🔍 Key Concepts

• Piston clearance / compression height in large low‑speed diesels • How connecting rod length and crank throw geometry affect piston position at TDC (top dead center) • What changing gasket thickness vs. bearing/shim thickness actually moves in the engine

💭 Think About

• Which component change will physically move the piston closer to or farther from the cylinder head when the crank is at TDC? • Does changing the cylinder head gasket thickness move the head, the piston, or both relative to the crankshaft centerline? • What effect does inserting shims at the crankpin bearing/connecting rod joint have on the effective length of the rod and thus on piston travel?

✅ Before You Answer

• Be clear on what “piston clearance from the cylinder head” means and when it is measured (TDC). • Identify which choices alter the effective connecting rod length versus which only affect bearing fit or gasket sealing. • Verify in your mind which actions are standard maintenance practices on large low‑speed marine diesels, and which sound mechanically incorrect or unsafe.