Engine Valves / Guides / Springs

Engine cylinder head inlet valve.



Fits:
Porsche 911 (993) 3.8 Carrera RS 1995-96 (M64.20)

Click 'Zoom in' for large parts diagram.
Diagram Ref No 9

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310540942

The product you are viewing cross references to these numbers

Engine Cylinder Head Inlet Valve.

The OE Match Engine Cylinder Head Inlet Valve is a precision replacement valvetrain component for the Porsche 911 (993) 3.8 Carrera RS. It controls the flow of intake air and fuel into the combustion chamber and provides an essential sealing surface when the valve closes against its seat.

Fits:

• Porsche 911 (993) 3.8 Carrera RS 1995-96 (M64.20)

Valve type: Inlet valve;
Valve head diameter: 51,50 mm;
Valve stem diameter: 8,00 mm;
Total length: 111,10 mm;
Valve seat angle: 45°;
Groove type: 3 groove;

Diagram Ref No 9

During the intake stroke, the valve opens to allow the cylinder to fill. It then closes against the valve seat so the combustion chamber can build and retain the compression required for efficient combustion.

Correct inlet valve condition, alignment and seating are essential for strong cylinder filling, consistent compression, smooth engine operation and reliable performance.

What This Product Does:

• Controls the intake of air and fuel into the combustion chamber.
• Opens during the intake stroke to allow the cylinder to fill.
• Closes against the valve seat to seal the combustion chamber.
• Helps maintain correct cylinder compression.
• Supports efficient airflow and combustion.
• Helps maintain strong throttle response and engine performance.
• Works with the valve guide, valve seat, spring and associated valvetrain components.
• Replaces an inlet valve that has become bent, burnt, pitted or excessively worn.
• Helps restore correct cylinder-head operation during an engine rebuild.

The valve must move smoothly within the valve guide and seat evenly around its circumference. Damage or wear that prevents complete seating can allow compression to escape and reduce engine efficiency.

Symptoms Of Wear Or Failure:

• Possible symptoms include:
• Low or uneven cylinder compression.
• Engine misfires.
• Rough or unstable idle.
• Reduced engine power.
• Poor acceleration or throttle response.
• Difficult starting.
• Increased fuel consumption.
• Uneven engine running.
• Ticking or abnormal valvetrain noise.
• Poor compression-test results.
• Leakage through the intake system during a leak-down test.
• Pitting or erosion of the valve face.
• Heavy carbon deposits around the valve.
• Bent or damaged valve stem.
• Excessive valve-stem wear.
• Failure of the valve to seal correctly against its seat.

A leaking inlet valve can allow compression pressure to escape back into the intake tract rather than remaining within the combustion chamber.

Why Replacement Matters:
The inlet valve plays a direct role in both filling and sealing the cylinder. If the valve becomes worn, bent, damaged or unable to seat correctly, combustion efficiency and cylinder compression can be affected.

Poor valve sealing can result in:

• Reduced engine power.
• Rough running and misfires.
• Poor starting.
• Uneven cylinder performance.
• Reduced combustion efficiency.
• Increased fuel consumption.
• Further wear to the valve and valve seat.

Replacing a defective inlet valve helps restore correct airflow, compression and combustion-chamber sealing.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310540942

The product you are viewing cross references to these numbers

Engine Cylinder Head Inlet Valve.
The OE Match Engine Cylinder Head Inlet Valve is a high-quality replacement valvetrain component designed to regulate the flow of air and fuel into the combustion chamber. Manufactured to OE specifications for fit, precision and durability, this inlet valve is essential for maintaining efficient combustion, engine performance and long-term reliability.  

