Due to their ability to regulate the input and output of airflow into the cylinder heads, 862 heads are optimal for compression.
If you need a complex cylinder head with enough power to boost your vehicle’s performance and efficiency, go for the 862 cylinder head.
General Motors produced 862 engines with a GEN-III Cylinder head with an aluminum build-up; they are also sand-cast, making them able to yield higher compression than other cylinder heads; for example, the 799 heads.
862 also comes equipped with a greater heat release rate and faster engine ignition because of the cylinder compression; it also features a high internal combustion ratio, to mention a few.
What are 862 Heads?
862 heads refer to a type of cylinder heads that are sand-cast and have cathedral port intake runners with a volume of 200 cc. They have the same port and valve sizes as 706 heads, which are also stock LS heads.
The only difference is that 862 heads are made of a stronger material than 706 heads, which are semi-permanent mold cast.
The 862 casting number does not identify these as the fourth generation “LSX” style head with a high-flow, rectangular port design.
That is a misconception that is often repeated online. The fourth generation “LSX” style head has a casting number of 823, not 862. The 862 heads have a cathedral port design, which is the same as the third generation “LS1” style head.
Some key features and specs on 862 cylinder heads are:
- 200cc intake port volume
- 61cc combustion chamber size
- 1.89″/1.55″ intake/exhaust valves
- Compatible with LS1, LS2, LS3, LS6, and LS7 style intake manifolds
- Works with standard LS valvetrain
- Designed for rebuildable high-performance applications
The intake ports on 862 heads flow slightly less than the stock 243 heads that come on most 5.3L LM7 engines from the factory.
However, the 862 heads have a smaller chamber size, which raises the static compression ratio by approximately 0.5 point on otherwise stock 5.3L engines. This can improve the power output and durability of the engine.
LS engines equipped with a set of 862 LS heads may see some gains in horsepower and torque across the entire RPM range compared to stock heads.
However, the gains are not as significant as some other cylinder heads that offer better airflow and velocity, such as 243, 799, or 317 heads.
Upgraded valve springs are not required on the 862 heads in order to handle higher RPM operation and increased valve lift.
They work with all the stock LS valvetrain components. However, some machining or modification may be needed to fit them on some LS engines, especially those with larger bore sizes or higher compression ratios.
| Material | Aluminum |
| Manufacturer Part Number | 12559863 |
| Intake Port Shape | Cathedral |
| Exhaust Port Shape | D – Port |
| Intake Port Volume | 200 cc |
| Exhaust Port Volume | 70 cc |
| Combustion Chamber Volume | 61.15 cc |
| Intake Valve Diameter | 1.89 in. |
| Exhaust Valve Diameter | 1.55 in. |
| Compression Ratio | 9.5:1 |
| Price | $290.95 |
| Compatibility | LR4, LM4, and LM7 engines. |
What Makes 862 Cylinder Heads Unique?
General Motors, one of the biggest car-making companies globally, designed and currently manufactures all 862 cylinder heads.
A unique aspect of General Motors’ initial design can be found in the sand-casting manufacturing process. The process enables the 862 heads to provide additional air compression compared to similar competing products.
The 862 heads’ compression ratio is known to be higher and more advanced than any similar product currently available on the market.
The improved compression ratio allows the 862 cylinders to withstand more engine pressure and heat, demonstrated by the incredibly high heat dissipation rate and ignition speed.
A car’s combustion process largely relies on its specific cylinder heads’ performance. If the performance is high, which is the case for 862 heads, the car’s combustion process will operate with added efficiency and smoothness.
Initially, General Motors designed the 862-cylinder heads to seamlessly integrate with LM4, LR4, and LM7 engines.
In addition, the 862 heads should be placed above the engine block, with the design effectively covering the cylinders while simultaneously creating an energy-generating combustion chamber.
The main advantage of the 862 cylinder heads is demonstrated by their ability to remain tightly sealed while having enough space to direct air and fuel directly into the cylinders’ chamber.
Symptoms of Cracked 862 Heads
The symptoms you can experience when 862 heads crack are quite variable. It’s essential to recognize them as quickly as possible to avoid engine damage and having the vehicle break down.
There are four primary symptoms that you’ll notice when the cylinder heads crack during vehicle operation.
- You experience an immediate drop in oil levels.
- The coolant levels get lower without evidence of a leak or its temperature changes.
