart.

Common Identification Mistakes

• “It is a big-block Mopar, so it is a 440.”
  Chrysler built B and RB big blocks in enough displacements to make that shortcut useless.
• “The intake fits, so it must be RB.”
  A stock RB intake is wider than a B intake, but aftermarket adapters and modified combinations exist. Check the identification pad and block.
• “It says 426, so it is a Hemi.”
  The 426 wedge is a real RB wedge engine. Look at the cylinder heads before your wallet gets involved.
• “2406730 means Max Wedge.”
  The casting also appeared under Street Wedge applications. Check bore notches, pad stamping, dates, and supporting hardware.
• “Every 413 block can only be a 413.”
  Some heavy-duty castings were used or modified across applications, and plenty have been bored much larger during rebuilds.
• “HP means a special stronger 440 block casting.”
  HP identifies the high-performance engine assembly. The basic block casting commonly served ordinary engines too.
• “HP2 is better than HP.”
  The extra 2 is a production-shift marking, not another performance level.
• “A Six Pack intake proves a factory Six Pack engine.”
  It proves the intake. A true original-engine claim needs pad, VIN, date, vehicle, and rotating-assembly evidence.
• “A weighted damper always means a cast-crank 440.”
  Six Pack and other special forged-crank combinations also used balance corrections. Identify the exact damper and rotating assembly.
• “All 440 blocks from the motorhome years are weak thin-wall junk.”
  Late blocks vary. Some 4006630-440 castings have very substantial main-saddle support, and the casting number alone does not tell you which internal webbing version you have.

What Evidence Deserves Trust?

• Front distributor, Mopar wedge heads, big-block proportions: strong Chrysler big-block wedge identification.
• Raised horizontal front identification pad: strong RB-family identification.
• Taller deck and wider intake: strong B-versus-RB evidence.
• Paint, decals, valve covers, air cleaner: decoration.
• Front pad displacement/year stamping: strong evidence of how Chrysler originally assembled the engine.
• Block casting number: strong evidence, but several early 413/426 castings overlap.
• Casting date: strong chronological evidence.
• Partial VIN where applicable: strong evidence tying a production block to a particular car.
• Max Wedge bore notches and correct MP/HC-style pad markings: strong evidence when casting date and hardware agree.
• HP marking: strong evidence for original high-performance engine assembly, not a unique bare block.
• Damper, converter/flywheel, and crank identification: useful evidence of the rotating assembly and balance configuration actually present.
• Heads, intake, carburetion, exhaust, distributor, and accessories: supporting application evidence because every one can be changed.
• Measured bore and stroke: final mechanical identification.

Most stock RB engines can be identified confidently without removing a cylinder head. Find the raised horizontal identification pad, read the displacement and production markings, find the block casting number and casting date, and check the partial VIN when the production year calls for one.

Those steps usually separate a 413, 426 wedge, and 440 and tell you whether the rest of the story is even possible.

The real detective work begins when somebody adds Max Wedge, HP, Magnum, Six Pack, Six Barrel, Police, numbers-matching, or some other word that makes the price climb. Those claims require the surrounding hardware and vehicle evidence to agree with the block.

When rebuilding, stroking, overboring, industrial conversions, or missing stampings have erased the easy answer, measure it. Bore and stroke are the ultimate identification test. All three factory engines share the same 3.750-inch stroke. The factory displacement difference is in the bore.

Bore / Stroke Reference

Displacement	Bore	Stroke
413	4.1875 in	3.750 in
426 Wedge	4.250 in	3.750 in
440	4.320 in	3.750 in

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Shared Design Patterns

The 413, 426 wedge, and 440 share one raised-deck RB foundation: 4.800-inch bore spacing, wedge-head architecture, shaft-mounted rockers, and the taller block Chrysler used to carry a 3.750-inch stroke. Mechanically, the family is remarkably straightforward. All three use that same 3.750-inch stroke. Chrysler increased displacement by opening the bore.