Fits:

• Porsche 993 (911) C2 1994-97
• Porsche 993 (911) C4 1994-97
• Porsche 993 (911) TURBO 1994-96
• Porsche 993 (911) TURBO S 1994-97 

Diagram Ref No 9 

Constructed from premium-grade materials engineered to withstand continuous operation and high engine temperatures, the inlet valve works in conjunction with the camshaft, valve springs, valve guides and cylinder head assembly to control intake airflow with precise timing. Proper valve operation ensures optimal cylinder filling, efficient combustion and the responsive performance expected from a Porsche engine.  

What This Product Does:

• Controls the intake of air and fuel into the combustion chamber.
• Opens and closes in precise synchronisation with the engine cycle.
• Maintains an effective seal during compression and combustion.
• Supports efficient airflow and cylinder filling.
• Helps maximise engine power and throttle response.
• Contributes to fuel economy and emissions control.
• Forms a critical part of the engine valvetrain system.

Symptoms Of Wear Or Failure:

• Reduced engine power and acceleration.
• Rough idle or uneven engine operation.
• Engine misfires.
• Poor throttle response.
• Increased fuel consumption.
• Low compression in the affected cylinder.
• Difficulty starting the engine.
• Ticking or tapping noises from the cylinder head.
• Engine management warning lights or fault codes.
• Failed compression or leak-down test results.

Why Replacement Matters:

• Inlet valves operate continuously under demanding conditions and are subjected to thousands of opening and closing cycles every minute. Over time, exposure to heat, combustion deposits and mechanical wear can cause valves to become worn, bent, burnt, carbon-contaminated or develop sealing issues.
• A damaged inlet valve can restrict airflow into the combustion chamber, reducing combustion efficiency and negatively affecting engine performance. If left unresolved, valve-related problems can lead to compression loss, increased fuel consumption and potential damage to valve seats, cylinder heads and other internal engine components.
• Replacing a worn or damaged inlet valve restores proper airflow, improves combustion efficiency and helps maintain optimal engine performance. An OE Match replacement provides factory-style fitment, precision manufacturing and long-term durability, ensuring reliable operation and helping protect your Porsche engine from premature wear and costly repairs.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310540902

The product you are viewing cross references to these numbers

Engine cylinder head inlet valve. Price is for each.
Valve Head Ø: 50 mm, Valve Stem Ø: 8 mm, Valve Shaft Length: 110,4 mm, Valve Seat Angle: 45 °.



Fits:
Porsche 993 C2/C4 3.6L 1996-98
M64.21
M64.22
M64.23
M64.24

Click 'Zoom in' for large parts diagram.
Diagram Ref No 9.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310540502

The product you are viewing cross references to these numbers

Engine Cylinder Head Inlet Valve.

The OE Match Engine Cylinder Head Inlet Valve is a precision replacement valvetrain component for Porsche 911 (993) 3.6L Varioram engines. It controls the flow of the intake charge into the combustion chamber and provides an essential seal against the valve seat when closed.

Fits:

• Porsche 993 C2 / C4 3.6L 1996-98

M64.21
M64.22
M64.23
M64.24

Diagram Ref No 9

During the intake stroke, the valve opens to allow the cylinder to fill with air and fuel. It then closes firmly against the valve seat, sealing the combustion chamber so the engine can build and retain the compression required for efficient combustion.

Correct inlet valve condition, alignment and seating are essential for efficient cylinder filling, strong compression, smooth engine operation and consistent performance.

What This Product Does:

• Controls the intake of air and fuel into the combustion chamber.
• Opens during the intake stroke to allow efficient cylinder filling.
• Closes against the valve seat to seal the combustion chamber.
• Helps maintain correct cylinder compression.
• Supports efficient combustion and engine performance.
• Helps maintain responsive throttle operation and power delivery.
• Works with the valve guide, valve seat, valve spring and associated valvetrain components.
• Replaces an inlet valve that has become bent, pitted, burnt or excessively worn.
• Helps restore correct cylinder-head operation during engine rebuilding or refurbishment.

For correct operation, the valve must move smoothly within its guide and contact the valve seat evenly around its circumference. Wear or damage that prevents complete seating can allow compression to escape.

