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- Mopar Head Porting Templates Downloads
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- Mopar Small Block Head Porting Templates
#9---C.N.C. Super Prepped Heads | 6/27/2018 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
CNC SUPER PREPPED HEAD (updated6/7/12) Cylinder heads and their modifications are always a hot topic of conversation among gearheads, from rank amateurs to the top of the heap, professionals. Big ports, small ports, high velocity, reversion, C.F.M., F.P.M., etc. are all jargon that needs to be understood to enter into these high tech discussions, however, once into conversations you will likely find lots of disagreement on what is and what is not important. Any engine can benefit from some sort of air flow increase whether it’s a custom high flow valve & seat job on a Resto-Cruiser or a Hot Street car that includes a bowl porting. For the Hot Street and Street/Strip engine on a budget the question is what gives the most bang for the buck? Part of that answer will be how much bang do you want? The cost of ported heads directly relates to how much work is put into the heads along with how productive it is. The most bang for the buck comes from improving the low and mid-lift flow, for many reasons. First of all the price will be lower because of the time it takes to do the job. Any flow increases at low and mid-lift will benefit the total air flow available twice, once when the valve is opening and once more when the valve is closing. Whereas at maximum lift, the valve is only in that position for a short period of time reducing it’s contribution to the total flow. If the possibility exists that the heads may be completely C.N.C. or fully hand ported at a later time, what is done now, if done properly, should not have a negative effect on that later work. We will try to give you some ideas on what to expect from the porting that Hughes Engines calls their CNC SUPER PREPPED HEADS, for small blocks, when applied to the popular Edelbrock aluminum heads. The most important area of the port is the valve seat and the one half inch area before and after the seat. The actual seat, its angles and widths are the most critical areas and receive as much attention during research and development of the ports as the rest of the entire The exhaust seat is a different deal and incorporates some radii’s along with angles. The area below the seat is called the throat and transitions into the bowl. Each of these areas is customized into the seat and eventually into the runner. The area above the seat is blended into the chamber. This blending may include opening the chamber wall to unshroud the valve, especially around the intake valve. Blending may also include laying back the wall of the chamber directly across from the intake valve. All these are dependent on the port, seat, chamber, etc. In some heads these modifications are very productive; others it is a waste of time or can even hurt the air flow and power. Testing is the only way to know. The seat area and valve angles have the greatest effect on the air flow up to about .350” to.400”lift.. The port runner shape, size and finish have little effect up to that point. Above this lift point the port shape & size of the port starts to affect the flow. The seat area, although still effective, is not the major influence on the flow from about .400” lift on up. A major mistake among new or inexperienced engine builders is to look for the maximum air flow at peak lift. What you should be concerned with is the “area under the curve”. One of the things you will learn when porting cylinder heads is that you have trade-offs. You can concentrate on high lift flow at the expense mid-lift flow and vise-versa. You should make a choice that gives you the most area under the curve. This means more flow at each lift point. A port that flows 15CFM more at .600” lift is not nearly as good as one that flows 15 CFM more at .300” lift, especially if you only have .600” lift. In photo 1 we see a stock Edelbrock L.A. and Mopar Performance chamber and valve seats. The small block Edelbrock head flows up to 40 CFM more than the iron L.A. heads like the “X” and “J” that they replace. They have smaller combustion chambers and have a Photo 2 shows the chamber and seats after Hughes Engines newest C.N.C. Super Prep work. The intake seats are a multitude of proprietary angles and widths. The exhaust is based more on radii’s than angles on edges. The reason for the angles on the intake is for more fuel shear and better wet flow characteristics. With the Hughes seat the angle 45 ºactually sets a little proud from the other angles, Photo 3 -vs-photo 4.This helps the wet flow and can be cut when the heads are freshened without altering the seat width. The CNC machined chamber un-shrouds the intake valve increasing the air flow and encourages better wet flow in the chamber. Better wet flow increases power through better burning. Photos 5 &6 shows the before and after pictures of the port opening. The porting work at the gasket is Hughes’ deep port match and is part of the CNC Super Prep work. Chart # 2 shows the out-of-the box air flow on both the intake and exhaust ports. This chart show the air flow on the same flow bench after the seat & port work, and what the chamber work does for you. The flow figures shown are the average of 3 different ports. It is important to note that the heads were flowed on the same bench before and after so the gains are accurate and relative. Chart #2: These were new Edlebrock 60779 (LA) or Mopar P5153849 heads just out of the box. All numbers are checked & corrected @28”.
Notice how the stock intake flow levels off at about .500”. That pattern will continue throughout the other upgrades. To increase the flow above .500” will require the complete port to be opened up. Chart #3 is the same ports on Edlebrock 60779 (LA) or Mopar P5153849 with Hughes Engines CNC super prepped porting modifications.
We also do this same work on the Edelbrock 61779 (Magnum) heads.
