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Engine Bolts / Studs
By OE Match
Filter by brand
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- 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
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
Information
Cylinder head studs.
PACK OF 12. Normally 24 studs per engine.
Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1994-98
This product supersedes Porsche's old part numbers:
- 99310117051
Solves the problems of loose head studs, The exhaust leak you hear in the 911 may actually be the cylinder head leaking where the studs have pulled loose. As Porsche increased displacement of the 911 engine, the different rates of thermal expansion have caused head studs to break or pull out from the engine case.
Click 'Zoom in' for large parts diagram.
Diagram Ref No 2.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
PACK OF 12. Normally 24 studs per engine.
Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1994-98
This product supersedes Porsche's old part numbers:
- 99310117051
Solves the problems of loose head studs, The exhaust leak you hear in the 911 may actually be the cylinder head leaking where the studs have pulled loose. As Porsche increased displacement of the 911 engine, the different rates of thermal expansion have caused head studs to break or pull out from the engine case.
Click 'Zoom in' for large parts diagram.
Diagram Ref No 2.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
99310117051
99310117053
99310117054
The product you are viewing cross references to these numbers
About kit
This kit is comprised of the following items:
12 x Cylinder head studs. Porsche 911 / 964 / 993 1965-98 (99310117054/1
Price: £225.00
In stock
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- 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
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
Information
Cylinder head studs.
PACK OF 24. Normally 24 studs per engine.
Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1994-98
This product supersedes Porsche's old part numbers:
- 99310117051
Solves the problems of loose head studs, The exhaust leak you hear in the 911 may actually be the cylinder head leaking where the studs have pulled loose. As Porsche increased displacement of the 911 engine, the different rates of thermal expansion have caused head studs to break or pull out from the engine case.
Click 'Zoom in' for large parts diagram.
Diagram Ref No 2.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
PACK OF 24. Normally 24 studs per engine.
Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1994-98
This product supersedes Porsche's old part numbers:
- 99310117051
Solves the problems of loose head studs, The exhaust leak you hear in the 911 may actually be the cylinder head leaking where the studs have pulled loose. As Porsche increased displacement of the 911 engine, the different rates of thermal expansion have caused head studs to break or pull out from the engine case.
Click 'Zoom in' for large parts diagram.
Diagram Ref No 2.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
99310117051
99310117053
99310117054
The product you are viewing cross references to these numbers
About kit
This kit is comprised of the following items:
24 x Cylinder head studs. Porsche 911 / 964 / 993 1965-98 (99310117054/1
Price: £450.00
In stock
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- 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
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
Information
Dilavar head stud set.
This complete set of 24 Dilavar cylinder head studs replaces all major head fasteners on air-cooled Porsche flat-six engines. Ideal for full rebuilds, upgrades, or resolving broken stud issues, the set provides factory-spec strength, corrosion resistance, and thermal stability. Fits 911, 964, and 993 engines (1965–98).
SET OF 24 STUDS (Original Porsche Quality)
Fits:
Porsche 911 1965 - 1989
Porsche 964 1989 - 1994
Porsche 993 1994 - 1998
Diagram Ref No 2.
Aged factory head studs can crack, corrode, or lose tension - especially after decades of heat cycling. Failure of a head stud can cause head leaks, combustion pressure loss, broken cylinders, or catastrophic engine damage. Installing new Dilavar studs ensures proper sealing, correct torque values, and long-term engine reliability.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
This complete set of 24 Dilavar cylinder head studs replaces all major head fasteners on air-cooled Porsche flat-six engines. Ideal for full rebuilds, upgrades, or resolving broken stud issues, the set provides factory-spec strength, corrosion resistance, and thermal stability. Fits 911, 964, and 993 engines (1965–98).
SET OF 24 STUDS (Original Porsche Quality)
Fits:
Porsche 911 1965 - 1989
Porsche 964 1989 - 1994
Porsche 993 1994 - 1998
Diagram Ref No 2.
Aged factory head studs can crack, corrode, or lose tension - especially after decades of heat cycling. Failure of a head stud can cause head leaks, combustion pressure loss, broken cylinders, or catastrophic engine damage. Installing new Dilavar studs ensures proper sealing, correct torque values, and long-term engine reliability.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
99310117053
99310117051
99310117054
The product you are viewing cross references to these numbers
About kit
This kit is comprised of the following items:
24 x Dilavar head studs. Porsche 911 / 964 / 993 1965-98 (99310117054/8
Price: £660.00
In stock
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- 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
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
Information
Engine head stud, SET OF 12. Dilavar
A 12-piece Dilavar head stud set suitable for partial rebuilds, top-end refreshes, or replacing failed studs on one side of the engine. Provides the same high-strength, heat-stable performance as original Porsche Dilavar hardware. Fits air-cooled 911, 964, and 993 engines.