The 413 starts the progression with a 4.1875-inch bore and 3.750-inch stroke. Its roughly 10.725-inch deck height gives the longer RB rotating assembly room that the low-deck B-series architecture did not provide. This is the basic RB formula the later 426 and 440 continue: tall block, long stroke, wedge heads, and plenty of crank leverage.

The 426 wedge keeps the 3.750-inch stroke and enlarges the bore to 4.250 inches. That means the additional displacement comes from cylinder diameter rather than more crank throw. The 426 is therefore not a mechanically separate middle branch of the RB family. It is the same raised-deck recipe with more bore and more breathing room than the 413.

The 440 repeats the move one more time. Stroke remains 3.750 inches while bore grows to 4.320 inches. That gives the 440 its additional displacement without changing the basic stroke that defined the RB family from the beginning. More bore means more cubic inches and more room around the valves, while the long-stroke torque character of the raised-block architecture remains underneath it.

That gives the RB family a clean mechanical progression: 4.1875 × 3.750 for the 413, 4.250 × 3.750 for the 426 wedge, and 4.320 × 3.750 for the 440. Same stroke. Same raised-deck wedge foundation. Progressively larger bore.

So the 413, 426 wedge, and 440 are best understood as three bore sizes wrapped around the same basic RB idea. The 413 establishes the tall-deck, long-stroke package. The 426 adds bore. The 440 adds more bore again. Performance packages, induction, compression, heads, and applications can make individual versions behave very differently, but the basic family tree is simple: Chrysler kept the crank throw and kept opening the cylinders.

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Choosing Within This Family

The RB family gives three different reasons to stay with Chrysler’s raised-deck wedge. The 413 is the early torque and restoration engine. The 426 wedge is the period-performance choice, especially when genuine Max Wedge history is involved. The 440 is the broad-use street bruiser and usually the strongest general-purpose choice when originality does not dictate the answer.

Choose the 413 when early RB identity matters. A correct Chrysler, Imperial, 300, long-ram application, or other early big-Mopar installation gives the 413 a reason to stay exactly where it belongs. A complete standard 413 can also make a smooth, strong driver with plenty of old-Mopar torque. Its smaller bore and narrower parts path make it less attractive than a 440 when the only goal is maximum street performance from loose iron.

Preserve special 413 hardware rather than turning it into a generic performance build. Genuine long-ram, letter-car, Max Wedge, or Super Stock-related combinations carry value because of the complete package and history. Those engines deserve verification and careful rebuilding, not random modernization that throws away the parts that made them important.

Choose the 426 wedge when correctness or early-1960s performance identity is the assignment. A proper Street Wedge car, documented Max Wedge package, Super Stock connection, or period Mopar performance build gives the 426 a strong reason to exist. A well-built standard 426 wedge can also make a serious street engine without borrowing Hemi mythology.

The 426 wedge becomes harder to justify as a random performance core. If originality and period identity are not part of the job, the 440 generally offers an easier route to big RB street torque, while a low-deck 400 may be the better foundation when modern stroker packaging is the priority. Rare-engine money should buy more than a famous displacement number.

Choose the 440 when the goal is broad street usefulness and big torque. Its larger bore and 440 cubic inches give it the strongest displacement advantage in the RB family, and its broad production history and parts support make it the easiest member to build around for a cruiser, muscle car, heavy street car, tow-oriented application, or general performance project.

The 440 is usually the family choice when starting from scratch, but the exact version still matters. Early performance engines, Six Pack and Six Barrel packages, Magnum, Super Commando, TNT, police engines, later low-compression engines, and truck or motorhome cores do not start from the same place. A later low-compression 440 may need substantially more compression planning than its famous displacement suggests, while a genuine factory performance engine may deserve preservation rather than wholesale modification.

Do not automatically replace a correct smaller RB with a 440. A 440 may provide more displacement, easier parts sourcing, and stronger general street potential, but a correct 413 or 426 wedge can be more important to the vehicle it belongs in. More cubic inches can improve the performance answer while making the historical answer worse.