On the Exhaust side, the gains are greater at higher lift because the port is considerably shorter. This flow improvement helps to reduce reversion. Reversion is the effect we see at the overlap point when the Intake valve is just opening and the Exhaust valve is just about to close. This is when the exhaust gas can flow up the Intake port, diluting the intake charge. The greater the overlap of both valves the greater the reversion. The art of building engines is filled with trade-offs and overlap is one of them. Let’s talk about the slight flow loss on the Intake from 500” lift. Cylinder head ports are passages with twists, turns and restrictions. As a restriction is removed the flow goes up, but there are still some restrictions left. As the restrictions that effect flow at lower lifts are eliminated, the flow volume increases to a point that pre-existing restrictions that were not problems, now become problems. This causes the flow at high lifts to stagnate somewhat. The ports can be fully C.N.C. ported and 2.08 valves installed which will remove most all of the restrictions and flow a lot more air “for a few more dollars”. So, O.K., how much power are the Hughes C.N.C. Super Prepped heads worth over out of the box heads? This depends on how the engine is built. On a 360 C.I. with a mild cam, good dual plane intake, headers and a true 10.5:1 compression ratio (Aluminum Heads must run more compression the iron heads), C.N.C. Super Prep work might be worth 20 – 30 more HP. On a Hot 408 C.I. or 416 C.I. stroker you might be looking at 30 – 50 more HP.And if you are really power hungry, Hughes can move the intake pushrod over .200” and supply off-set rockers, photo #9. The combustion chamber work will enlarge the chamber volume about 3-4 cc. Normally we will mill the head a few thousandths to return the volume to stock size. These CNC Super Prepped heads work well for hot street applications, all street/strip applications and in a budget oriented strip only application. Contact us for more information. (309) 745-9558 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
- Brand: Mopar Performance. Manufacturer's Part Number: P4120437. Part Type: Cylinder Head Porting Templates. Summit Racing Part Number: DCC-4120437. Quantity: Sold individually. In-Store Pickup: Choose In-store pick-up (OH, NV, GA, TX) on our web site.
- Mopar Porting Templates - RB / LA / Magnum heads Download the PDF here directly: (17 pages, 2.1MB) Mopar Porting Templates RBLAMagnum PDF-file Thanks to DaytonaTurbo and RapidRobert from the Moparts website.
- The 516s can be made to flow well with the right port work. A head porter on here has posted some impressive power gains with a low comp RV motor and 516 heads. Check out his thread. I would put in the 1.74 ex valves, and pocket port the area under the valve. Get some porting templates to help with port shape.
Selecting the best cylinder head for your application takes careful consideration and requires weighing many factors so you have the correct casting that matches your engine package. Heads flow air and manage the combustion of the fuel charge and, therefore, are critical for attaining the proper output level. You need to have your application and performance targets clearly defined so you end up with the correct head.
This Tech Tip is From the Full Book, HOW TO BUILD SUPERCHARGED & TURBOCHARGED SMALL-BLOCK FORDS. For a comprehensive guide on this entire subject you can visit this link:
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In the following sections, I cover most of the original production and the performance heads, but I focus on currently available heads. In the early 2000s, Chrysler/Mopar offered more than 30 different heads for the Mopar small-block engine, and this number does not include any actual current production heads. The aftermarket offers many more performance heads, which I also cover.
The head must work with all other engine components for the engine to be successful. The short block’s displacement, the compression ratio, the intake manifold, throttle body/ carb induction system, camshaft, and valvetrain all play important parts for the team that makes the final output of torque/power. If the short block is not up-to-snuff, the best heads can’t deliver the desired power. No air flows through the ports in the head unless the valves open (and the cam opens the valves), so the cam is a very important part of the airflow team, even though it doesn’t flow air.
Once you define your application and what you expect from the engine, you can select a set of heads to best suit this application. Prepping the heads properly and matching the rest of the engine parts to this head are the key factors to making high torque and power outputs.
Identification
Looking at the casting number is the most reliable method to identify a head. Typically this number is located on the top of the cylinder head but inside the valvecover gasket area, which means that you can’t observe it if the valvecover is installed.
So the first tip is that the A-engine uses a 5-bolt attaching pattern and the Magnum engines use a 10-bolt attaching pattern. The next tip is that A-engines use a 7-digit casting number and Magnum engines use an 8-digit casting number.
Some performance (non- production) and aftermarket heads are aluminum or cast iron and have unique casting numbers or other logos to identify them. Notice that the specifications are very similar among production-based heads, but the best spec is the intake valve head diameter, which is 1.92 for the Magnum and 1.75, 1.88, or 2.02 for various A-engines.
It is very easy to install large valves if the cylinder head is rebuilt, so using the actual valve’s head diameter to determine which version of a head that you have is flawed.
Production Cylinder Heads
Most production LA-engines are more than 40 years old, so the key is having one set of heads in good shape to use in a performance engine.
When building a max- performance small-block of 500 hp or more, one of the latest aftermarket cylinder heads produces much more performance than many of the cast-iron OEM heads. Cast-iron or aluminum Indy heads are an excellent choice. Although production heads can be ported and modified to accept modern valvetrains, you’re going to save time and money by starting with a current aluminum aftermarket model.
