Most complete cam swap kits come with the correct valve springs.
If you are buying the parts separately there is a lot to consider.
Selecting the appropriate valve springs for an engine you're building involves considering several factors to ensure proper performance and durability. Valve springs are a critical component that control the movement of the engine's valves, affecting aspects such as valve timing, valve lift, and overall engine efficiency. Here's a step-by-step guide to help you determine the kind of valve springs you need:
1. Engine Specifications:
Start by gathering detailed specifications about the engine you're building. This includes information like the engine displacement, intended use (street, track, racing), target horsepower and RPM range, cylinder head type, valve sizes, and camshaft specifications. The valve springs you choose should be matched to these specifications.
2. Valve Lift and Camshaft Profile:
The camshaft profile and lift have a direct impact on the valve springs you need. A more aggressive camshaft with higher lift requires stiffer valve springs to prevent valve float at high RPMs. Refer to the camshaft manufacturer's specifications for recommended valve spring requirements.
3. RPM Range:
Consider the intended RPM range of your engine. Higher RPMs require stronger springs to ensure the valves close quickly and fully. Valve float occurs when the springs can't close the valves in time, potentially leading to power loss and engine damage.
4. Valve Weight:
The weight of the valves also affects spring selection. Heavier valves may require stronger springs to ensure they close properly and don't bounce.
5. Valve Material and Coatings:
The material and coatings used on the valves can affect the required spring pressure. Different materials expand and contract at different rates, impacting valve seat contact. Consult with your valve manufacturer for guidance.
6. Single vs. Dual Springs:
Depending on the engine's specifications, you might choose between single and dual valve springs. Dual springs provide more control and stability but can be more complex to set up.
7. Spring Pressure:
Determine the required spring pressure based on the factors mentioned above. This is typically measured in pounds per inch (lb/in) of spring compression. Camshaft manufacturers often provide recommendations for optimal spring pressure.
8. Spring Rate:
The spring rate is the amount of force required to compress the spring by a certain distance. It's usually provided in lbs/in. Calculate the required spring rate by considering the valve lift and other factors.
9. Valve Spring Material:
Valve springs are made from various materials like steel, titanium, and more. Each material has different characteristics in terms of strength, heat resistance, and weight. Choose a material that suits your engine's requirements.
10. Consult Experts:
If you're unsure about any aspect of valve spring selection, consult with engine builders, machine shops, or experts who have experience in building engines similar to yours. They can provide valuable insights and recommendations.
11. Trial and Testing:
Once you've selected valve springs based on the calculations and recommendations, it's a good idea to conduct thorough testing. Monitor valve behavior, RPM range, and overall engine performance to ensure that the selected valve springs are working as intended.
Remember that proper valve spring selection is crucial for engine longevity, performance, and reliability. Taking the time to carefully match the springs to your engine's specifications will pay off in the long run.