Across all three engines, condition and completeness matter more than reputation. A complete, sound 413 or 426 with its original supporting hardware can be a better project than a cracked, worn, incomplete 440 bought because the number looked better. None of these engines is improved by paying machine-shop money to rescue the wrong core.

The short version is simple. Choose the 413 for early RB correctness, smooth torque, and historically significant early hardware. Choose the 426 wedge when Street Wedge, Max Wedge, Super Stock, or period-performance identity gives it a real job. Choose the 440 when broad street torque, parts support, and general-purpose performance matter most. Same raised-deck family, three very different reasons to spend the money.

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Compatibility Notes

The RB family shares enough architecture to make interchange useful, but the raised-deck block, displacement-specific bores, year changes, balance differences, performance packages, and vehicle hardware still control what actually fits. The 413, 426 wedge, and 440 belong to the same tall-deck wedge family. That does not make every RB part universal.

• Keep RB and Low-Deck B Engines Separate
  The raised-deck 413, 426 wedge, and 440 are not low-deck 361, 383, or 400 B-series engines. RB intake manifolds are wider, and block height, valley width, pushrod length, some accessory relationships, and swap details differ. “Big-block Mopar” is not enough information to order an intake or plan a complete installation.
• The Three RB Engines Share Stroke, Not Bore
  The 413, 426 wedge, and 440 all use the 3.75-inch stroke, but their bores increase from 4.1875 to 4.25 to 4.32 inches. Pistons, rings, compression planning, valve clearance, head choice, and bore-specific rebuild parts therefore need to match the actual displacement.
• Rotating Assemblies Need to Match the Exact Engine
  Crankshaft, rods, pistons, compression height, damper, converter, flexplate, flywheel, and balance requirements need to be treated as a system. Shared RB architecture does not make every 413, 426, and 440 rotating part interchangeable.
• Later 440 Balance Hardware Needs Special Attention
  Forged-crank and cast-crank 440 combinations can use different balance arrangements. Later externally balanced engines require the correct damper, converter or flexplate, flywheel, and rotating components. Mixing earlier internally balanced assumptions into a later 440 can create a vibration problem before anything else has a chance to fail.
• The 426 Wedge Is Not the 426 Hemi
  The wedge and Hemi share displacement, not top-end architecture. Heads, pistons, valvetrain, intake, exhaust, block details, oiling expectations, and build logic are different. Hemi parts do not become compatible because both engines say 426.
• Cylinder Heads Can Cross More Easily Than Intakes, but They Still Need Checking
  RB and related Mopar wedge heads may physically share useful interchange, but chamber volume, valve size, port design, compression, piston clearance, exhaust fit, year, and intended application still matter. A head that bolts on can still be wrong for the combination underneath it.
• Compression, Pistons, Heads, and Camshaft Must Be Planned Together
  Do not copy a 440 piston plan onto a 413, use Max Wedge cam assumptions on an ordinary 426, or install later heads without checking chamber volume, deck clearance, quench, valve clearance, compression ratio, fuel, and intended use. Cubic inches do not repair a mismatched combination.
• Max Wedge Hardware Is Package-Specific
  Genuine 413 and 426 Max Wedge combinations use specialized heads, induction, exhaust, carburetion, compression, camshaft, linkage, air-cleaner, and application hardware. Individual pieces may fit other RB engines, but that does not make the resulting combination a factory Max Wedge package or automatically make it suitable for ordinary street use.
• 413 Long-Ram Hardware Needs the Complete Installation Considered
  Chrysler long-ram systems involve more than the intake castings. Carburetors, linkage, balance-tube details, air cleaners, brackets, exhaust, hood and brake clearance, and service access all need to match the vehicle and exact setup.
• Passenger-Car, Truck, Motorhome, Marine, and Industrial Hardware Can Differ
  Heads, manifolds, oil pans, mounts, cooling pieces, water hardware, governors, carburetion, accessory drives, flywheels, converters, and balance parts can change with application. A work-duty 413 or motorhome 440 may be a useful engine without being a complete passenger-car swap package.
• Transmission Fit Requires the Complete Crank-and-Drivetrain Combination
  Verify crank flange and register, bellhousing or transmission case, converter, flexplate, flywheel, clutch hardware, starter, linkage, kickdown, mounts, driveshaft, rear gearing, and balance requirements together. The general Mopar big-block pattern gets the conversation started. Year and hardware finish it.
• Induction and Exhaust Must Fit Both the RB Engine and the Vehicle
  Factory four-barrels, long-ram systems, Max Wedge cross-rams, aftermarket intakes, carburetors, exhaust manifolds, headers, downpipes, linkage, air cleaners, steering clearance, brake clearance, starter access, and hood clearance all depend on the exact engine and chassis.
• Mounts, Oil Pan, Cooling, and Front Dress Follow the Installation
  Motor mounts, oil pan, radiator capacity, water pump arrangement, pulleys, brackets, accessory drives, fan position, throttle linkage, steering, torsion bars, brake booster clearance, and driveline strength all need to be checked around the vehicle. A complete RB engine can fit the family and still refuse to fit the car.