Symptoms Of Wear Or Failure:
Possible symptoms include:

• Low or uneven cylinder compression.
• Rough or unstable idle.
• Engine misfires.
• Reduced engine power.
• Poor acceleration or throttle response.
• Difficult starting.
• Increased fuel consumption.
• Uneven engine operation.
• Ticking or abnormal valvetrain noise.
• Poor compression-test results.
• Leakage through the intake system during a cylinder leak-down test.
• Pitting or erosion of the valve face.
• Carbon build-up around the valve.
• Bent or damaged valve stem.
• Excessive valve-stem wear.
• Failure of the valve to seal correctly against its seat.

A leaking inlet valve can allow cylinder pressure to escape back into the intake tract, reducing compression and combustion efficiency.

Why Replacement Matters:
The inlet valve performs two critical functions: allowing the cylinder to fill efficiently and sealing the combustion chamber when closed.

Over time, repeated valve movement, combustion temperatures, carbon deposits and mechanical wear can cause the valve face or stem to deteriorate. A valve may also become bent or damaged through mechanical contact or other internal engine problems.

A worn or damaged inlet valve can result in:

• Loss of cylinder compression.
• Reduced engine power.
• Rough running and misfires.
• Poor throttle response.
• Increased fuel consumption.
• Uneven performance between cylinders.
• Accelerated valve-seat wear.

Replacing a defective inlet valve helps restore the correct combustion-chamber seal, intake flow and cylinder compression.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310540502

The product you are viewing cross references to these numbers

Exhaust valve guide 1st oversize.
6 per engine. Price is for each.



Fits:
Porsche 993 Turbo 1994-98
Engine Type M64:60

Click 'Zoom in' for large parts diagram.
Diagram Ref no 2.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310432161

The product you are viewing cross references to these numbers

Exhaust valve guide 1st oversize.
6 per engine. Price is for each.



Fits:
Porsche 993 Turbo 1994-98
Engine Type M64:60

Material: Bronze
Inner diameter: 8,00 mm
Outer diameter: 13,05 mm
Length: 45,40 mm

Click 'Zoom in' for large parts diagram.
Diagram Ref no 2.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310432161

The product you are viewing cross references to these numbers

Exhaust Valve Guide 1st Oversize.

The TRW 1st Oversize Exhaust Valve Guide is a precision replacement component designed for the cylinder head of Porsche 911 (993) models. The guide supports the exhaust valve stem and keeps the valve accurately aligned as it opens and closes, helping the valve seat correctly and maintain an effective combustion-chamber seal.
x6 Per Engine.
Price Is For Each.

Fits:

• Porsche 993 (911) C2 1994-97
• Porsche 993 (911) C4 1994-97
• Porsche 993 (911) RS 1994-97
• Porsche 993 (911) C2S 1994-97
• Porsche 993 (911) C4S 1994-97  

Diagram Ref No 2

This 1st oversize version is intended for cylinder-head rebuilding where the original valve-guide bore has become worn or has been machined and a standard-size guide can no longer achieve the correct interference fit. Reference specifications list the guide as 8 x 13.26 mm. It is supplied individually, with six exhaust guides required for a complete engine.

What This Product Does:

• Supports and accurately guides the exhaust valve stem.
• Keeps the valve correctly aligned with its valve seat.
• Reduces excessive sideways movement and valve-stem wobble.
• Helps maintain effective cylinder sealing and compression.
• Assists with transferring heat from the exhaust valve stem into the cylinder head.
• Reduces abnormal loading and wear on the valve stem and valve seat.
• Provides an oversize external fit for cylinder heads requiring a 1st oversize guide.
• Helps restore correct valvetrain operation during a cylinder-head rebuild.

Correct valve guidance is particularly important on the exhaust side because exhaust valves and guides operate under very high thermal loads. Excessive clearance can prevent the valve from locating consistently against its seat and accelerate wear elsewhere in the cylinder head.

