Aftermarket big-block cylinder heads offer numerous advantages over factory steel units. F
When it comes to bang for the buck, it's hard to beat a big-block Mopar. The wedge engine (named for its wedge-shaped combustion chamber) is a great combination of torque and horsepower and responds well to modifications. in production from the mid-'50s to the late-'70s, wedge engines were used in cars, trucks, and even motor homes, so finding one to build is usually as close as your nearest auto salvage yard. Another great thing about the wedge-it's an easy swap into any B- or C-body car that originally had a V-8, so it's common to see Satellites and Coronets with a 440 replacing their original 318. With kits available from several aftermarket companies, the big-block can also be swapped into slant six and A-body cars with minimal headache. While the big-block Mopar powerplant responds well to cam swaps, intake and exhaust modifications, and is capable of some pretty serious power with factory heads, the proper aftermarket heads could optimize your combination and shave a few pounds from the front of your car, but how do you choose the right head for your build? With so many factory and aftermarket cylinder head options, there is certainly an ideal head for your application. The trick is to pick the cylinder head that best fits your combination and meets your needs for horsepower, weight, and budget.
When Chrysler engineered their wedge heads in the '50s, they were lighter and more economical to manufacture than the first-generation Hemi cylinder heads. The early wedge heads had small valves and inefficient combustion chambers, but with the popularity of racing in the early '60s, the engineers at Chrysler pooled their resources to design the Max wedge cylinder head. Max wedge heads had larger ports and bigger valves than previous wedge heads. motors with these heads dominated drag racing and did well in other forms of motor sports until the re-introduction of the Hemi in 1964.
While the Max Wedge head is a great option, don't plan on using a set of these factory heads for your build. Factory Max wedge heads bring top dollar for restorations or Stock class drag racing applications and are scarce, so they're really not a viable option for the average street/strip engine.
With so many factory castings around and an endless supply of aftermarket options, which head is the best choice for your build? When we choose a cylinder head for one of our builds we first clearly define our goals. Is the car a street car, strip car, or will it serve dual purposes? Do we want the weight advantage of an aluminum head or the thermal advantage of a steel head? Are we going for all-out horsepower or will a factory head suffice? Most importantly, what is the budget for our build? Answering all these questions will narrow down the cylinder head choices for your project, but you may still find several heads that will satisfy your goals, then the choice is up to you.
The following cylinder head guide should help make the choice easier. Follow along as we describe and compare the popular factory heads, and let you know what is available from the aftermarket.
This picture shows the 915 casting number as well as the closed chamber design of these he
Factory Cylinder Heads
When comparing factory Chrysler big-block cylinder heads we can break them down into three basic categories: Max wedge, open chamber, and closed combustion chamber. We won't consider the pre-'64, non-Max-Wedge heads because the rocker shaft and bracket system they utilized is not compatible with modern valvetrain components. Max Wedge heads are easily identifiable by the lack of a heat cross-over passage, large 1.88-inch exhaust valves, and very large ports. Casting numbers for the Max Wedge heads end in either 286, 209, or 518; keep an eye out at the swap meets in the unlikely event you'll run across a set of these desirable heads. While the Max Wedge heads do offer great power potential, they are expensive and hard to find, so unless you're building a Stock or Super Stock class racer, or restoring a factory race car, the cost of these heads is prohibitive for the average build.
Closed Chamber Factory Heads
The closed chamber heads were manufactured and installed on pre-'68 vehicles; popular units have casting numbers ending in 915 or 516. These heads are easily recognizable by their closed, quench-style combustion chamber and are actually a good choice for a performance build. The Chrysler engineers knew the quench area of the combustion chamber was key to power production, and these heads utilize that theory very well. The main drawbacks of the closed chamber heads are relatively small 1.60-inch exhaust valves and the lack of hardened valve seats. An exception is the '67 440 HP 915 casting, which is the first big-block head to incorporate a 1.74-inch exhaust valve, making the '67 440 HP 915 a good choice for a performance build. In fact, an old racers' trick was to swap 915 heads onto a '68 440 HP, which netted some 13:1 compression! Of course, that would never work with today's pump fuels, but the combination does make great power if race fuel is utilized. Cylinder heads with the 516 casting number are virtually identical to the 915s, but were only produced with 1.60-inch exhaust valves.