340
The 340 head provided exceptional performance and was highly desired and sought after for the A-engine. These heads are referred to as “915” heads because the last three digits of the casting number are 915. But they are also called “X” and “J” heads based on the cast letter on the head in addition to the casting number (versions of the 894 head).
These were good heads in 1968, but there are better castings in the production head lineup. The 308 head is regarded as the best A-engine casting, and it was in production from about 1988 through 1992, but it was not an exclusive casting.
Another aspect of these production heads is that the 1981–1987 318 4-barrel engines used 360 heads as part of the E48 high-performance 4-barrel or police option. After 1971, all high-performance production 340/360 heads had a 1.88 intake valve, which can easily be upgraded to a 2.02-inch intake valve for max-performance applications.
308/576
The 308 head is the best production cylinder head, and it uses a copy of the W2 exhaust port (perhaps the best-flowing exhaust port in any small-block head). It just flows more air. The roof of the intake is raised. With matching valve size, it makes more power.
Introduced in the late 1980s the 308 was one of three 360 castings that were installed on trucks from 1988 to 1992, so it is difficult to find in the typical junkyard. Mopar Performance began selling these 308 heads around 1990 as a service for Mopar Stock and Super Stock racers.
Although A-engine production stopped in 1992, dealers often were lucky to get them when ordering service heads. Then Mopar Performance sold the 308 castings machined as 360 production heads with 1.88-inch intake valves, and eventually a 340 version with 2.02 valves was offered.
Later, the casting number changed to “576” (the last three digits). It had the same ports as the 308 and they flowed the same; only the casting number changed. Both heads had the same open combustion chamber as the other 340/360 heads and the same 1.88/1.60 valve sizes. Mopar Performance created an offset pushrod version to duplicate the 340 T/A heads, but it wasn’t very popular. The 308/576 cast-iron head was quite popular for about 10 years when production stopped.
W Head
The “W” series of small-block heads are high-performance heads. The W2 was introduced in the early 1970s. It was probably the best cast-iron small-block head for 40 years. The W2 has a casting number of 3870810, and the large, oval intake ports easily identify it. The W2 was offered as an economy version with cast pedestals; the race version had offset rocker shaft stands.
The second-generation W2 was introduced in 1989–1990. The third-generation W2 was unveiled in 1998 and is visually different from the first two versions. Two large external ribs were added to each end of the head on the exhaust side and smaller ribs were added on each side of the short head bolts (exhaust side).
A closed-chamber version was added at this time, along with the capability to be used with the new 48-degree tappet blocks. This last version is a machining change and not a unique casting. By the early 2000s, Mopar Performance offered 10 different W2 heads.
Introduced in 1988, the W5 is an aluminum head that weighs about 25 pounds, but it is no longer available. The aluminum W7 was introduced a couple of years later. It had large ports and flowed a lot of air but was the last head designed before CNC-porting became readily available.
The aluminum W8 was introduced in 1998 and was only used in the NASCAR Craftsman Truck series and the NHRA Pro Stock Truck series. It weighs 35 pounds and was designed for CNC-porting. It also uses 15-degree valve angles rather than the standard 18 degrees. The W9 head was introduced in 1999. It weighs about 22 pounds, or 20 if it is ported. It was also designed for CNC-porting but some versions were designed for use without porting; it flowed 290 cfm out of the box.
Magnum
Released in 1992 on the 5.2L engine, Magnum heads use a “bathtub-shape” closed-style chamber rather than an open chamber. The Magnum chamber is smaller in volume than the A-engine chamber (60 versus 70 cc). It also uses a 1.92-inch intake valve and a 1.625-inch exhaust valve, which is larger than the production 360 but smaller than the 1968–1971 340. The stock Magnum’s intake port flows slightly better than the 360 A-engine’s intake port (190 versus 170 cfm), which may be due to the larger valve.
Another unique feature of Magnum heads is that there is no heat crossover in the center of the intake face. Because it is fuel injected, it does not need the heat in the intake manifold for driveability advantages. Magnum heads have 10 valvecover attaching screws and 8 rocker stands, one for each valve.
R/T
The cast-iron high-performance R/T head was designed for the Magnum engine as a direct replacement, and it’s essentially a Magnum engine W2 head. It flows more air than the standard head (229 versus 190 cfm) and has larger intake ports (180- versus 153-cc intake) using the same valve size. It has the “R/T” logo and the “Mopar” logo cast into the exhaust face between the short head bolts.
T/A
The 340 Trans-Am engine was produced with special cast-iron cylinder heads based on the “915” casting (3418915 casting number). The 915 was going to be the 360 production head in 1971 and the 1972–1973 340 head, and was specially machined for the T/A program.
The main differences were the use of the larger intake valve (2.02 inches), and the intake pushrod hole (machined) was moved away from the intake port. The actual as-cast ports were the same as the standard 915 heads. The moved pushrod required offset rocker arms (mechanical or adjustable) on all the intake valves.