- The engine performance starts suffering.
- You begin to see smoke coming out of the vehicle’s exhaust.
The most common reason for a cracked cylinder head involves the vehicle overheating. When this issue occurs, you might have the coolant flow restricted or experience head gasket failure.
In extreme instances, a damaged or cracked cylinder head can result in the engine failing to operate permanently.
Most garages and mechanics can recondition and repair a cylinder head for a reasonable price. It depends on the value of the part and how much labor is needed to complete the work.
Common Faults with 862 Heads
The common fault 862 cylinder heads users encounter is that cracking is bound to occur on the cylinder with frequent use, which gives room for oil and fluid leakage, which can cause severe damage if not noticed on time.
Aside from the cracks, which can be resolved by replacing the damaged cylinder head, there’s no other problem.
Although a replacement could cost around $750 to $2000 if you’re purchasing from an auto dealer, it would cost less if you get it directly from General Motors.
Are 862 Heads Any Good?
The aluminum 862 heads are a lightweight choice for engine design. This attribute contributes to improved fuel economy ratings while dissipating heat more efficiently.
They’re typically found in high-performance designs, such as race cars, while providing the other features of this casting.
General Motors is responsible for manufacturing the 862 cylinder heads. They’re a sand-cast product designed to provide more compression than similar products. That gives this option an advantage, especially when compared to 799s.
Since the 862s come with a compression ratio that leads to an increase of in-cylinder pressure, you receive a faster ignition and higher rate of heat discharge with the updated design.
That helps the combustion process run with extra smoothness and efficiency.
Are 862 or 706 heads better?
If you’re contemplating 862 heads Vs. 706, the 862, and the 706 heads are awesome vehicle cylinder heads. However, the 706 heads are more sophisticated than the 862 heads.
The 706 heads are superior to the 862 heads because they are semi-permanent mold (SPM) made. Meanwhile, the 862 heads are relatively sand cast.
The semi-permanent mold (SPM) method is more consistent, even after a porting job. On the other hand, the sand cast cylinder heads (862) may not be consistent after porting the cylinder head.
If you desire a more sophisticated cylinder head for your vehicle’s engine, 706 is an incredible choice compared to 862 heads.
Technical Details on 862 LS Heads
Now that we’ve covered the basic idea of the 862 heads, let’s look closer at some of the technical details and design features that make them perform well.
#1. Cylinder Head Design.
The 862 heads are cast from A356 aluminum alloy rather than iron. This makes them lighter and more resistant to heat than the stock cast iron heads.
The castings are CNC machined to smooth out the ports and chambers to under 63 Ra. This improved surface finish reduces turbulence and friction as air flows through the ports.
High performance multi-angle valve jobs are precision cut onto the seats. The bowls are hand blended to optimize flow and swirl. Stainless steel 1.89″ intake and 1.55″ exhaust valves are used to handle high RPM operation.
The valve seats and guides as well as the entire combustion chambers are CNC profiled. This significantly improves airflow and mixing compared to the stock cast iron heads.
#2. Intake Port Design.
The LS intake ports on the 862 cylinder heads have a cathedral port shape, which is the same as the third generation “LS1” style head. The port shape and volumes are optimized to produce good low and mid-lift flow while maintaining high velocity.
At .600″ lift the intake ports flow around 240 cfm at 28 inches of water. The intake ports have 200cc of volume, which is the same as the stock 243 heads.
The intake flange on the 862 LS heads accepts stock LS1/LS2/LS6 manifold bolt patterns. So these heads work with standard LS intake manifolds making them easy to swap.
#3. Exhaust Ports And Headers.
The D-shaped exhaust ports on the 862 heads flow around 200 cfm at .600″ lift. This is slightly better than stock castings but still able to maintain good velocity for low and mid-range power.
The exhaust ports come CNC profiled and hand blended from the factory. With some mild porting they can flow well over 220 cfm.
Fitting headers is straightforward thanks to the stock LS exhaust manifold bolt pattern on the 862 castings. Popular brands like Hooker, Kooks, and others offer compatible LS swap headers to take advantage of the high flow exhaust ports.
#4. Chamber And Compression Design.
The 862 heads have a smaller combustion chamber size than the stock 243 heads. The chambers measure 61cc, which bumps static compression over 10:1 with a standard 3.622″ LS crankshaft. This can improve the power output and durability of the engine.