Symptoms Of Wear Or Failure:
A worn exhaust valve guide may cause:

• Blue or blue-grey exhaust smoke caused by oil entering the combustion chamber.
• Increased engine oil consumption.
• Excessive valve-stem play when inspected.
• Ticking or tapping noises from the cylinder head.
• Rough or uneven idle.
• Reduced engine performance or power.
• Poor or inconsistent compression.
• Engine misfires.
• Poor valve seating.
• Accelerated exhaust valve or valve-seat wear.
• Failed compression or leak-down test results.

As valve guides wear, their ability to accurately locate the valve against its seat decreases, which can compromise sealing and engine performance.

Why Replacement Matters:

• Exhaust valve guides are continually exposed to heat, friction and rapid valve movement. Over time, wear can increase the clearance between the valve stem and guide, allowing the valve to move laterally rather than travelling accurately along its intended path.
• Excessive valve movement can lead to poor valve seating, reduced compression, increased oil consumption and accelerated wear of the valve stem and valve seat. If left unresolved, the resulting wear can contribute to more extensive and expensive cylinder-head damage.
• Replacing worn guides restores controlled valve movement, supports consistent valve seating and helps protect the valve, valve seat and cylinder head. A correctly fitted guide also contributes to reliable compression, efficient exhaust-gas flow and long-term engine durability.
• The 1st oversize specification is especially important during cylinder-head refurbishment where the original guide bore has worn or been machined beyond standard dimensions. Using the correctly sized oversize guide allows the required secure fit to be restored.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310432172

The product you are viewing cross references to these numbers

Exhaust valve guide 1st oversize.
6 per engine. Price is for each.



Fits:
Porsche 993 1994-98

Click 'Zoom in' for large parts diagram.
Diagram Ref no 2.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310432172

The product you are viewing cross references to these numbers

Exhaust valve guide 1st oversize.
OE Match Exhaust Valve Guide is a precision-engineered valve guide designed to replace the original exhaust valve guide in the Porsche 911 (993) engine. This is a 1st oversize guide - meaning it is slightly larger than standard to accommodate engines that have been reamed or experienced wear over time.
Price is for each, 6 required per engine.

Fits:
Porsche 993 1994 - 1998

Diagram Ref no 2.

This exhaust valve guide keeps the exhaust valve stem perfectly aligned in the cylinder head, helping to ensure the valve seals correctly against the seat, maintains good compression, and promotes efficient evacuation of exhaust gases. A proper valve guide also helps conduct heat away from the valve stem into the head where it can be cooled by the engine’s coolant system.

Function:
• Valve Alignment: Ensures the exhaust valve travels straight and seats accurately each cycle.
• Wear Control: Reduces valve stem wobble and limits side loading that can damage seats or stems.
• Heat Conduction: Helps transfer combustion heat away from the valve stem and into the head casting.
• Rebuild Support: Oversize version is ideal for heads that have been reamed during rebuilds to restore correct fitment.

Fitment
•  Installed in the exhaust sides of the cylinder head valve train
•  Typically 6 guides per engine are needed for a full head rebuild.
•  This part matches Porsche’s oversize guide specification and is used when the standard guide bores have been worked to remove wear or damage.

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

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310432172

The product you are viewing cross references to these numbers

Exhaust valve guide 1st oversize.
6 per engine. Price is for each.



Fits:
Porsche 993 1994-98

Click 'Zoom in' for large parts diagram.
Diagram Ref no 3.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310432271

The product you are viewing cross references to these numbers

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.



Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310432271

The product you are viewing cross references to these numbers

Inlet Valve Guide 1st Oversize.

The TRW 1st Oversize Inlet Valve Guide is a precision replacement component for the cylinder head of Porsche 911 (993) models. The valve guide supports and accurately locates the inlet valve stem as the valve repeatedly opens and closes, keeping the valve correctly aligned with its seat.
x6 Per Engine.
Price Is For Each.