Fits:
Porsche 911 1965 - 1989
Porsche 964 1989 - 1994
Porsche 993 1994 - 1998
Diagram ref no 11
Aged factory head studs can crack, corrode, or lose tension - especially after decades of heat cycling. Failure of a head stud can cause head leaks, combustion pressure loss, broken cylinders, or catastrophic engine damage. Installing new Dilavar studs ensures proper sealing, correct torque values, and long-term engine reliability.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
A 12-piece Dilavar head stud set suitable for partial rebuilds, top-end refreshes, or replacing failed studs on one side of the engine. Provides the same high-strength, heat-stable performance as original Porsche Dilavar hardware. Fits air-cooled 911, 964, and 993 engines.
Fits:
Porsche 911 1965 - 1989
Porsche 964 1989 - 1994
Porsche 993 1994 - 1998
Diagram ref no 11
Aged factory head studs can crack, corrode, or lose tension - especially after decades of heat cycling. Failure of a head stud can cause head leaks, combustion pressure loss, broken cylinders, or catastrophic engine damage. Installing new Dilavar studs ensures proper sealing, correct torque values, and long-term engine reliability.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
99310117051
99310117053
The product you are viewing cross references to these numbers
About kit
This kit is comprised of the following items:
12 x Dilavar head studs. Porsche 911 / 964 / 993 1965-98 (99310117054/8
Price: £330.00
In stock
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 914 (1970-1976)
Information
Engine head studs SET OF 24 standard. Porsche 911 1965-73
24 per engine.
Fits:
Porsche 911 1965-1968 2.0L / 912 SWB (F)
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90110117203
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24 per engine.
Fits:
Porsche 911 1965-1968 2.0L / 912 SWB (F)
Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
(Not 1973 2.7L Carrera)
Porsche 914-6 1970-72
Diagram ref No 5
Related reference numbers
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90110117203
90110117203
The product you are viewing cross references to these numbers
About kit
This kit is comprised of the following items:
24 x Engine head studs standard. Porsche 911 1965-73 (90110117203/1
Price: £156.00
In stock
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
Information
Crankcase Through Bolt O-Ring
Sold each - 24 required per engine
The Porsche Crankcase Through Bolt O-Ring is a
small but critically important sealing component used in Porsche 911 engines
from 1965 to 1989. Fitted around the crankcase through bolts that secure the
engine case halves together, this O-ring helps prevent oil leakage from one of
the most common sealing points found on classic air-cooled Porsche engines.
Fits:
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
Diagram ref no 22
Although inexpensive, these O-rings play a vital role in maintaining the integrity of the engine lubrication system. When properly installed, they create a reliable seal around the through bolts, preventing pressurised engine oil from escaping the crankcase and helping to keep the engine clean and leak-free.
Whether you're performing a complete engine rebuild, repairing oil leaks, or restoring a classic Porsche 911, replacing the crankcase through bolt O-rings is considered essential preventative maintenance.
What Does the Crankcase Through Bolt O-Ring Do?
The through bolt O-ring seals the openings where the crankcase through bolts pass through the engine case.
Its primary functions include:
- Preventing oil leaks from the crankcase
- Maintaining crankcase sealing integrity
- Supporting proper oil system operation
- Helping preserve engine cleanliness
- Reducing oil loss and contamination
- Protecting engine components from oil seepage
Because Porsche air-cooled engines operate with a high-capacity dry-sump lubrication system, maintaining effective sealing throughout the crankcase is crucial for long-term reliability.
Why Does the Through Bolt O-Ring Fail?
Over time, the O-ring is exposed to extreme engine heat, oil, pressure fluctuations, and age-related deterioration.
Common causes of failure include:
- Rubber hardening due to heat cycles
- Age-related shrinkage
- Loss of elasticity
- Oil exposure over decades of use
- Improper installation
- Damage during assembly
- Long-term storage and inactivity
As the O-rings age, they gradually lose their sealing ability and become one of the most common sources of oil leaks on classic Porsche 911 engines.
Common Symptoms of a Failing Through Bolt O-Ring
Signs that the O-rings may require replacement include:
- Oil leaks around the crankcase
- Oil residue underneath the engine
- Persistent oil drips despite replacing other seals
- Oil staining around through bolt locations
- Excessive oil mist accumulation on the engine case
- Leaks becoming worse as the engine reaches operating temperature
These leaks are often mistaken for rocker cover, timing chain housing, or crankshaft seal leaks due to the way oil travels across the engine casing.
When Should You Replace It?
Replacement is strongly recommended whenever the engine is disassembled.
