Chevy Big-Block Engine Parts Interchange: The Ultimate Guide to Sourcing and Selecting Compatible Factory Parts

By John Baechtel

Throughout their impressive production run, the Chevy big-block engines underwent many generations of updates and improvements. Understanding which parts are compatible and work best for your specific project is fundamental to a successful and satisfying Chevy big-block engine build. Learn Chevy big-block engines and their various components like never before with definitive answers to tough interchange questions with clear instructions.

• Language: English
• Publisher: S-A Design
• Release date: Apr 15, 2014
• ISBN: 9781613251812

Book preview

INTRODUCTION

Big-block Chevys are among the most prolific and widely used racing and high-performance engines in the world next to the renowned Chevy small-block. The small-block Chevy was already nicknamed the mouse motor, so it was only logical that its bigger brother was ultimately christened the rat motor. Some insist that rat motors are equally significant and they’ll find no argument here. Few would dare to question the legendary big-block’s position in the hierarchy of high-performance engines. In many cases they dominate classes in which small-blocks are incapable of providing the brute torque and horsepower required. While competing brands also manufactured historically significant big-block engines, none except the Chrysler Hemi has maintained the longevity and sterling performance record established by Chevrolet big-block V-8s. Indeed the Hemi is the only other original legendary engine package still available (albeit in crate engine form only), but not to the extraordinary degree of production use established by Chevrolet’s brutally powerful big-blocks.

The 350-hp L34 396...

The 350-hp L34 396 (1966–1969) was a strong player with a forged-steel crank, high-lift hydraulic camshaft, Holley 4-barrel (1966–1968), and 25 hp more than the standard 325-hp L35 version used in Camaros, Novas, and full-size cars through 1972. (Photo Courtesy Tom Dufur)

Chevrolet big-blocks still power Chevrolet trucks nearly 50 years after their debut. The last Gen I Hemi-powered production vehicle went off the market in the mid-1970s. Meanwhile Mark IV Chevy big-blocks are still going strong. They were designed to be bigger, tougher, and more powerful. Canted-valve free-breathing porcupine heads are their primary performance feature, but they were also built with strength, durability, and high-performance in mind. To this end they incorporated thicker cylinder walls, bigger mains, forged cranks and rods, forged pistons, big valves, solid lifter cams, and aluminum intake manifolds; it’s a proven recipe for building high-performance large-displacement big-blocks that mean business.

This ground-pounding Reher..

This ground-pounding Reher-Morrison big-block raised the world wheel-driven piston-powered land speed record to more than 414 mph with carburetors and nitrous oxide injection.

Mark IV big-blocks were first...

Mark IV big-blocks were first delivered in 396- and 427-ci versions. With Mark II–based canted-valve heads the name porcupine head was coined early, but eventually faded; the engines simply became known as big-blocks or rat motors. (Photo Courtesy GM Media Archive)

The 360-hp LS5 454 came in Monte...

The 360-hp LS5 454 came in Monte Carlos and Chevelles with a steel crank, hydraulic cam, high-lift hydraulic camshaft, dual exhaust, cast-iron oval-port heads, and two- or four-bolt mains. The same engine was rated at 390 hp in Corvettes. (Photo Courtesy Tom Dufur)

Big-blocks have evolved into...

Big-blocks have evolved into the ultimate form of doorslammer drag racing with the DRCE (Drag Race Competition Engine) that continues to dominate Pro Stock racing. No interchangeable parts here, but solid big-block heritage nonetheless. (Photo Courtesy JEGS)

Big-block Chevys remain the predominant power plant in Pro Stock and Pro Mod drag racing, but have never seriously challenged the Chrysler Hemi in the higher fuel and alcohol classes. By the time the big-block came about, racers had already embraced the Hemi in these classes. A few big-blocks were run in the Top Fuel and Funny Car ranks, but early teething problems caused racers to abandon them in favor of tried-and-true Hemi power plants that were already well developed for the unique stresses of the fuel racing environment.