That is the RB compatibility rule: identify the exact 413, 426 wedge, or 440 first, then match the bore-specific parts, rotating assembly, balance hardware, heads, induction, transmission, cooling, accessories, exhaust, and vehicle hardware around that engine. The RB family offers plenty of useful interchange. It does not offer permission to treat every tall-deck Mopar part as the same part.

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Common Family Problems

The RB family does not carry one fatal flaw waiting to punish every 413, 426 wedge, and 440. Most trouble comes from a less exciting list: age, heat, worn valvetrain parts, leaking seals, hard service, race use, incorrect balance hardware, and decades of rebuild work performed by people whose enthusiasm sometimes arrived before the micrometers.

That matters with RB engines because many of them were never asked to live easy lives. Some hauled enormous Chryslers. Some towed. Some pushed motorhomes. Some went racing. Some did several of those jobs before landing under a tarp where the current owner was assured it was “rebuilt not long ago.”

• Oil and Gasket Leaks
  Valve covers, intake and valley areas, timing covers, oil pans, rear main seals, fuel-pump areas, and other old gasket surfaces are common leak points. Hardened seals, distorted covers, crankcase pressure, rough sealing surfaces, overtightened fasteners, and repeated previous repairs all contribute. Old Mopar iron is allowed the occasional damp gasket. It does not need to leave enough evidence on the driveway for investigators to follow it back to the garage.
• Valvetrain and Rocker-Shaft Wear
  Shaft-mounted rockers are one of the RB family’s strong features, but shafts, rocker arms, pushrods, lifters, cam lobes, valve springs, guides, and the oil supply feeding all of them still wear. Sludge, restricted oiling, tired parts, excessive spring pressure, poor geometry, and mismatched rebuild pieces can leave the top end noisy, weak, or rapidly chewing itself up. A valvetrain that sounds like hardware being shaken in a coffee can is not displaying vintage character.
• Cooling-System Neglect and Heat Damage
  Weak radiators, clogged passages, tired water pumps, poor fan or shroud arrangements, incorrect pulleys, lean mixtures, and bad ignition timing can make any RB run hot. Truck, motorhome, police, marine, towing, and heavy-car engines deserve extra suspicion because sustained load creates heat whether the brochure called the engine heavy duty or not. Corrosion, damaged gasket surfaces, cracked heads, worn cylinders, and years of overheating do not disappear because the block still says 440.
• Wrong Balance Hardware
  The crankshaft, damper, converter, flexplate, flywheel, and the rest of the rotating assembly have to follow the same balance plan. This becomes especially important with later 440 cast-crank and externally balanced combinations, but any rebuilt RB deserves verification before the starter turns. Parts that bolt together can still produce vibration, bearing stress, cracked components, and a fresh engine that behaves as though it is trying to climb out of the mounts and return itself.
• Hard-Service and Race-Use Wear
  Some 413s spent decades in trucks, motorhomes, industrial equipment, and other jobs where the throttle stayed open long enough to earn overtime. Some 426 wedges lived competition lives involving high rpm, hard launches, and owners who considered teardown intervals part of normal maintenance. Plenty of 440s towed, hauled, idled under load, raced, overheated, or survived several owners who treated oil changes as suggestions. Worn bores, tired rings and bearings, cracked decks, damaged threads, worn lifter bores, sleeves, repaired blocks, and stressed heads can all hide inside an engine that looks impressively complete.
• Old Rebuilds and Mixed Internal Parts
  RB engines have been bored, decked, re-headed, re-cammed, re-pistoned, swapped, raced, repaired, and rebuilt for more than half a century. Wrong compression combinations, excessive overbores, poor machine work, mystery camshafts, mismatched heads, altered decks, replacement pistons, and mixed rotating assemblies can create weak compression, oil-control problems, vibration, overheating, and short engine life. Orange paint costs considerably less than good machine work, which explains why so much of it has been used.
• Compression, Fuel, and Detonation Problems
  Early performance RB combinations can carry enough compression to demand more from modern pump fuel than the owner expects. Later engines can have the opposite problem: low compression, large chambers, replacement pistons, or mixed parts that leave plenty of cubic inches but not much cylinder pressure. Add excessive timing, heat, carbon, poor quench, or a lean mixture and the result can range from lazy performance to destructive detonation. The number 440 on the block cannot negotiate with octane.
• Work-Duty Hardware Masquerading as Performance Hardware
  Truck, marine, motorhome, police, and industrial RB engines can be excellent cores, but they may carry different pans, cooling systems, manifolds, accessories, compression, camshafts, converters, flywheels, and service history from a passenger-car performance engine. None of that makes the core bad. It does mean a motorhome 440 does not become a Road Runner engine merely because somebody removed six feet of cooling hose and painted the air cleaner.