Fits:

• Porsche 993 1994-98

Diagram Ref No 3

Correct valve guidance is essential for smooth valve operation, effective combustion-chamber sealing and long-term cylinder-head reliability. The first-oversize specification is intended primarily for cylinder-head rebuilding or refurbishment where the original valve-guide bore has worn or been machined and a standard-size guide no longer provides the required interference fit.

What This Product Does:

• Supports and accurately guides the inlet valve stem.
• Prevents excessive sideways movement or valve wobble.
• Keeps the valve correctly aligned with the valve seat.
• Promotes consistent valve seating and combustion-chamber sealing.
• Helps protect the valve stem, valve seat and cylinder head from accelerated wear.
• Provides an oversize external fit for cylinder heads requiring a first-oversize valve guide during refurbishment.
• Helps restore correct valvetrain operation during a professional cylinder-head rebuild.

Symptoms Of Wear Or Failure:
Worn valve guides can allow excessive movement between the valve stem and guide. Possible symptoms include:

• Increased engine oil consumption.
• Blue exhaust smoke, particularly after start-up or during deceleration.
• Excessive valve-stem movement or valve wobble.
• Ticking or increased valvetrain noise.
• Poor or inconsistent valve seating.
• Reduced compression in an affected cylinder.
• Rough idle, misfires or reduced engine performance.
• Oil-fouled spark plugs.
• Accelerated valve-stem or valve-seat wear.
• Excessive valve-guide clearance discovered during cylinder-head inspection or rebuilding.

As guide wear increases, the valve may no longer locate accurately against its seat, potentially reducing combustion efficiency and contributing to further valve and cylinder-head wear.

Why Replacement Matters:

• Valve guides operate under constant heat, friction and rapid reciprocating movement. Once clearance becomes excessive, the valve can move laterally rather than travelling accurately along its intended axis. This can compromise valve seating, increase oil consumption and place additional stress on the valve stem and seat.
• Leaving badly worn guides in service can contribute to damaged valve seats, worn valve stems, poor sealing and potentially more extensive cylinder-head repairs. Installing the correct replacement guide restores controlled valve movement and helps maintain reliable compression, efficient combustion and long-term engine durability.
• The 1st oversize version is particularly important during cylinder-head refurbishment where the guide mounting bore can no longer securely retain a standard-size guide. Correct sizing and professional machining allow the replacement guide to achieve the required fit within the cylinder head.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99310432271

The product you are viewing cross references to these numbers

Valve lash adjuster fixture for Porsche 911



The established method of setting valve lash with a feeler gauge often provides for a "close enough" result and rarely provides for accurate, consistent, and easy to obtain precision. STOMSKI RACING's new version of an old-standby takes the "feel" out of setting valves and provides absolute precision, speed, ease of use, and consistency. By conveniently mounting a travel indicator over the adjuster of the rocker arm, STOMSKI RACING's 911 Valve Lash Adjuster allows you to quickly and accurately set and confirm the actual valve lash without settling for "close enough" or wondering whether your feel is consistent while trying to contort a feeler gauge into the far reaches of the 911 engine.

The SR097 is precision machined from 6061 aluminum and anodized for years of service on all 911 engines including 964s and 993s. Also available are a range of dial indicators including metric, digital, and compact travel indicators for use in restricted areas (pictured).

PLEASE NOTE:  this tool does not come with the gauge

Valve seat ring, inlet, oversize.



Fits:
Porsche 993 Carrera RS 1995-98

Click 'Zoom in' for large parts diagram.
Diagram ref no 4

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

96410433185

The product you are viewing cross references to these numbers

Valve seat ring, outlet, oversize.



Fits:
Porsche 993 Carrera RS 1995-98

Click 'Zoom in' for large parts diagram.
Diagram ref no 5

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

96410433585

The product you are viewing cross references to these numbers