Nonetheless the big-block has dominated sportsman drag racing classes nearly as much as the small-block Chevy and it is pretty much the default performance engine choice for general marine applications including drag boat and offshore powerboat racing. The big-block was groomed as the performance engine for the legions of loyal followers who would rather race than watch; hence Chevrolet never entertained the possibility of its use in fuel racing.

Big-blocks are dominant in tractor pulling and they have been used in aviation applications and road racing; they are used much less frequently in off-road competition. It is one of the primary choices for bracket and sportsman drag racing and is second only to the small-block for most high-performance street applications. The amazing proliferation of the Chevy big-block reinforces the integrity of the design philosophy and in some respects the historical relevance of its esteemed predecessor, the legendary Mark I big-block 409.

CHAPTER 1

FORMIDABLE FORERUNNERS

Chevrolet manufactured two significant big-block engines in the second half of the twentieth century. It’s important to acknowledge and briefly examine them because the first-design big-block became a strategic player in the epic power struggle that erupted among domestic automakers in the early 1960s. It set a compelling performance precedent for the second-generation Mark-series big-block engines. I refer of course to the Mark I Chevrolet W engine, a celebrated engine in its own right. This unique design, introduced in 1958, provided a smooth-idling high-torque engine for GM trucks and the larger, heavier, and more glamorous cars that the public demanded. Big cars implied elevated status. Everyone wanted one, but the early small-block still displaced only 283 ci and could not provide enough torque to move these bigger cars efficiently. Enter the first Turbo Thrust 348 W engine, which also significantly boosted the performance of Chevrolet and GMC trucks.

The Chevrolet Mystery Motor was...

The Chevrolet Mystery Motor was designed and built in relative secrecy to compete on the high banks of Daytona International Raceway and other high-speed venues. Although rated the same as the earlier W engines, its all-new design was far more powerful and capable of more than 175-mph speeds while competitors were stuck in the 150- to 160-mph range. The Mystery Motor was the prototype for all subsequent Mark IV and later big-block Chevys. (Illustration Courtesy GM Media Archive)

W-series Mark I (Gen I) engines are the original Chevrolet big-blocks, built to power passenger cars and trucks across the Chevrolet lineup. They featured an overhead design with offset valves and the unique scalloped valve covers that prompted the W moniker. They were produced from 1958 through 1965 in three different displacements. The original 348-ci (5.7L) engine was offered from 1958 through 1961 in cars and through 1964 in trucks. In 1961 the engine gained 61 ci, becoming the fabled 409 (6.7L) celebrated in song by the Beach Boys. (Who doesn’t remember She’s real fine, my 409? Every teenage driver in America coveted the 409.) The 409 was offered from 1961 through 1965 and was briefly supplemented by the one-off 427-ci RPO Z11 race engine available only in 1963. The original Chevrolet engineers have long lamented some of the design compromises inherent to the W engines and they labored to bring them up to speed. In some cases, inefficient combustion chambers, valve sizes, and cooling problems on some 348 versions limited performance. Despite numerous problems, these engines ultimately fulfilled their performance potential by moving to the nation’s drag strips and selected deserted roads during their brief, but surprisingly influential, tenure.

These first-generation big-blocks were built on 4.84-inch bore centers with two-bolt main bearing caps and interchangeable cylinder heads. Performance 409- and 427-ci versions incorporated larger ports and valves than the standard 348 and 409 base engines used in cars and trucks. All engines in this series incorporated a main oil gallery just above the oil pan rail on the driver’s side of the engine block (the same as on early Mark IV series V-8s). All W-series engines, including the fabled 427-ci Z11 package, have two-bolt main caps. One quick way to differentiate between 348s and 409s is by dipstick location; it’s on the driver’s side on all 348s and on the passenger’s side on 409s and the Z11 race engine.

The 409 was available only...

