Leyland Grand Tourer Camshaft Secrets

The Leyland Grand Tourer, a name synonymous with classic British motoring, often sparks curiosity among enthusiasts regarding its intricate mechanical workings. A key component dictating an engine's character and performance is the camshaft. While the provided information focuses on the meticulous rebuilding process of A Series engines, it offers valuable insights into the quality of components and the philosophy behind achieving optimal results, which can be extrapolated to understand the likely camshaft specifications or the considerations for upgrading one in a Grand Tourer. This article will delve into what makes these engines tick, the importance of camshaft selection, and how the rebuild practices described contribute to a superior driving experience.

Understanding the Camshaft's Role

At its core, the camshaft is the brain of your engine's valve operation. It's a rotating shaft with lobes that push open the intake and exhaust valves. The shape and timing of these lobes, collectively known as the camshaft profile, directly influence several critical engine characteristics:

• Power Band: Where in the rev range the engine produces its peak power.
• Torque Delivery: How forcefully the engine pulls at different RPMs.
• Idle Quality: The smoothness or roughness of the engine at rest.
• Fuel Efficiency: How effectively the engine converts fuel into power.

For a 'Grand Tourer' designation, one typically expects a balance of performance and refinement. This suggests a camshaft designed for strong mid-range torque, allowing for effortless cruising and overtaking, rather than outright high-revving power, which might compromise low-speed drivability.

A Series Engine Rebuilding: A Commitment to Quality

The information provided highlights an unwavering dedication to quality in the reconditioning of A Series engines, which powered many Leyland vehicles, including likely variants of their grand tourer models. This commitment is crucial when considering any engine component, especially the camshaft.

New vs. Reconditioned Parts

The rebuilders emphasize using "all new replacement parts" alongside "reconditioned parts" that are rigorously "selected/inspected, chemically cleaned, re-inspected / crack-tested and manually finished before use." This meticulous approach ensures that even reconditioned components meet stringent standards. When it comes to camshafts, this means that whether a new or a carefully refurbished unit is used, its profile and material integrity are paramount.

Race Quality Components

A significant detail is the use of "race quality cam-followers in all of our builds." Cam followers, or tappets, are the components that ride on the camshaft lobes. Using race-quality ones, chosen for their "sized correctly and with a larger contact point for the lobe," indicates a focus on durability and reduced wear. This translates to a more reliable camshaft and potentially a longer lifespan for the entire valvetrain, even in a road-going Grand Tourer.

Competition and ARP Studs

The mention of "competition head studs in our standard and stage 1 builds and ARP studs in our Stage 2 upwards" further underscores the performance-oriented approach. Stronger head studs are necessary to withstand increased cylinder pressures, often a result of camshaft upgrades or other performance modifications. While not directly about the camshaft itself, it shows the context of builds that demand higher performance and reliability, hinting at the types of camshafts that might be employed in such scenarios.

What Camshaft for a Leyland Grand Tourer?

Directly stating the exact camshaft specification for a specific Leyland Grand Tourer model is challenging without precise model identification. However, based on the general characteristics of Grand Tourers and the A Series engine's capabilities, we can infer the likely intent:

• Standard Grand Tourer: A factory camshaft would typically be designed for a broad powerband, emphasizing torque from low to mid-range RPMs. This provides a smooth, responsive driving experience suitable for long journeys. The lobe separation angle would likely be wider, and lift and duration figures moderate.
• Performance-Oriented Grand Tourer: If a Grand Tourer was intended for a sportier feel, the camshaft might feature slightly more aggressive profiles. This could involve a narrower lobe separation angle for increased overlap (improving top-end power but potentially making the idle rougher) or increased lift and duration for better volumetric efficiency. The use of "stage 1" or "stage 2" upgrades mentioned in the rebuild description suggests that performance camshafts are a popular choice for enthusiasts looking to enhance their A Series engines.

Camshaft Specifications Explained (Typical A Series)

To illustrate, let's consider some common camshaft profiles used in A Series engines, keeping in mind that variations exist for different engine capacities (998cc, 1071cc, 1098cc, 1275cc):

Note: These are generalized figures and actual specifications can vary significantly between manufacturers and specific profiles. The "at 0.050" figures refer to the duration the valve is open at a specific lift point, a more precise measure of camshaft performance.

The Impact of Camshaft Choice on Your Grand Tourer

Choosing the right camshaft is a balancing act. A camshaft that provides exhilarating performance might make the car less comfortable for daily driving or long tours. Conversely, a camshaft optimized for smoothness and economy might lack the spirited response expected of a "Grand Tourer." The rebuilders' philosophy of using "race quality" components and offering "improved units" suggests that many owners opt for camshafts that offer a tangible performance enhancement while retaining good drivability.

Frequently Asked Questions

Q1: What is the primary difference between a standard and a performance camshaft for an A Series engine?

A1: A performance camshaft typically has lobes with greater lift (how far the valve opens) and longer duration (for how long the valve stays open). This allows more air and fuel into the cylinder and more exhaust gases out, boosting power, particularly at higher engine speeds. They often have a narrower lobe separation angle, which can increase the engine's torque but may make the idle less smooth.

Q2: Can I fit a performance camshaft to my standard Leyland Grand Tourer?

A2: Yes, you can. However, for optimal results and reliability, it's often recommended to consider complementary modifications. These might include upgrading the carburettor, exhaust system, and potentially the cylinder head. The rebuilders' approach of using competition head studs and race-quality cam followers suggests that these supporting modifications are crucial when aiming for performance gains.

Q3: How does camshaft choice affect fuel economy in my Grand Tourer?

A3: Generally, more aggressive camshaft profiles designed for higher performance tend to reduce fuel economy. This is because they are optimized for breathing at higher RPMs and may lead to less efficient combustion at lower engine speeds or during gentle driving. A camshaft with a wider lobe separation angle and moderate lift/duration is usually best for balancing performance and economy.

Q4: What are the benefits of using race quality cam followers?

A4: Race quality cam followers, as described, are designed for greater durability and precision. Their accurately sized contact points and larger surface area distribute the load from the camshaft lobe more evenly. This reduces wear on both the follower and the camshaft lobe, leading to increased engine longevity and more consistent valve operation, especially under higher stress.

Q5: How can I find out the exact camshaft specification for my specific Leyland Grand Tourer?

A5: The best way to determine the exact factory camshaft specification is to consult the original service manual for your specific Leyland Grand Tourer model. If you are considering an upgrade, reputable engine specialists or the rebuilders mentioned in the provided text can offer expert advice on suitable camshafts based on your desired performance characteristics and the engine's capacity.

Conclusion

While the precise camshaft fitted to every Leyland Grand Tourer might vary, the underlying principle for these classic vehicles, especially when considering engine rebuilds, is a commitment to quality and performance. The meticulous standards employed by engine specialists, including the use of high-quality components like race-spec cam followers and robust studs, ensure that whether a car is kept in original specification or upgraded, its heart beats with reliability and vigour. For those seeking to enhance their Grand Tourer's character, understanding the role of the camshaft and selecting a profile that matches their driving aspirations is key to unlocking the full potential of these beloved British classics.