Commando
The aluminum Commando head for A-engines was introduced in 2001. It was designed to be a “street” aluminum head, so it was interchangeable with the standard 340 heads. The intake ports were larger than stock cast-iron heads at 177 cc, and flowed better than stock cast-iron heads, at 222 cfm. These heads could be used with the standard stamped rocker arms. There was also a large-port, Super Commando aluminum-head version that required offset intake rockers.
Aluminum Magnum
Designed for “street” use, the aluminum Magnum head was introduced in 2000. It was interchangeable with stock cast-iron Magnum heads. The intake ports were larger than the stock cast-iron heads (at 177 cc) and they flowed more air (at 222 cfm). With any of the 360 and 1972– 1973 340 cast-iron heads, you should always upgrade the 1.88-inch intake valve to the 2.02-inch valve.
Head Spec Comparison
Many specifications relate to a cylinder head, and they can be used to compare one head to another. Many people focus on flow numbers, and most often the peak flow on the intake port, while exhaust is rarely considered.
A flow bench generates a curve of port flow according to valve lift, and the peak flow is at the peak valve lift. Valve lift is often disregarded, but it’s important. When comparing different heads, make sure the valve lift is the same and then look at the flow numbers so the comparison is valid.
For example, let’s assume that you are building a street/strip engine and have selected a .500-inch-lift cam. One head flow 280 cfm at .500-inch lift and another flow 300 cfm at .700-inch valve lift. The key is to look at the flow at .500 lift. The 300 cfm head may be 250 or 260 cfm at .500 lift, and there
fore the 280 cfm head becomes the better choice. Another thing that makes comparisons difficult is valve size. The 280-cfm head might have a 2.020-inch intake valve and the 300-cfm head might have a 2.100-inch.
Bigger ports are not always better and, in fact, ports need to be correctly sized to the engine package. Ports are usually sized by volume (in cubic centimeters). The typical 360 port is 166 cc and the ported W9 aluminum head was in the range of 260 to 270 cc. The W9 tends to be fl owed at high lifts, such as .700 to .800 inch, and the 360 is fl owed at lower lifts such as .500 to .600 inch. With differences such as these, the first measurement needs to be taken at your cam’s max valve lift. In our example, it’s .500 inch. If that is close, determine flow at half lift, which is .250 inch in the example. Usually the flow curve shows the flow at .200 and .300 inch, so pick one and check the flow at that point.
The higher fl ow at the .200/.300-inch point is the better head for your application if they were tied at .500 lift. The valve and the valve job also affect the airflow capability. It’s also important where the valve sits in the chamber (don’t sink the valve) and how the air enters the chamber at low lifts (chamber reliefs). The valve job angle and the shape of the underside of the valve head are also important to the airflow numbers.
Aluminum Heads
Most aluminum heads use larger port volumes than the similar cast-iron heads. During the cast-iron head drought, the aluminum heads were the only choice. Aluminum castings lend themselves to low-volume production, so these may be made in batch runs of 100, 500, and 1,000. This makes them popular with the aftermarket for racing applications, which spills over into many other performance uses.
The aftermarket built the first aluminum cylinder heads for the Mopar A and Magnum small-blocks. Chrysler made the only cast-iron service heads for the A-engine small-blocks and they were kept in stock for 10 years or so. Mopar Performance had provided heads for most engines.
Between 2000 and 2010, all this changed and most Mopar heads were no longer available. In the past couple of years, this has changed again; there are now several versions of aluminum heads.
The three aluminum heads from Edelbrock, Indy Heads, and B1-BA all flow about 260 cfm in stock configuration. That means that economics should decide your selection. These heads are also offered in ported form where the Indy Heads version (339) and the Brodix B1-BA version (340) are equal, so economics can again be used to select between these two heads. The latest data indictes that the newest B1-BA CNC-ported head by Koffel’s Place makes more than 360 cfm, which makes it the best-ported small-block head to date!
Edelbrock Aluminum Heads
Edelbrock offers several aluminum heads for A-engines (five valvecover screws). The 1968–1971 340 “A” head features a larger, open combustion chamber. It provides clearance for the piston because it sits above the deck at TDC. With all other A-engines (including 318s, 1972–1973 340, and all 360s), the pistons sit below the top of the block, so this special feature is not required.
The aluminum A-engine head has chamber volumes of 63 and 65 cc, intake port volume of 171 cc, and valve diameters of 2.02-inch intake and 1.60-inch exhaust. These dimensions are the same as for the 1968– 1971 340.
Edelbrock carries aluminum heads for Magnum engines. These heads have chamber volumes of 58 cc, intake port volume of 176 cc, and valve diameters of 2.02-inch intake and 1.60-inch exhaust. Although these dimensions are the same as the 1968–1971 340, the heads are different from the production Magnum. Edelbrock also offers aluminum heads for use with hydraulic cams and hydraulic roller cams. Similar to the A-engine, heavier valvesprings are used for a hydraulic roller that has higher-load springs. These heads also use 11/32-inch valvestem diameters and manganese-bronze valveguides. They use 14-mm x 3/4-inch–reach spark plugs (recommended Champion RC12YC or equivalent). The valvespring installed height is 1.800 inches.