The 409 was available only in full-size cars, including convertibles. Internal components included a forged crank, rods, pistons, and high-flow cylinder heads. In addition to the 425-hp twin-carb engine Chevrolet offered multiple single 4-barrel versions ranging from 340 to 409 hp. (Illustration Courtesy GM Media Archive)

W-series cylinder heads exhibit several distinct characteristics including offset valves (not inline) and unique if not downright odd wedge-shaped combustion chambers that incorporate part of the upper cylinder wall. The block deck surfaces are not perpendicular to the cylinder bores. This results in a uniquely beveled piston crown with a pronounced quench area intended to promote good mixture turbulence with a spark plug positioned to provide a fast burn. The resulting high brake mean effective pressure (BMEP) for that period at low engine speeds delivered a broad torque curve that provided exceptional performance in larger and heavier cars and trucks.

Mark IV and later production engines have no commonality with W engines except that original Mark IV blocks (or later Bowtie blocks) with one-piece rear seals accept W-series crankshafts if spacer bearings are used to accommodate the difference in main bearing size.

Zora Arkus-Duntov (legendary Corvette designer and father of the GM performance culture) christened them Mark I engines to differentiate them from later-design big-blocks because he was still working on W-engine drag racing development while the all-new Mark II Mystery Motors and subsequent Mark IVs were in the design stage. The first-design Mystery Motor (there were actually three versions) incorporated the 409-ci W-engine bore and stroke and the 427-ci Z11’s 6.135-inch rod length, all wrapped up in a brand-new cylinder block designed to accept the new canted-valve heads. If you know your history, it’s easier to follow Mark IV and later engine progression.

From a performance standpoint nearly all W engines were rated at more than 300 hp. Among the 348 offerings were four Tri-Power versions delivering 280, 315, 335 hp, and the best of the bunch with 350. Many 409 engines were offered, ranging from a 360-hp single 4-barrel unit to a 425-hp dual 4-barrel powerhouse.

The special 427-ci RPO Z11 race version (1963 only) was rated at 430 hp with a longer 3.65-inch stroke, 13.5:1 compression ratio (CR), and dual Carter AFB carbs similar to the 425-hp versions. Records suggest that this engine actually delivered more than 500 hp and was installed in approximately 50 factory-built Z11 race cars. Twenty partial engines were also produced for replacement purposes and they are nearly impossible to find today.

These Gen I or W-series engines provided a formidable performance stepping stone from the small-block V-8 to the Mark IV big-block engine. Today, the same bore spacing and beefy architecture prevails with basic dimensions that allow big-blocks to be built with stroke lengths ranging all the way to 4.75 inches and in some cases even longer. Performance big-blocks and their spectacular racing history reinforce the performance legacy of the original W engines, whose accomplishments on the drag strips and banked ovals in the early 1960s established an impressive Chevrolet stronghold on motorsports activity in the United States.

Gen II, the Mark Series

The Mark II second-generation big-block began life in the summer of 1962 under the direction of Chevrolet engineer Dick Keinath. It has often been called an upgrade or a revision of the W engine, but that is incorrect. The Mark II was a clean sheet racing engine design that only incorporated a few remotely related design cues from earlier W-series engines. Among them the same 4.84-inch bore center dimension, the main oil gallery location adjacent to the driver-side oil pan rail, race-style Moraine M400 aluminum bearings from the 409, and the basic 409 crankshaft. Initially it was an all-new 409-ci engine designated the Mark II to clearly differentiate it from earlier W-series engines. The old saying that racing improves the breed definitely holds true for the big-block Chevy.

The Mark II (RPO Z33) V-8 was designed for racing on high-banked NASCAR tracks where top speed is paramount, but designers knew from the very beginning that this engine would ultimately power the next generation of Chevrolet trucks and passenger cars, so parallel development was carried out from day one. It is interesting that Mark II development engineer Billy Howell says that he has never heard of the RPO Z33 designation and is not confident about where it came from. It may be legit or it may be part of the unverified nostalgic lore that surrounds these remarkable engines.

