🔍 Key Concepts

• Thermal expansion of engine components (valves, pushrods, cylinder head) as temperature increases • Differences in operating temperature between intake and exhaust valves during normal engine operation • Why manufacturers specify cold vs. hot valve clearances in maintenance manuals

💭 Think About

• Think about which valve (intake or exhaust) runs hotter in normal operation and how that affects its length when the engine is at operating temperature. • If both valves need the correct clearance when the engine is hot, what does that imply about how you must set their clearances when the engine is cold? • Consider what would happen to each valve’s clearance as the engine warms up from cold to normal operating temperature.

✅ Before You Answer

• Be clear on which components expand more with heat and how that changes the clearance (increases or decreases). • Verify in your mind which valve is exposed to hot exhaust gases and thus operates at a higher temperature. • Remember that the goal of setting cold clearances is to ensure proper clearance at operating temperature, not when cold.