While the combustion chamber of the closed chamber factory heads is well suited for power, there are some drawbacks to these cylinder heads. First, these heads were manufactured when there was plenty of lead in fuel to keep the valve seats lubricated, so the valve seats didn't need to be hardened. Running an engine with these heads on today's fuel can lead to valves, especially on the exhaust side, becoming recessed into the head, resulting in substantial power loss or even broken or dropped valves. Second, the exhaust valve size limits the flow of these heads and, thereby, also limits their power potential. To remedy these drawbacks, hardened seats and larger valves can be installed, which give these heads the flow potential of later castings and the ability to run on unleaded fuel while retaining the desirable closed combustion chamber. Another issue with any factory steel head is the shape of the valveguide and seat pocket, which limits valvespring choices. The only way to solve this problem is to machine the outside of the guides and the seat pockets to accommodate double or triple valvesprings. Add to the above operations the cost of porting these heads, and you can quickly have as much tied up in your steel heads as the cost of an economical set of aluminum units, so it's hard to justify the cost unless you're restoring a rare car or racing in a class that dictates a steel head.
Factory Chrysler big-block heads, such as the 915 and 452 castings shown here, are plentif
This picture shows the 915 casting number as well as the closed chamber design of these he
When the 915 head (right) is compared to the later 452 casting (left), the differences are
Factory steel heads offer decent performance in stock form, but really respond to port wor
Open Chamber Factory Heads
In 1968, Chrysler big-block cylinder heads were redesigned to be manufactured with an open-style combustion chamber. The engineers knew this was not the best power producing combustion chamber design, but foresaw tighter emissions standards and substandard fuel so the 906 casting was developed to take the Chrysler big-block into the future. Knowing the performance enthusiasts wouldn't like the new cylinder head design if it didn't make the power of the closed chamber designs, Chrysler decided to upgrade the open chamber heads with larger, 1.74-inch exhaust valves. Intake valve size remained at 2.08 inches. Designing pistons to reach the top of the cylinder (or above) in their performance models gave engines with the 906 heads similar compression ratios to engines with closed chamber heads. The 906 heads were used on every big-block engine between 1968 and 1971 and will make decent power in stock or ported form. After 1971, the casting numbers changed, but the overall design of the ports and the combustion chamber of the big-block head didn't. All of the post-'68 open chamber heads offer similar power potential and work equally well in a performance application.
The port size difference is apparent in this photo. The near head is an unported 915 casti
While the open chamber design limits the power potential of the post-'68 heads, these heads do offer the builder several advantages. These heads are a good alternative if compression ratio would be too high with a closed chamber design. Also, they came from the factory with 1.74-inch exhaust valves, so the extra expense of machining the seats and purchasing bigger valves is saved. It is recommended, however, to install hardened seats in the pre-'74 heads as they suffer from the same limitation as the closed chamber units. In our opinion, the best open chamber head is the 452 casting, which was produced from 1976 through 1978. These castings offer the same combustion chamber design, flow, and performance potential as the 906 castings, but they already incorporate hardened valve seats, making them very tolerant of today's unleaded fuels.
Aftermarket Cylinder Heads
If your combination requires more flow than a factory head can support, or if you desire the weight savings of an aluminum cylinder head, an aftermarket head is your only choice. Edelbrock, Indy Cylinder Head, Brodix, and Mopar Performance offer numerous choices that can accommodate your need for power as well as your budget. Choosing the right aftermarket head depends on what you wish to achieve from your combination. Placing a large port, high-flow race head on your stock 383 is not a good choice, and the results will probably disappoint you. Conversely, a budget aftermarket head will certainly restrict that big cubic inch race motor you're building, netting similar, disappointing results. In this section we'll outline aftermarket cylinder head selection by manufacturer and give you the lowdown on which head may be right for your combination.
Edelbrock Corporation has long been known for producing quality, affordable parts, so when they decided to produce their Performer RPM cylinder head for the big-block Chrysler we were certainly excited. These heads in stock form offer flow numbers comparable to ported factory heads, come completely assembled, are ready for cams up to .600-inch lift, and are priced reasonably. These heads come with large 1.81-inch exhaust and 2.14-inch intake valves right out of the box. Additional benefits are hardened valve seats and dry exhaust bolt holes meaning no more coolant leaks or messy sealer around the header bolts. These heads are completely interchangeable with factory units utilizing factory style rocker arms and valve gear that is oiled internally by the factory provision in the block. We saw a gain of more than 30 hp over fully prepped 452 castings by bolting a set of Performer RPMs to our 440 bracket motor, which was dyno tested in a previous issue. Comparing the cost of these heads against fully prepping a set of factory steel units really makes the choice a no-brainer.
Do Edelbrock's Performer RPM heads have you wishing they made a head with a little more potential? Rumor has it that Edelbrock will be releasing a Victor series head for the big-block Mopar that will offer flow and power potential similar to high-end race heads at a conservative cost. Watch for our upcoming engine challenge because at least one competitor has already decided to use the new Edelbrock Victors for his build!