This engine was destined to set the stock car world on its ear with its debut at the 1963 Daytona 500. A Ford ultimately won the race that year, but the mind-blowing speeds recorded by Junior Johnson, Johnny Rutherford, Smokey Yunick, Ray Fox, and Bubber Farr stunned the competition. Junior Johnson qualified on the pole thanks to blistering speed and served notice to the competition that Chevrolet was in the house with a Mystery Motor designed to tear them a new one.

The big secret of the mysterious engine was its cylinder head design. It had unique offset canted valves that opened away from the cylinder walls to improve cylinder filling by unshrouding the valves. It was called the porcupine because the valvestems appeared to stick out in all directions much like the quills on a porcupine. The chamber-in-block design of the W engine favored low- and mid-range torque production, but lost efficiency at higher engine speeds, particularly at racing RPM.

A more conventional bathtub chamber with unique compound valve angles provided superior high-speed breathing and efficiency to support the racing effort. They effortlessly served the desired low-speed performance with higher CRs and revised inlet and exhaust tuning. By incorporating Chevrolet’s trademark stud-mounted rockers the canted valves were easily activated by unequal-length pushrods that remained stable at racing speeds. Spark plug location was revised with an angle plug design entering the cylinder tangentially. This further improved high-speed combustion efficiency and eliminated the need for the W-style valve covers to accommodate spark plug placement on earlier engines.

According to Smokey Yunick, at least 50 of the original Mark II engines were built, this statement seems entirely plausible given in-house testing requirements and additional outside development performed by racers including Smokey and Junior Johnson. Howell concurs with Smokey’s assessment; nevertheless, few can be found today.

In 1963, Chevrolet initiated a Mark II design study as part of the second-generation passenger car and truck Mark engine development. This study briefly surfaced as a Mark III big-block design using wider bore centers to accommodate larger cylinder bores and larger valve sizes along with more favorable intake runner positioning and port entry angles. In the end this project never materialized because tooling costs for the new block and accompanying hardware were deemed excessive. If the design had flourished, subsequent big-blocks may well have been even more powerful. As it was, the basic Mark II architecture was refined for road use and launched into production in 1965 as the Mark IV 396-ci engine; the top power rating was 425 hp.

Except for displacement the Mark IV remained relatively unchanged for the next 25 years. It established itself as the most respected large-displacement performance engine for racers, rodders, and towing applications. Ironically, decades later, private big-block race engine developers, such as Sonny’s Racing Engines, adopted wider bore spacing and complementary heads for their Pro Mod race engines and realized the significant power gains some Chevrolet engineers had envisioned back in 1963.

The new Mark IV big-blocks had some component-similarity with previous W-series engines. Among the shared features were an appropriate mix of cast and forged pistons per specific horsepower requirement and the surprisingly useful crankshaft compatibility. All Mark IV big-blocks have 2.75-inch main journals with production stroke lengths ranging from 3.76 to 4.25 inches. Shorter-stroke Mark IV engines can be built (or destroked) using earlier 348 or 409 forged crankshafts with appropriate spacer bearings.

This little-known direct swap was first adopted in the early days of 500-ci Pro Stock racing as racers explored big-bore short-stroke combinations. No longer used for that application, this swap is still employed in selected drag racing classes. It is particularly popular at Bonneville, where superior-breathing Mark IV big-blocks are sometimes destroked with forged W-engine cranks to build high-RPM small-displacement big-blocks that breathe like crazy to meet particular class displacement limits.

Designer Dick Keinath sets the record straight by confirming that only the crankshaft in the Mystery Motor interchanges with the W engines or Mark IV big-blocks. Although the engine is visually almost identical to the Mark IV series it spawned, Keinath relates that port locations and alignment are different, bolt hole locations are not the same, and some cooling passages are not the same. During its concurrent development, the Mark IV engine underwent numerous revisions to accommodate manufacturing and production requirements.

