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- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 356C 1963-65
Fits:
Porsche 356C 1600 / SC
Porsche 912
Suitable for late type heads (30 degree) – Titanium Grade 2 and race proven
Diagram ref no 13
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
61610542201
The product you are viewing cross references to these numbers
- Porsche 993 (911) C2 1994-97
- Porsche 993 (911) C4 1994-97
- Porsche 993 (911) C2S 1994-97
- Porsche 993 (911) C4S 1994-97
The OE Match exhaust valve is a precision engine component designed for Porsche 911 (993) Carrera models equipped with early 3.6L engines. It is installed in the cylinder head and forms part of the valve train responsible for controlling the flow of exhaust gases from the combustion chamber to the exhaust system.
Sold individually, 6 required per vehicle
Fits:
Porsche 993 C2 / C4 3.6L 1993 - 1995
* with Engine codes: M64.05 / M64.06 / M64.07 / M64.08
Diagram Ref No 10
The OE Match version of part number 99310541901 is designed for pre-Varioram Porsche 993 engines used in early Carrera models. It is engineered with the correct stem diameter, valve head size and material specification to withstand the extreme temperatures and stresses experienced in high-performance air-cooled engines.
The exhaust valve regulates the release of burnt gases from the combustion chamber. When opened at the correct time by the camshaft, it allows exhaust gases to exit the cylinder and enter the exhaust system, preparing the chamber for the next intake cycle.
Maintaining properly functioning valves is essential for efficient combustion, engine power and reliable operation.
Exhaust valves operate under extremely high temperatures and continuous mechanical stress. Over time they may wear, warp or suffer from carbon buildup, which can lead to compression loss, poor engine performance or valve train noise. Replacing worn valves during engine service or rebuild ensures proper combustion sealing and reliable engine operation.
Consider replacing the exhaust valve if you notice:
• Loss of compression or engine power
• Excessive valve train noise
• Burnt or worn valve surfaces
• During cylinder head rebuild or engine overhaul
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310541901
The product you are viewing cross references to these numbers
- 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
Exhaust Valve - Varioram
Engines
Sold each - 6 required per car
Maintain the performance, efficiency and reliability of your
Porsche 993 Varioram engine with this OE Match Exhaust Valve.
Designed specifically for Porsche 993 Varioram engines including M64.21,
M64.22, M64.23 and M64.24 engine variants, this exhaust valve plays a critical
role in the combustion process by allowing spent exhaust gases to exit the
combustion chamber efficiently.
Fits:
- Porsche 993 (911) C2 1996-97
- Porsche 993 (911) C4 1996-97
- Porsche 993 (911) RS 1996-97
- Porsche 993 (911) C2S 1996-97
- Porsche 993 (911) C4S 1996-97
Diagram Ref No 10
Operating under extreme temperatures and pressures, exhaust valves are among the hardest-working components within the engine. During every combustion cycle, they must withstand intense heat while maintaining an effective seal against the valve seat to preserve compression, power output and engine efficiency.
Manufactured to OE Match specifications, this exhaust valve is ideal for engine rebuilds, cylinder head refurbishment, top-end overhauls and preventative maintenance projects.
Technical Specification
Valve
Head Diameter: 43.50 mm
Valve
Stem Diameter: 8.00 mm
Valve
Shaft Length: 109.00 mm
Valve
Seat Angle: 45°
Suitable
for Porsche 993 Varioram engines:
M64.21
M64.22
M64.23
M64.24
What Does the Exhaust Valve Do?
The exhaust valve is responsible for controlling the exit of combustion gases from the cylinder.
Its primary functions include:
- Releasing burnt exhaust gases
- Maintaining combustion chamber sealing
- Supporting efficient engine breathing
- Preserving compression
- Assisting engine performance
- Supporting fuel efficiency
- Maintaining smooth engine operation
Correct exhaust valve operation is essential for maintaining the power and responsiveness expected from the Porsche 993 Varioram engine.
Why Do Exhaust Valves Fail?
Exhaust valves are exposed to some of the harshest operating conditions within the engine.
Common causes of failure include:
- Extreme heat exposure
- Valve seat wear
- Carbon build-up
- High mileage wear
- Detonation damage
- Valve guide wear
- Overheating
Over time, valves can become worn, burnt, pitted or damaged, reducing their ability to seal effectively.
Symptoms of a Worn or Damaged Exhaust Valve
Common warning signs include:
- Reduced engine compression
- Loss of power
- Rough idle
- Increased exhaust emissions
- Misfires
- Excessive oil consumption
- Poor throttle response
- Unusual engine noise
In severe cases, a burnt valve can significantly affect engine performance and drivability.
When Should Exhaust Valves Be Replaced?
Replacement is recommended when:
- Carrying out a cylinder head rebuild
- Performing a top-end engine overhaul
- Valve seat damage is present
- Compression loss is identified
- Burnt valves are discovered
- Valve stem wear exceeds specifications
- Rebuilding a high-mileage engine
- Completing a full engine restoration
Professional engine builders routinely inspect and measure all valves during rebuild work.
Why Replacement Matters
A worn exhaust valve can compromise engine performance, reliability and efficiency.
Benefits of replacement include:
- Restored compression
- Improved power delivery
- Better engine efficiency
- Smoother operation
- Improved combustion quality
- Reduced emissions
- Increased engine reliability
- Long-term engine protection
Replacing worn valves during a rebuild helps ensure the longevity of expensive engine components.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310541906
The product you are viewing cross references to these numbers
- 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
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