Most RB problems are therefore inspection problems before they become engine problems. Find out where the engine spent its life, determine which rotating assembly and balance system are actually inside it, inspect the valvetrain and cooling system, and assume an undocumented old rebuild deserves verification rather than gratitude.

The 413, 426 wedge, and 440 earned a reputation for being tough. Tough means they survived a lot of abuse. It does not mean the next owner gets all of those miles back for free.

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Common Family Misconceptions

The RB family is simple enough until somebody recognizes a displacement and decides the rest of the identification can be handled by reputation. The 413, 426 wedge, and 440 share raised-deck Chrysler architecture. They do not share one identity, one performance package, or one universal pile of parts.

• “All RB engines are basically 440s.”
  No. The 413, 426 wedge, and 440 share the raised-deck RB family and 3.75-inch stroke, but bore size, displacement, pistons, compression, heads, induction, application, balance requirements, history, and value can differ. Family resemblance gets the parts book open. It does not finish the order.
• “B and RB big blocks are basically interchangeable.”
  They are related Mopar big-block families, not one block with two names. RB engines use the taller raised deck, which changes intake width, valley geometry, pushrod length, rotating-assembly relationships, and some application hardware. A 383 intake does not become a 440 intake because both people at the counter said big-block.
• “Any Mopar 426 is a Hemi.”
  No. Chrysler built both the 426 wedge and the Gen II 426 Hemi. They share displacement, not cylinder-head architecture, induction, valvetrain, exhaust, parts requirements, factory role, or value. If the price says Hemi, the hardware had better say it too.
• “Every early RB performance story means Max Wedge.”
  No. The 413 and 426 Max Wedge packages were specific factory performance combinations. Regular passenger-car engines, Chrysler 300 ram-induction packages, Street Wedges, Max Wedges, and Super Stock hardware are different stories. Heads, compression, camshaft, intake, carburetors, exhaust, dates, application, stampings, and documentation have to establish which one is actually there.
• “Stage II, Stage III, ram induction, or extra carburetors prove the engine.”
  Hardware can support a claim; one impressive part does not establish it. Cross-rams, long rams, dual quads, heads, air cleaners, linkage, and reproduction pieces have been swapped around for decades. Correct package claims require the complete combination and the vehicle history to agree. Aluminum is evidence only after it proves where it came from.
• “Every 440 is a factory performance engine.”
  No. Chrysler built 440s for luxury cars, ordinary big cars, police duty, towing, marine use, motorhomes, and later emissions-era service as well as Magnum, Super Commando, TNT, HP, Six Pack, and Six Barrel applications. A plain 440 can be an excellent engine. It does not become factory muscle-car hardware because the air cleaner learned new vocabulary.
• “A truck or motorhome RB is basically the passenger-car version.”
  Not necessarily. Work-duty engines can carry different compression, camshafts, heads, manifolds, oil pans, mounts, cooling pieces, accessories, governors, converters or flywheels, and years of heavy-service wear. A sound work engine can make a useful core. It does not arrive dressed for a Road Runner, Chrysler 300, or Max Wedge restoration.
• “The 413 is obsolete and the 426 wedge is only interesting because of the Hemi.”