ARP lists the same head bolts for the Edelbrock Magnum heads as for the production version, which means five extra-long head bolts. Caution: The specs indicate that these heads use 3/8-inch rocker studs, which may mean that you need larger bolts or must change the valve gear. Both Edelbrock aluminum heads (A-Engine and Magnum) flow the same 260-cfm intake at .600-inch lift and 251 cfm at .500-inch lift. Both are very good numbers. Edelbrock aluminum heads flow excellent out-of-the-box, and lead the affordability list at most shops. It is a great bolt-on head. At this time, Edelbrock does not list ported upgrades.
Caution: ARP lists the same head bolts for Edelbrock heads as for the W2, which means two extra-long head bolts (a typical 340 or 360 has five long and no extra-long). Edelbrock also has an aluminum head for race only, which features a 58-cc chamber and a larger 225-cc intake port. The ports are fully CNC-ported and use 16-degree valve angles. Flow numbers were not published.
Aluminum Indy Heads
The Indy Heads 360-1 and 360-2 are two versions of the company’s aluminum Mopar small-block heads. The 360-1 is the rectangular-port version and the 360-2 is the oval-port version (similar to the W2). The 360-1 has a 210-cc intake port, 2.100-inch intake and 1.65-inch exhaust valves, and a 63-cc heart-shape combustion chamber. It also uses .800-inch offset intake rockers.
Many options are offered, such as rocker shafts or Jesel rockers, 10-bolt or 18-bolt head bolt patterns, and several porting options. The stock intake port flows 280 cfm at .700 inch; bowl-port and intake match yields 290 cfm. Super-modified porting yields 309 cfm, and the full porting and polish yields 339 cfm, both at .700-inch lift.
The 360-2 oval-port Indy aluminum head uses a 180-cc intake port and flows 252 cfm at .700-inch lift. The chamber is 63 cc, the intake valve is 2.100 inches, and the exhaust valve is 1.65 inches. In its full CNC-ported configuration, the port size increases to 230 cc and the flow goes up to 322 cfm at .700-inch lift.
B1-BA Aluminum Heads
Koffel’s Place designs and Brodix casts the B1-BA Mopar small-block aluminum head. It features 18-degree valves with 2.08-inch intake and 1.60-inch exhaust valves. The exhaust pattern accepts standard headers. Production A-engine intake manifolds and stock, five-bolt valvecovers can both be used. The stock intake port is about 195 cc and the stock combustion chamber is 65 cc. The standard setup uses shaft-mounted rockers.
Many options are offered, including CNC-porting. Recent CNC-ported intake ports have flowed more than 370 cfm.
Cast-Iron Heads
All the cast-iron heads pretty much disappeared in the early 2000s. Cast iron is difficult to pour in limited quantities, and many cast iron foundries have gone out of business. So until about 2014, cast-iron heads were not easy to find. Indy Heads introduced a cast-iron version of its aluminum head and produced it in an A-engine version (with rocker shafts) and in a Magnum version (8 rocker pedestals). Both are machined from the same casting.
Cast-Iron Indy Heads
Indy Heads offers cast-iron 360 LA-X heads for the A-engine, which feature five valvecover bolts and the dual-exhaust bolt pattern. The cast-iron A-engine head has chamber volumes of 62 cc, intake port volume of 179 cc, and valve diameters of 1.92-inch intake and 1.625-inch exhaust (with 2.02- and 2.055-inch options).
The company also offers heads for use with .525-inch lift (hydraulic cams) and .600-inch lift (mechanical cams). The .525-lift version is for hydraulic cams but can be used with low-lift mechanical cams if desired; there just aren’t many mechanical cams that lift only .525 inch. The .600-inch-lift version, a mechanical cam, is most often used because very few hydraulic cams have lifts in the .525- to .600-inch range. The valvespring is the change and valve lift is the key. These heads also use 5/16-inch valvestem diameters and stainless valves.
Caution: These heads use five extra-long head bolts similar to the Magnum, plus they may not use standard 340/360 spark plugs. Indy Heads also makes a cast-iron head for Magnum engines called the 360 MA-X. Its specifications are similar to the above A-engine head with valve size and spring options. The Indy Heads cast-iron head is the best available today. Both A-engine and Magnum versions are available. Both of these iron heads feature a 62-cc chamber.
Bare Heads
Several aftermarket manufacturers offer bare (rough) heads. Chrysler referred to these as partially machined heads; Edelbrock called them raw or semi-finished. Essentially, the head has been machined with the exception of the valveseats, combustion chamber, and ports, which are as-cast. In most cases, the valveguide hole is machined, but guides may or may not be installed. These heads provide engine builders the latitude to machine the heads to specific requirements, and therefore can be CNC-ported. Most manufacturers offer this option, but only Edelbrock puts details in its catalog and on its website.
