Connecting bridge 原装 Porsche 零部件 99310439100

排气阀导管1 号超尺寸。
这套包含6个进气门导管（第一个为加大尺寸）的套装专为保时捷993风冷水平对置六缸发动机的专业气缸盖翻新而设计。这些导管按照保时捷原厂尺寸、材料规格和硬度等级制造，确保进气门以正确的对准、稳定性和密封性能运行——所有这些对于维持正常的燃烧和发动机的长期可靠性都至关重要。
一套6件

适用：
保时捷 993 1994 - 1998

图示编号 3。

•应用案例：缸盖重建；气门座重新切割；修复压缩的导管孔；升级磨损或损坏的气门导管；气门导管完整性不确定时的预防性维护。

当气缸盖导管孔磨损或在翻新过程中被加工过时，需要使用加大尺寸的气门导管。这套导管包含一套完整的匹配进气导管，确保所有气缸的配合一致，并实现精准的气门控制。这些与原厂规格相同的导管采用精密加工工艺，具有优异的耐热性，能够使气门机构恢复到出厂时的状态，消除过大的气门间隙，防止压缩损失、失火或过早磨损。

对于发动机重建者、修复者以及任何翻新 993 气缸盖的人来说，这套组件堪称完美之选。它支持平稳、精确的阀门运动，并在保时捷风冷高性能发动机特有的高温和高转速条件下实现最佳密封。

气门导管承受着持续的热循环、气门弹簧力和高速运动。随着时间的推移，它们可能会磨损、膨胀或松动，从而导致：
•阀门晃动和错位
•气门座密封不良——导致压缩损失、失火或排气泄漏
•气门杆磨损加剧、气门座可能损坏或发动机过早磨损
•发动机效率降低、排放量增加、可靠性不安全。

用合适的导管替换磨损或过大的导管，可以恢复正确的阀门操作，延长气缸盖寿命，确保压缩完整性，并使发动机恢复到规格——这对性能、可靠性和使用寿命至关重要。



相关参考编号
相关编号、被取代编号、交叉引用编号或替代编号，供比较之用。

99310432271

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Exhaust valve guide - 1st oversize - set.
This is a set of six OE Match quality exhaust valve guides designed for the air-cooled Porsche 911 (993) engines produced between 1994 and 1998. These are 1st oversize valve guides, meaning they are slightly larger than standard guides to accommodate engines that have been reamed or show wear in the original guide bores. The set contains six guides, enough for a full cylinder head rebuild on the exhaust side.
SET OF 6

Fits:
Porsche 993 1994 - 1998

Diagram Ref no 2.

Valve guides are precision metal bushings pressed into the cylinder head that support and guide the movement of the exhaust valve stems. Over time, original guides can wear, allowing excessive valve stem play, reducing seal effectiveness, and increasing engine oil consumption. These OE Match valve guides are manufactured to match Porsche’s original specifications, including diameter, material quality and machining tolerance, but in a 1st oversize dimension so they fit reamed cylinder heads.

This SET OF 6 provides a complete set for one engine’s exhaust side - ideal for cylinder-head rebuilds, valve jobs or whenever the exhaust guide bores are undersized due to wear.

The exhaust valve guides:
•  Support and align the exhaust valve stems so they travel accurately within the head.
•  Maintain correct valve seating and combustion sealing, which is vital for performance and compression.
•  Help conduct and dissipate heat from valves into the cylinder head casting.
•  Reduce lateral valve stem movement, decreasing wear on stems and valve seats.

By replacing old or worn guides with a matched oversize set, you can restore tight tolerances in the valve train and help ensure efficient combustion and long-term reliability.

Valve guides wear over time due to heat, friction, and repeated valve movement. When guides become worn or oversized gaps develop between the valve stem and guide bore, the following issues can arise:
•  Loss of performance and power
•  Higher oil consumption
•  Reduced sealing and compression
•  Increased valve train wear

Installing a correct OE Match valve guide restores correct valve alignment, reduces unwanted movement, supports proper seat sealing, and prolongs the life of your engine’s top end - especially in rebuild or high-mileage applications.

Replace valve guides if you observe:
•  Blue smoke from the exhaust (signifying oil burning)
•  Rough idle or hesitation
•  Poor compression or loss of engine power
•  Valve stem play when checked during teardown
•  During a cylinder head rebuild or valve job

相关参考编号
相关编号、被取代编号、交叉引用编号或替代编号，供比较之用。

99310432172

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