Indy Cylinder Head
Most consider Indy Cylinder Head to be the premier supplier of high-performance, aftermarket Mopar cylinder heads. Their long valve, big port designs have the potential for huge power numbers, and we can attest to the performance and durability of their products. With several big-block heads to choose from, and several levels of porting available for each head design, we're sure Indy has a head that will work with your combination.
Indy's 440-EZ cylinder head is designed to be a direct replacement for a stock head. This head utilizes the long valve, high intake port volume design that made Indy famous, but unlike their 440-SR or 440-1 heads, the exhaust ports remain very close to the stock location. This head is a great choice for an A-body or any application where exhaust clearance is an issue. These heads utilize stock-style valve gear and oil internally like factory units so no external lines are required. The EZ head offers a large 2.19-inch intake and 1.81-inch exhaust valves and is available in either a 75cc closed or 80cc open chamber design. The chambers are heart-shaped and designed for maximum quench, giving this head the potential for 750 hp on a properly prepped engine. Like most Indy heads, the EZ is available as cast or fully CNC ported with Max Wedge size ports.
The Edelbrock Performer RPM cylinder head is a good economical choice for the big-block Ch
Right out of the box, the Edelbrock Performer RPM heads offer port size and volume similar
This Indy 440-1 cylinder head has been ported to Max Wedge size ports. Next to a fully por
Indy's 440-SR heads make great power as we've shown in our '68 Barracuda. Raised exhaust p
Indy's 440 SR head gives great performance for the dollar and is the head we utilize in ported form on our '68 Barracuda bracket car. This head also uses stock-style rocker arms, 2.19-inch intake and 1.81-inch exhaust valves, and the typical Indy heart-shaped combustion chamber in 75cc volume. Indy claims these heads to be good for 770 hp, but we've actually made nearly 800 hp with these heads. The 440-SRs are oiled externally via oil lines to the galley at the rear of the block, giving added area in the intake runners for porting. These heads do have raised exhaust ports so header clearance, especially in A-bodies, can be an issue.
The 440-1 cylinder head is the one that made Indy famous. Fully CNC ported to Max Wedge size ports, this head has the potential for 900-plus horsepower and will support engines up to 540 ci. Like the SR head, the 440-1 has raised exhaust ports and requires external oil lines for the rocker arms. The rockers are also specially offset to accommodate wider intake runners, meaning more power producing intake volume. The combustion chambers are heart-shaped and offer a 75cc quench design. For the money, this cylinder head package offers great power potential and is very durable. We've put nearly 1,000 trouble-free passes on a 540-inch wedge topped with these heads and can attest to their ability to provide reliable power.
If displacement of more than 572 ci and high horsepower is your goal, Indy's 572-13 or 600-13 cylinder heads may be in your future. These heads are designed to be the ultimate wedge head, offering normally aspirated power potential of 1,000-1,200 hp. Jesel rocker arms must be utilized with these heads, as well as valve covers with spray bars installed for rocker arm and valve train oiling. The 600-13 heads also require a special block with 4.840 bore centers to accommodate huge 2.40-inch intake and 1.94-inch exhaust valves. we just finished installing the engine in a '71 Duster bracket car and plan to test it in the near future, so look for a 572-inch wedge/572-13 head build in an upcoming issue.
All of Indy's heads, like the 440-1 shown here, utilize a heart-shaped, quench-style combu
All Indy heads, except the 440-EZ, utilize external oiling of some kind. The SR heads and
This picture shows the difference in offset of the 440-1 Indy rockers (bottom) and standar
The Brodix B1 line of cylinder heads are proven power makers. We utilized this set of B-1
B1 Heads do require special rocker arms, but the BS units (shown here) utilize standard in
We've found the B1 BS heads to be reliable power makers in both street/strip vehicles and
Mopar Performance is the original supplier of aftermarket go-fast goodies for your Chrysle
Brodix Cylinder Heads
The B1 BS head was designed as a direct replacement for the Mopar factory steel head. These heads do require special rocker arms and longer pushrods, but are oiled internally like factory heads. Standard big-block intakes, headers, and valve covers are compatible with these cylinder heads. These heads offer a well designed quench-style combustion chamber and large 2.20-inch intake and 1.81-inch exhaust valves. We utilized a ported set of these heads on a 499ci race wedge and had no trouble getting our '91 Daytona into the 8s.