The compact, heart-shaped chambers on the 862 cylinder heads feature a quench pad to improve detonation resistance. The sides of the chamber are CNC machined to reduce hot spots and improve flow.
Pros And Cons Of 862 Heads
Here are the pros and cons of the 862 heads:
Pros
- Made with durable aluminum
- Lightweight cylinder heads
- Cost-effective option
- Excellent combustion chamber volume increases the compression ratio
Cons
- Smaller intake and exhaust port volume
- Smaller intake and exhaust valve diameter
- Not suitable for high-performing vehicles
Installing 862 LS Cylinder Heads
Now that we’ve covered the benefits and top engines for the 862 heads, let’s go over what’s involved to install them on your LS build.
Remanufactured Vs New Heads
You can source 862 heads brand new or opt for quality remans. New castings are great but more expensive. Remanufactured heads offer excellent value.
When remanufacturing 862 heads, machining equipment like Serdi valve seat cutting tools and Sunnen servo-driven cylinder hones are used to guarantee OE-level precision.
Fully remanufactured heads come with CNC ported bowls/chambers, milled decks, three-angle valve jobs, and updated valve seals. This process ensures reliable performance and longevity.
Parts Needed For Install
Along with the heads themselves, here are the key components required to complete the 862 head swap:
- Valve springs – dual springs with titanium retainers rated for .650” lift
- Head gaskets – multi-layer steel MLS gaskets
- Head bolts – torque to yield GM head bolts highly recommended
- Pushrods – adjustable pushrods if changing rocker geometry
- Rocker arms – 1.7 ratio recommended for street use
- Lifters – check for binding and upgrade if needed
Surface Prep And Installation
Once you have all the parts, here are the steps for installing 862 heads:
- Clean and inspect the block deck and 862 head bottoms for flaws
- Surface the decks and torque plates to ensure proper sealing
- Test fit the heads and check for binding, adjust as needed
- Lube head bolts and install with a torque wrench to GM specs
- Degree in the cams, verify valve timing events line up
- Install valves, keepers, seals, springs, retainers, pushrods
- Adjust rockers, check pushrod length is correct
- Install valve covers, prime oil system, verify proper flow
With the heads torqued down and valves adjusted, the 862 heads are all set! Then you can break-in the new valvetrain.
Where to Buy 862 LS Cylinder Heads?
Now that you’re familiar with the 862 heads and how to install them, here’s a quick guide on sourcing them for your LS project.
OEM GM Castings
You can still find brand new OEM 862 cylinder heads from some dealers and parts warehouses. However, GM discontinued production so inventory is very limited. Expect to pay over $2500 per pair.
Top Remanufacturers
Most builders rely on remanufactured heads which offer comparable quality for less cost. Some reputable 862 reman sources include:
- Texas Speed – Fully remanufactured castings with multiple finish options to choose from
- Summit Racing – Large selection of affordable 862 castings guaranteed to meet OE specs
- Blue Print Engines – Great quality reman LS heads including 862s ready for drop-in install
Core Deposit
When buying remans, expect to pay a core charge up front that is refunded once you send your old heads back. This is typically around $500.
Remanufactured 862 heads run $1200-1800 for assembled castings. So with the core charge, plan around $1700-2300 total for a remanded set.
Used LS Heads
You can save money buying used 862 castings from forums, Facebook groups, Craigslist, etc. But inspect carefully to ensure the head decks, seats, guides, and valves are in good shape.
FAQs.
Q: What are the good LS heads?
LS6 was specifically designed by General Motors (GM) as the best performance. It was designed to surpass the old LS1. The LS6 did an incredible job that even the “243” casting was later recycled on LS2.
Although GM does not produce the LS2 and LS6 anymore, you can still get brand-new sophisticated bare castings for $850 from any Chevrolet high-performance parts dealers on the automotive parts market.
Q: What heads came on 4.8 LS?
The LR4 cylinder heads came on the 4.8 LS iron block engines of GM trucks. They were introduced around 1999 besides the LQ4 and LM7 truck engines which were the first set of LS engines for GM trucks.
The incredible LR4 heads were available in various GM vans, SUVs, and pickups from their inception until around 2007.
Meanwhile, if you were contemplating the period within which the LS1 or LS6 engines were introduced, the LS1 was a predecessor to LS6, and they were introduced in 1997. On the other hand, the LS6 was introduced in 2001.
