Inlet valve guide 1st oversize. Porsche 993 1994-98  ❭  99310432271

Exhaust valve guide 1st oversize.
This is a replacement intake valve guide - the small, cylindrical bushing within the cylinder head that guides the intake valve stem, ensuring correct alignment and smooth, controlled movement as the valve opens and closes. In some rebuild or re-machining scenarios, oversized guides are used to restore proper fit after head work.
Price is for each, 6 required per engine.

Fits:
Porsche 993 1994 - 1998

Diagram Ref no 3.

• Use Cases: Head rebuilds; valve-seat re-cut; restoring compressed guide bores; upgrading worn or damaged valve guides; preventive maintenance where valve guide integrity is uncertain.

• Supplied individually - multiple guides needed per head depending on engine (one per intake valve).

This valve guide keeps the intake valve moving in perfect alignment, ensuring proper sealing, efficient combustion, and stable engine performance. It supports the valve stem to prevent wobble or side movement that can cause uneven seat wear or loss of compression. Designed to withstand high RPM and heat, it promotes smooth valve operation and protects the valve, seat, and cylinder-head surfaces. As an oversize guide, it also restores correct fit in worn or re-machined heads, ensuring a safe and reliable rebuild.

Valve guides endure constant thermal cycles, valve-spring force, and high-speed motion. Over time they can wear, enlarge, or become loose - causing:
• Valve wobble and mis-alignment
• Poor sealing at valve seats - resulting in compression loss, misfires, or exhaust leakage
• Increased valve-stem wear, potential seat damage, or premature engine wear
• Reduced engine efficiency, elevated emissions, and unsafe reliability.

Replacing worn or oversized guides with a proper unit restores correct valve operation, extends cylinder-head life, ensures compression integrity, and brings the engine back to spec - critical for performance, reliability, and longevity.



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