  Wrong on both counts. The 413 established the RB family and has legitimate Chrysler, Imperial, letter-car, and Max Wedge history. The 426 wedge carried the factory drag-racing program forward before the Hemi took the spotlight. The 440 may be the easiest familiar street answer, but later fame does not erase earlier engines that were important on their own terms.
• “The 440 is always the smartest RB build.”
  Not automatically. The 440 offers displacement, torque, broad support, and familiar street combinations, but originality, vehicle, budget, available parts, and intended use still decide the best engine. A correct 413 or documented 426 wedge may belong exactly where it is. Bigger numbers do not get veto power over the rest of the car.
• “Paint, decals, and dress-up parts prove what it is.”
  Orange paint proves somebody owned orange paint. Air cleaners, valve covers, intake manifolds, carburetors, and decals can all be changed. Displacement, factory package, HP status, Max Wedge identity, and originality need castings, stampings, measurements, dates, application evidence, and documentation. The shiny parts may start the story. They do not get to testify alone.

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Bottom Line

The Mopar RB-series is Chrysler’s raised-deck big-block wedge family: 413, 426 wedge, and 440. These engines earned their reputation with displacement, torque, durability, and enough factory performance history to make a heavy Mopar remember what the rear tires are for. They are not low-deck B engines, they are not Hemis, and “big-block Mopar” is not enough information to start ordering parts.

The three siblings have very different jobs. The 413 is the early foundation, equally comfortable being remembered for big-car authority, letter-car performance, or genuine early Max Wedge nastiness when the hardware proves it. The 426 wedge is the short-lived performance middle child whose biggest problem is sharing a number with the Hemi; a real Max Wedge deserves serious respect, while an ordinary 426 wedge deserves to be judged without somebody whispering “Hemi” into the price. The 440 is the broad-use bruiser: more common, more practical, and usually the easiest RB to justify when big street torque is the assignment.

For a restoration, keep the engine the car actually deserves. A correct 413 or 426 can be more important than swapping in a 440 simply because the bigger number gets more applause. For a performance build starting from loose iron, the 440 usually makes the strongest general-purpose argument because displacement, familiarity, and parts support are already working in its favor. Genuine Max Wedge hardware is a different conversation entirely and should be preserved rather than casually converted into somebody’s weekend experiment.

The expensive mistakes happen when reputation replaces identification. A 440 badge does not prove an HP engine. A 426 casting does not grow Hemi heads when nobody is looking. Max Wedge language does not turn ordinary parts into race hardware, and orange paint has never added compression. Early versus late, ordinary versus performance, original versus swapped, street versus marine or motorhome history, and even balance requirements can change what the engine is worth and what belongs behind it.

So choose the RB that fits the actual job, verify valuable claims before paying for them, and judge every core by condition rather than family mythology. The 413 started the raised-deck story, the 426 wedge gave it some of its sharpest teeth, and the 440 became the big production hammer most people remember. All three can be excellent Mopar engines. The trouble starts when every tall-deck wedge in the garage gets promoted to the most expensive story somebody can pronounce.

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