Understanding GM LS-Series Cylinder Heads

Vehicle owners who have owned a car for more than a decade now are aware of most of the parts of a car’s engine and their functions. But it has been observed that ‘cylinder heads’ is the least attended topic, and most car owners have no idea about this part of an engine. Just like any other component, this is also a vital role player in the overall functioning of a vehicle. 

cylinder heads

General Motors had the most potent LS-series cylinder heads that were used in almost every vehicle of this car manufacturer, including Chevy, Pontiac, GMC, Cadillac, Hummer as well as Isuzu. In this post, we are trying to explore the in-depth facts about this LS cylinder heads series, but we will first go through the reasons why cylinder heads are there in our vehicles and why they are important, and what defects they can face.

Role of Cylinder Heads

Cylinder heads is responsible for closing the combustion chamber inside the engine from the top part. In other words, the upper part of your vehicle’s engine is given the name of the cylinder heads, and the lower part is called the engine block. A cylinder head would get placed on the top of the engine, and from there, it would work to keep the combustion chamber closed. Since the combustion chamber and the cylinder head are both made up of metal, the gap between them is often completed by another vital component called the head gasket. A cylinder head used in a gasoline engine has various vital parts, and a small list is presented here.

  • Inlet And Exhaust Ducts
  • Inlet And Exhaust Valves
  • Camshafts
  • Injectors
  • Spark Plugs

Here is a quick list of the components of LS cylinder heads used in diesel engines – 

  • Inlet And Exhaust Ducts
  • Inlet And Exhaust Valves
  • Camshafts
  • Injectors
  • Glow Plugs

This LS heads series introduced by General Motors had the most powerful and advanced LS cylinder heads. They were lightweight, made from aluminium, and designed to bolt up to LS engines. The power of these LS cylinder heads can be determined by the fact that they feature 259 CC intake and 102 CC exhaust runners. There were also 72 CC combustion chambers and 2.1 65″ intake, and a 1.600″ exhaust valve. The design is created in such a way that LS heads can assemble easily with valve springs, retainers, locks, guide plates, studs, and even seals. The outcome of this design was the benefits like economic availability yet maximum output. There were ported heads also mainly designed and produced in the form of fully assembled and heavy-duty components.

Here are some specs related to the torque generated by LS cylinder heads.

LS Cylinder Head Torque Specs

Engine Family

Bolt Size

First Pass

Second Pass

Final Pass

Gen. 3 (LS1, LS6, etc.)

M11 x 155.5mm

22 ft.-lbs.

90 degrees

90 degrees

M11 x 101mm

50 degrees

M8 x 46mm

22 ft.-lbs.

Gen. 4 (LS2, LS3, etc.)

M11 x 155.5mm

22 ft.-lbs.

90 degrees

70 degrees

M8 x 46mm

22 ft.-lbs.

These LS cylinder heads are compatible with most of the LS series engines manufactured by General Motors, and one of them is the LS7 engine. This engine comes with some high-end engine specifications like – 

  • Unique High-Flow
  • CNC-Ported
  • Square Port
  • Cylinder heads and intake are manifold in this series 
  • Intake valves are made up of titanium 
  • 1.8 ratio rockers are present 
  • The camshaft has a really long-duration high lift 
  • Deck plates are used for block machining performing to increase accuracy 
  • The oiling system is of a really high capacity and dry sump 

When all these features combine with the power of versatile LS heads, they can make an LS engine generate a whopping capacity of 7100 RPM.

How to Install LS Cylinder Heads? 

The first recommendation here is to rely upon highly established car mechanics for the same. They will follow a step-by-step approach for the installation procedure and ensure that an oil and coolant leak situation does not occur. Here is the detail of the installation process followed for installing LS cylinder heads.

Step – 1

The first step is to press new dowel pins into the engine blocks. There are two dowel pins per side in holes 7 and 8. They have to align the head to the block and this has to be done without fail before installing cylinder heads. To align the dowel pins perfectly, the team might have to tap them gently with a hammer.

Step – 2

Step 2 will involve cleaning the deck surface and placing the head gasket on the block while making sure that the appropriate direction is chosen.

Step – 3 

Again the deck surface of the LS head will have to be cleaned using a clean cloth and acetone, and then, the cylinder head is carefully placed on the head gasket. 

Step – 4

Now it’s time to install the bolt fingers really tight and when done, the task of LS 3 heads and LS1 heads installation is over.

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