Cylinder Head Selection and Prep
When selecting the head for your build, focus on three features: material (cast iron or aluminum), valve size (intake and exhaust), and peak intake flow. Although there’s more to a cylinder head than these specifications, they are very important. With so many head models, designs, port sizes, and combustion chamber shapes available, you need to select the head for your build very carefully. There should be no reason to hunt through junkyards and hope you find the specific head for your performance use.
Several considerations must be addressed first, such as aluminum versus cast iron and repair versus new versus used. Cast-iron (Indy) and aluminum heads (Edelbrock, B1-BA, Indy) are available today that do a good job for the Mopar/Chrysler small-block. Originally, cast-iron heads were less expensive but today cost close to the same as aluminum heads. Aluminum heads offered more flow, but that may not be the case today, short of the W9 head and CNC-ported heads in general.
Overall, I do not recommend going the used route, but there are exceptions. So the choice comes down to buying new or doing repairs. The Indy Heads, Edelbrock, and B1-BA/Brodix are excellent choices for max-performance street use. The best small-block head is the W9, either as-cast or ported. Availability is the factor. The W8 head was a good head but is no longer available. To recommend it, the head must be cost-effective and readily available, so the Edelbrock aluminum head is my first choice.
Cost is the deciding factor between the Indy head and the B1-BA. Brodix provides more technical information on the B1-BA in its catalog and the company offers both the standard 18-degree valve angles and the 15-degree angle that were common in the W8 and W9 heads.
All three manufacturers offer CNC-ported versions and there seems to be more information on the Brodix and Indy Heads versions. Based on fl ow numbers, the CNC-ported Indy head makes 339 cfm with a 2.100-inch intake valve, and the CNC-ported Brodix B1-BA makes 347 cfm with a 2.14-inch intake valve. Brodix shows the stock or as-cast B1-BA fl owing 269 cfm, which is also very good. CNC-porting makes more horsepower but a full porting job is probably not needed for the street/ strip application.
Remember that other specifications must be kept in mind too. They include: compatibility, port volume, bolt patterns, and combustion chamber type.
Compatibility All parts of an engine must function as a complementary system. One cylinder head is not best for all applications. So you need to carefully select the proper specifications for your goals and build. The valves must work with the port, as finished, and the port-valve combination must work with the cam selected. You do not want to use a .700-inch lift port with a .500-inch lift cam, or a .500-inch lift port with a .700-inch lift cam, which are common pitfalls to avoid.
However, the exhaust and intake manifolds, throttle body/carburetor, and cubic inches all play into the same equation. For example, in NHRA Stock and Super Stock classes, which allow only limited modifications, the 340 and 360 engines (using the same head and induction system) do not work well with the same cam, converter, gear, etc. Simply put, the 340 sets up like a short-stroke engine and the 360 sets up like a long-stroke engine.
For an interesting comparison of how heads and cams, valve lift, and compression ratio work together to change the engine’s operating band (engine RPM), torque, and horsepower outputs based on horsepower per cubic inch, you can review Edelbrock’s five basic packages. They include upgrades from 250 to 325, to 400, to 470, to 610, and to 720 hp based on Edelbrock heads and hardware. Information is available on the company’s website under “Power Packages.”
Port Volume
Many aspects of a cylinder head affect actual port volume. Although valve size stays the same, a slight tweak (grind) on the valveseat sinks the valve slightly and changes the port volume. Changing the valve from a tulip valve to a nailhead valve changes the port volume.
Milling the intake manifold face to make the intake manifold fit after milling the deck surface changes the port volume as well. Any porting that is performed also changes the port volume. That is why port volume is not used as a control specification but as a general guideline.
Intake and Exhaust Bolt Patterns
The Mopar A-engine intake bolt pattern is perpendicular to the manifold face; the Magnum pattern of the attaching bolts is vertical. The 1964–1965 273 heads also used vertical intake attaching screws. Also, the W-series heads, such as the W2, used a wider-spaced attaching bolt pattern for the bolts on either side of the actual intake ports.
Mopar Head Porting Templates Downloads
The end bolts stay in the same location because the bigger intake ports are best for the higher-flowing ports in performance applications. End bolts stay in the same location (only the ones next to the ports move away from the ports) to gain wrench clearance for the ones on the inside of the turn. The intake manifold must match the cylinder head ports, so the larger runners crowd the inside-turn manifold bolts (the two closest to the center of the engine) to the extent that you cannot put a wrench on the bolt head. Widening the spacing solves this problem very easily.
The A-engine and the Magnum use the same exhaust bolt pattern. The original W2 cast-iron head spreads the exhaust bolt attaching pattern away from the ports. In the second generation of W2 heads, either the standard pattern or the wider W2 pattern was machined into the head. You should plug the holes in the dual-exhaust pattern that are not used to attach the exhaust manifold/header; use small Allen screws and seal the threads. Indy uses this dual-pattern approach. The the Magnum exhaust side uses spark plug shields inserted into the head.