Q: What heads are on LM7?
The 862 heads are on the GM’s LM7 engines. The cylinder heads are designed with aluminum materials with a 61cc combustion chamber volume. They also come with a cathedral-shaped intake port and an oval exhaust port.
The 826 cylinder heads on LM7 have an intake runner volume of 200cc, exhaust runner volume of 70cc, 1.890 in. intake valve diameter, and 1.550 in. exhaust valve diameter. The cylinder heads also have a Torque to Yield (TTY) bolt style.
Q: Are 5.3 and 6.0 heads the same?
The 5.3L engines are not the same as 6.0; hence, if you use the same cylinder heads with a cathedral-shaped intake port on both 6.0 and 5.3L engines, you will lose compression in the case of your 5.3L engine.
The loss of compression is due to the larger chamber on the cylinder heads of a 6.0L engine. 5.3L engines are completely different from 6.0L engines. 5.3L engines are 3rd generation aluminum block engines, and they have a truck manifold.
Meanwhile, 6.0L engines are 3rd generation iron block engines, and they also have an intake manifold of a truck. Another sign that distinguishes a 6.0L engine is the 6.0 stamp on the engine block.
Q: What heads does LQ9 have?
The LQ9 has 317 or 035 cylinder heads. These cylinder heads are aluminum made, with a cathedral-shaped intake port and a D-port exhaust port. The cylinder head features a 210cc intake runner volume and 75cc exhaust runner volume.
Also, the cylinder heads are designed with an intake valve diameter of 2.000 in., 1.550 in. exhaust valve diameter, a combustion chamber of 71cc, and a Torque to Yield (TTY) cylinder head bolt style.
Q: What heads does a 5.3 have?
The 5.3L engines are equipped with 862-cylinder heads. The castings of cylinder heads are similar to that of 706 heads. 862 heads feature the following; 200cc intake runners, 1.890/1.550 in. valve combo, and 61cc combustion chamber volume.
The 5.3L 862 cylinder heads have a cathedral shape intake port and an oval shape exhaust port. The aluminum-made cylinder heads also feature an exhaust runner volume of 70cc. The 5.3L engine.
Q: What heads are on LQ4?
The 317 heads are designed to provide the LQ4 engines with a 9.4:1 static compression ratio. The cylinder heads perform incredibly on the LQ4 in synergy with the dished factory pistons.
The 317 cylinder heads feature the following; 71cc combustion chamber volume, cathedral shape intake port, D-port exhaust shape, 210cc intake runner volume, 75cc exhaust runner volume, 2.000 in. intake valve diameter, and 1.550 in. exhaust valve diameter.
The 317 heads are modeled similarly to the 243 heads found on LS2 or LS6. The LQ4 engines were equipped with 317 cylinder heads between 2001 and 2007. This was after they used 373 and 873 cylinder heads between 1999 and 2000.
Q: What is the difference between 821 and 823 heads?
The 821 and 823 cylinder heads are pretty much similar. However, the valves and springs are the slight distinguishing factor between the two.
The 823 rectangular port heads feature a lightweight valve combination of 2.165/1.590, as well as a peak flow of 223 cfm and 317 cfm on both the exhaust and intake, respectively. On the other hand, the 821 heads feature a valve combination of 2.180/1.600.
Q: How do I know if I have catch heads?
Catch heads have a casting number (706) on the lower right corner in the passenger area of the cylinder head. If you verify your vehicle’s cylinder heads and see “706,” it means your vehicle has Catch heads.
Catch distinguishes its cylinder heads from their counterparts by tagging a specific number to their cylinder head assembly. General Motors used Catch heads between 1999 and 2013 on their Silverado and Sierra 1500.
Final Words
This article has exposed various details about the 862 heads. You’ve just found out that the 862 cylinder heads are distinguished by the compression ratio, which is relatively higher than most cylinder heads’ compression ratios.
However, the sand cast, as well as the high possibility of experiencing a crack in the long run, is a major concern between 862 heads Vs. 243. The cracks can lead to coolant leaking into oil space, thereby resulting in severe engine damage.
If you intend to do a porting job on your car’s cylinder head, kindly consider the pros and cons of the 862 cylinder heads before making a final decision. After that, you can get 862 heads for sale on Amazon or any other outlet.