Basic Engine Architecture

The Chevrolet Mark-series big-block is a traditional V-8 with unique design features. It is not based on the earlier 348/409 W-series engines, but it does incorporate some minor design cues from both. As such, it is possible to fit earlier W-series crankshafts into Mark IV blocks to achieve small-displacement destroked engines for favorable class placement in some racing series. Mark-series V-8 architecture incorporates two banks of four cylinders set at an opposing angle of 90 degrees. The bore spacing between cylinders measures 4.84 inches on centers, and the deck surfaces remain a conventional 90 degrees perpendicular to the centerline of the cylinder bores. The crank centerline is set at the bottom of the block almost even with the oil pan rails as it is on the small-block and previous W-series engines.

The standard engine’s deck height measures 9.80 inches from the crank centerline to each deck surface. Tall-deck truck versions measure 10.2 inches to accommodate taller pistons with one additional compression ring added to promote stability and enhance cylinder sealing. The canted-valve cylinder heads are the main feature of these engines and the reason they breathe so well in performance applications. The offset canted-valve placement requires separate pushrod lengths for the intake and exhaust valves. All engines use 6.135-inch connecting rods that yield a range of rod-to-stroke ratios from 1.53 to 1.63 depending on deck height, stroke length, and pin height. All Mark IV and later big-blocks have 2.75-inch main journals and 2.2-inch rod journals. General engine construction is robust and these engines typically have no problem revving to high RPM with appropriate valve gear. The cranks are tough too; the mains are beefy and the cylinder heads promote stump-pulling torque and serious power when properly matched to the engine application.

Regardless of whether you build...

Regardless of whether you build your engine from individual parts or install a crate engine it is almost certain to contain a good mix

Reviews for Chevy Big-Block Engine Parts Interchange

[amyrph · Rating: 4 out of 5 stars]

Got this as an early review edition. I was interested in it because a friend of mine and I are working on rebuilding a 1970 pick up truck. The book is very informative and helpful and we will put it to good use. Writing is clear and easy to follow.

[dede1007 · Rating: 5 out of 5 stars]

This is a great go to book for the guys OR gals in your life that are into rebuilding big blocks. It has great photos and easy to follow instructions. Even for beginners who don't know a lot about big blocks.

[p.e.b. · Rating: 5 out of 5 stars]

Chevy Big-Block Engine Parts Interchange: The Ultimate Guide to Sourcing and Selecting Compatible Factory Parts by John BaechtelTo all big-block, muscle car or racing guys, this is the book for you! This in depth guide contains all the information necessary to restore or build your Chevy. Included are clear photographs of engines and engine parts, factory part numbers, and more. The Source Guide at the back of the book plus the chapters on Parts Resources and Aftermarket Replacement Parts tell you where to purchase engine parts. The author is very knowledgeable and covers everything from the basics to the details of Chevy big block engines. I highly recommend this very informative, well-written book. You will refer to it time and again.

[kooltrek · Rating: 4 out of 5 stars]

This is a great book if your looking to restore a Chevy big-block or to build one from scratch. This book gives you great pointers and tells you very clearly which parts are compatible with which engine. It tells you if you want new or restored parts and has very clear instructions and good pictures. Regardless if your restoring a big-block from 1970 or 2005 this is the book for you.

[patty1323 · Rating: 5 out of 5 stars]

My brother loved this book he said it was interesting and had easy to follow instructions.He said that the books by this company are the best he has ever read on working on your cars.He would recommend them to everyone.

[cherylefisher · Rating: 4 out of 5 stars]

I am not a mechanic, but my husband has restored his 1985 Chevrolet Blazer using a short block engine. I won this book from the Early Reviewers and found it to be beyond my comprehension so I had my husband review it. He thought it would be extremely helpful to the mechanic or backyard mechanic looking to build or rebuild a big-block engine.

[dbettenson_1 · Rating: 5 out of 5 stars]

Great photos, easy to follow charts and info. Anyone interested in big block motors will devour this book!!!! My husband, myself and my son and others loved this book!!!!

[robtcm · Rating: 5 out of 5 stars]

An extremely well presented book. Very detailed, carefully researched and well written. Plenty of very useful information complete with charts and great photography. A must-have manual for anyone working with Chevy Big Block engines. Highly recommended!