Combustion Chamber Type
Many aftermarket performance heads use a machined chamber, so it is easy to revise. The typical A-engine head uses an open chamber; the Magnum engine uses a closed (bathub) chamber.
The third-generation W2 offered a closed-chamber head as an option with volumes in the 47- to 55-cc range (standard open-chamber volume was 70 cc).
Many aftermarket heads use a heart-shaped chamber. Most chambers are really a modified heart shape, which is pretty close to the bathtub shape. Relieving the chamber around the valves for increasing the port’s airflow enlarges the chamber slightly and tends to make the heart into more of a bathtub shape.
High-Performance Valve Job
The two parts of a valve job are half to the valve and half to the cylinder head. Aluminum heads use a valveseat insert into the head; cast-iron heads typically grind the valveseat directly into the casting, but seat inserts can be used for repair purposes. One of the secrets to a valve job with any valve insert is to create a smooth transition from the port to the valve job and into the chamber. This is one of the advantages of CNC-porting, if the CNC machine does the port and the valveseat.
Valve Centers
Mopar Head Porting Template
Almost all A-engine and Magnum heads use the same 1.87-inch size for valve centers. The W9 uses 1.936-inch valve centers for large valves. Aftermarket heads can be modified to add a 1.936-inch valve, but most are built with a 1.87-inch valve.
Air Pump Holes
Most newer A-engine production heads have emission air pump holes in the exhaust flange just below the exhaust port on each cylinder. If the heads are going to be used for racing or other performance purposes, plug the threaded hole with an Allen screw. If the air pump holes are left open, they leak exhaust gas when headers are installed.
These holes are not machined on the 360 high-performance (E58 option) or the 340 cast-iron heads.
Rocker Stands
Rocker stands fit between the rocker shaft and the cylinder head; basically, they replace the cast-iron rocker pedestal. To use rocker stands the machine shop machines off the pedestals. The most common use of rocker stands was for race W2 heads. The rocker stands allowed the rocker shaft to be raised, which allowed a longer valve and taller valvesprings, and offset away from the valves, which allowed the rocker arms to be stronger (no increased relief on the underside). The econo-W2 head used as-cast pedestals.
Special Head Considerations
Many cylinder head and overlap features are important to the engine’s operation and performance. Compression ratio and airflow are key players in the performance equation and are affected by the cylinder head.
Compression Ratio Measurement
The first step in measuring your engine’s compression ratio is to cc the combustion chamber in the cylinder head. Initially, you only need to measure one chamber. I recommend one of the two center chambers. To cc the combustion chamber in the head, you need the following: a 100-cc burette; a flat, clear, 1/4-inch thick Plexiglas plate; a cc-ing fluid, such as parts cleaning solvent or rubbing alcohol with food coloring added; and a light grease such as petroleum jelly.
Compression Ratio Calculation
The formula for calculating the engine’s compression ratio is detailed in Chapter 3. Basically, it is the VBDC divided by the VTDC. The biggest part of the VTDC is the chamber volume, which must be cc’d. You want to know your basic compression ratio as soon as possible so you can order pistons, mill decks, mill piston tops or to have the compression ratio where you want it for your application and fuel use. If you are shooting for a compression of 9:1 and you find that it is 10:1, you must lower the ratio by one point. If you are building the engine, a new set of pistons is the best solution. If it is already built, try a thick-head gasket or shim. If the ratio is 8.5:1, you could probably mill the block and heads to gain the 1/2-point of ratio. However, if it is 8:1, new pistons are best because it would require too much milling, which causes other problems.
Displacement Calculation The first part of the compression ratio equation, or VBDC, is basically the displacement of one cylinder plus the VTDC. This makes it important to calculate your exact cylinder displacement. For example, if your engine has a 3.94-inch bore and a 4.00-inch stroke, the displacement is 390.15 ci (8 x .7854 x 3.94 x 3.94 x 4.00).
For use in your compression ratio calculation, you only want one cylinder’s displacement (sometimes called swept volume), so you divide the displacement by the number of cylinders. In this case, it’s 48.77 ci (390.15 ÷ 8).
To use the number in the compression ratio formula, you need to convert this volume to cubic centimeters, which is 799.17 (48.77 x 16.387).
Shrouding The combustion chamber allows the valves to open into an area on one side, next to a valve. For about 90 degrees, where the valve is next to the chamber wall, the valve is shrouded as it lifts off the valveseat. On production cast-iron heads, a valveseat cutter generally relieves this area for each valve. Enlarging this basic relief helps airflow. How
ever, you must not get carried away because the seal ring on the head gasket must seal to the head surface in this area so any increased relief must stay inside of the gasket’s seal ring. This is commonly performed on aluminum heads, especially the ones that are CNC’d.