The original B1 cylinder head for the big-block Mopar has earned a reputation for the ability to make high horsepower. Large 2.30-inch intake and 1.78-inch exhaust valves, combined with intake flow in excess of 400 cfm, combine to make these aluminum heads serious performers. however, these units are not intended to simply bolt-on to your big-block and require special pistons and rocker arms, as well as a special intake manifold. These heads have a thick deck making them a good choice for nitrous applications and are also available in a moved centerline version, ideal for large displacement motors.
Mopar Performance has long been supplying enthusiasts with parts and accessories to make their cars look and perform better than new. Their cylinder head selection is varied and incorporates everything from stock replacement heads to full blown, CNC ported race units. If you're looking for a factory replacement head or a legal stock class cylinder head, Mopar Performance can supply the part. Most of their cylinder heads require no modifications and utilize stock-style rocker arms and valve gear. Their Stage VI units are available in five states of finish from bare casting to fully CNC machined, and make good power on a street, strip, or full-blown race engine.
This cylinder head is an aluminum replacement unit for factory big-block heads. It incorporates 2.14-inch intake and 1.81-inch exhaust valves and is a closed chamber design. These heads weigh in at 25 pounds each, which is about half the weight of an iron head, and utilize all stock-style rockers, intakes, and exhaust manifolds or headers. Unlike Stage VI units, these heads do not require the use of intake manifold adapters.
These cast iron heads were designed to be replacements for '62-'64 Max Wedge units. They feature a large port on the intake side for improved flow and an improved short side radius on the exhaust side. The combustion chamber is a closed style, and unlike the early Max Wedge units, these heads utilize six-bolt valve covers. Valve sizes are either 2.08-inch intake and 1.88-exhaust, or the more conventional 2.14-inch intake and 1.81-inch exhaust. These heads are a great choice for a nostalgia racer and are also legal for stock and super stock class racing.
This Max Wedge replacement head is an excellent choice for the nostalgia, stock, or super
This Stage V cast iron cylinder head offers a blend of performance and streetability. It is an open chamber design similar to 906 castings, but outflows the 906 on both the intake and exhaust side. It's 96cc chamber is pump-gas friendly, and the head is available with the same two valve size configurations as the above Max Wedge replacement heads. Standard exhaust and intake patterns are used along with standard valve gear and valve covers. Intake rocker arms with a special offset must be used with these heads.
Stage VI Heads
With no less than seven versions of the Stage VI aluminum head displayed in their catalog, Mopar Performance shows they are dedicated to providing engine builders with a head that will meet their needs. These heads are available in bare form, allowing the engine builder to custom port the heads, or in several states of machining all the way up to fully CNC ported units. Port size as cast is either standard or Max Wedge size. The Stage VI heads will work on a healthy street motor, but really come into their own when utilized on high-compression, large ci race engines. They are a 78cc closed chamber design that incorporates 2.18-inch intake and 1.81-inch exhaust valves. The spark plug location is canted toward the exhaust valve to promote efficient combustion. Using these heads does come at a price, however, as offset rockers must be purchased to make them work. Certain Stage VI heads are designed to use an RB intake on a B block. Using a B intake on a B block or an RB intake on an RB block will require intake manifold spacers.
As you can see, no matter what the application, there is either a factory or aftermarket cylinder head that will meet the needs of your big-block Mopar. We hope our cylinder head guide is useful and directs you to the right choice given your horsepower needs and budget constraints. Now is a great time to be building a Chrysler wedge engine. During the past 20 years, the aftermarket has gone from nonexistent to overflowing with support for the big-block Chrysler.
This year's engine challenge features the RB wedge engine, and we're eager to see what cylinder heads our contestants will use on their entries. Follow along, as we're sure the power numbers will be impressive!
We've used aluminum Stage VI heads on bracket engines with some success, but have found th
If you're planning to run Stage VI heads on an RB block, or on a B block with a B intake m
Stage VI heads in bare form require a significant amount of work before they can be bolted
The small, 1.60-inch exhaust valve (shown here) is typical of most 915 or 516 castings. Wh
This 452 casting shows the open-style combustion chamber common to the '68-and-up big-bloc
Casting numbers can be found on the top of the intake runner, as well as the bottom side o
Edelbrock heads, unlike some other aftermarket units, oil the valvetrain through the origi
The Edelbrock Performer RPM heads are available with either 84cc or 88cc combustion chambe
Indy cylinder head offers several choices for the big-block Mopar enthusiast, including th
The 572-13 and 600-13 Indy heads have the rocker stands milled down and are machined to ac
If you want to see how the 572-13 heads perform on the strip, stay tuned. We just finished