Valves
A-engine and Magnum engine valves open on-center. Simply put, this orientation means that the head diameter runs across the widest part of the bore. As a result, big-valve 340 heads can be used on small-bore 318 blocks. It also means that if the valves are the same size, such as 2.02 or 1.60 inches, the valves are less shrouded as they approach max lift.
Magnum engines and A-engines do not use the same valves. Because the diameters are slightly different, the Magnum uses a slightly shorter valve by about .060 inch. It also uses a thinner valvestem. They are not interchangeable.
Length
The Magnum intake valve has a length of 4.91 inches and the exhaust length is 4.92 inches. A-engine intake valves are 4.98 inches long and the exhaust valve lengths are 4.97 inches.
Race versions of the W2 and W5 A-engine heads use .300-inch-longer valves, 5.28-inch intake and 5.29-inch exhaust. This increases the valvespring installed height from 1.70 to 2.00 inches. More installed height allows the use of bigger springs, which allows more valve lift, which works with the big ports that flow more air at high lifts. Some aftermarket heads use longer valves with the increased installed height/max valve lift.
Stem Diameter
A-engines, both the 273/318 group and the 340/360 group, use 3/8-inch valvestems. All Magnums use 8-mm valvestems, which is very close to 5/16 inch. In the aftermarket, 11/32-inch valvestems are popular. Some aftermarket heads use 11/32 x 5/16 stems.
Head Diameter
The 340 valves’ head diameters are the most popular at 2.02 and 1.60 inches for the A-engine. The 1.88-inch intake (360) is also popular. Oversize valves, such as 1.65-inch exhaust and 2.08-inch intake, are also common. If a 2.15-inch intake valve is to be used, wide valve centers must be used. The Magnum uses a 1.92-inch intake valve and a 1.625-inch exhaust valve, with oversize intakes of 1.97 and 2.02 inches also available.
Material
Both intake and exhaust valves are made from steel. In general, the intake and exhaust are not made from the same steel alloy. The exhaust valve sees more heat so it uses a special alloy. Most aftermarket performance valves are made of stainless steel. Stainless steel is also harder and stronger than standard valve material and this hardness helps the engine if unleaded gas is used. Stainless offers an option to hardened valveseats.
For max-performance applications, the aftermarket offers titanium valves, which are considered race-only parts. They are lighter than stainless valves and are also strong, but they are quite expensive. As valve heads become larger and valves become longer, they are heavier. Titanium is one way of making the valve lighter without giving up diameter or length.
Best Mopar Heads
Valve Seals High-performance valve seals are made of high-temperature Viton. The standard A-engine valve seal has an umbrella seal that slips over the valvestem; the Magnum valve has cup-style seals that fit over the valveguide and must have the guide sized to accept it. Seals must be inserted inside the valvespring. The umbrella seals fit inside of the single spring; the dual spring does not. High-lift cams use dual springs.
One option is to use a PC seal in place of the umbrella seal. The PC seal fits over the guide and requires the top of the guide to be machined to accept it. Also, this seal requires .100-inch clearance, so you lose the thickness of the seal off the valve lift. If you plan on running on the street, you want to use a production seal (umbrella or Magnum-style), which means using a single spring with dampener (optional). There are good single springs that allow .500-inch valve lift, up to .535-inch valve lift.
Head Gaskets
Today most of A-engine and Magnum head gaskets are about .040-inch thick. Most use MLS construction.
Four- and Six-Bolts
The production small-block gasket uses four bolts around each chamber (10 bolts per head). For very high compression ratios and racing applications, Mopar/Chrysler introduced blocks and heads that featured six bolts around each chamber (18 bolts per head). Cometic, Fel-Pro, and others offer special six-bolt head gaskets for this application. The W8 and W9 heads were designed for the six-bolt pattern.
The six-bolt pattern is designed so that if you have a six-bolt head or block but do not want to use this feature, you can use a standard four-bolt gasket. For example, if you have an R3 bolt with the six bolts machined, but you have an Indy four-bolt head, you can use the four-bolt gasket and leave the extra bolt holes empty.
Street Supercharger
Several aftermarket companies offer street supercharger kits for Magnum engines, and most kits are set up for the Dakota, Ram trucks, or Jeeps because the engine compartments are large. Magnum engines in these vehicles were built with a compression ratio over 9:1, but a supercharged engine on pump gas (92 octane) should have an 8:1 compression ratio. If the ratio isn’t changed, the engine detonates and breaks parts, blows head gaskets, scuffs pistons, etc.
Changing the pistons to reduce the ratio one full point is expensive and time-consuming. Cometic offers an MLS gasket that is .120-inch thick, which drops the engine’s compression ratio about one full point and solves the problem.
Copper Head Gasket
Copper head gaskets are suitable for supercharged race engines because they support high compression. Typically they are used with O-rings. They come in thicknesses of .042, .051, .062, and .081 inch. Manufacturers also offer special bore sizes. If the copper gasket is not damaged, it can be re-used.
Mopar Small Block Head Porting Templates
Written by Larry Shepard and Posted with Permission of CarTechBooks
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