The through bolt O-rings should always be replaced:
- During complete engine rebuilds
- During crankcase splitting procedures
- When repairing major oil leaks
- During full engine restorations
- On high-mileage engines undergoing overhaul
- Whenever the crankcase through bolts are removed
- As preventative maintenance during engine refurbishment
Because access requires significant engine disassembly, replacing these O-rings during rebuild work is considered standard Porsche engine-building practice.
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99970100640
19805
99970100640
999.701.006.40
917.079
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Price: £0.85
In stock
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 914 (1970-1976)
Information
Crankcase through bolt washer.
Fits:
Porsche 911 1965-89
Porsche 914-6 1970-76
Click 'Zoom in' for large parts diagram.
Diagram ref no 23
Related reference numbers
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90110116103
The product you are viewing cross references to these numbers
Fits:
Porsche 911 1965-89
Porsche 914-6 1970-76
Click 'Zoom in' for large parts diagram.
Diagram ref no 23
Related reference numbers
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90110116103
90110116102
90110116103
90110116100
The product you are viewing cross references to these numbers
Price: £3.00
In stock
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 356B 1959-63
- Porsche 356C 1963-65
Information
Cylinder Head Nut
Sold each - 24 required for the 911
Maintain the integrity and reliability of your Porsche
engine rebuild with this OE Match Cylinder Head Nut 90110438204. Designed for
use on Porsche 356B, 356C, 912 and classic 911 air-cooled engines, this
precision-engineered fastener plays a critical role in securing the cylinder
head assembly to the engine.
Fits:
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 356B 1959-63
- Porsche 356C 1963-65
Diagram Ref No 17
Although small in size, cylinder head nuts are among the most important fasteners in any engine. They provide the clamping force required to maintain an effective seal between the cylinder heads, cylinders and engine case, ensuring correct compression, combustion efficiency and long-term engine reliability.
Manufactured to OE Match specifications, this cylinder head nut is ideal for engine rebuilds, top-end overhauls, cylinder head refurbishment and concours restorations.
What Does a Cylinder Head Nut Do?
The cylinder head nut secures the cylinder head assembly to the engine using the cylinder head studs.
Its primary functions include:
- Maintaining cylinder head clamping force
- Ensuring correct cylinder sealing
- Supporting combustion chamber integrity
- Maintaining engine compression
- Preventing cylinder head movement
- Supporting reliable engine operation
- Helping prevent oil and combustion leaks
Correct clamping force is essential for maintaining engine performance and durability.
Why Do Cylinder Head Nuts Fail?
Cylinder head nuts are exposed to repeated heat cycles, vibration and engine loads throughout their service life.
Common causes of deterioration include:
- Corrosion
- Thread wear
- Fatigue from repeated heat cycles
- Over-tightening
- Incorrect installation procedures
- Engine overheating
- Age-related degradation
- Damage during previous rebuilds
In older air-cooled Porsche engines, decades of service can leave original hardware weakened or unsuitable for reuse.
Symptoms of Worn or Damaged Cylinder Head Hardware
Potential warning signs include:
- Loss of cylinder sealing
- Compression leaks
- Oil seepage around cylinder heads
- Difficulty achieving correct torque settings
- Damaged threads
- Corroded hardware
- Uneven clamping loads
- Engine rebuild inspection failures
Many of these issues are discovered during engine disassembly rather than during normal operation.
When Should Cylinder Head Nuts Be Replaced?
Replacement is strongly recommended when:
- Rebuilding an engine
- Carrying out a top-end overhaul
- Replacing cylinder head studs
- Refurbishing cylinder heads
- Corrosion is present
- Threads show signs of wear
- Factory specifications require replacement
Most professional Porsche engine builders replace critical fastening hardware during major engine work to ensure long-term reliability.
Why Replacement Matters
Reusing worn or damaged cylinder head hardware can compromise engine sealing and reliability.
Benefits of replacement include:
- Correct clamping force
- Improved sealing performance
- Reduced risk of leaks
- Improved engine reliability
- Professional rebuild standards
- Long-term durability
- Factory-correct restoration quality
- Greater peace of mind
For classic Porsche engines, replacing critical hardware is inexpensive insurance against future engine issues.
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90110438204
90110438203
90110438202
61610438200
90110438200
93010438201
90110438204
The product you are viewing cross references to these numbers
Price: £2.35
In stock
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 356B 1959-63
- Porsche 356C 1963-65
Information
Cylinder head stud. Porsche 912 / 356B / 356C
Fits:
Porsche 912
Porsche 356 B
Porsche 356 C
Click 'Zoom in' for large parts diagram.
Diagram ref no 2
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53901118
The product you are viewing cross references to these numbers
Fits:
Porsche 912
Porsche 356 B
Porsche 356 C
Click 'Zoom in' for large parts diagram.
Diagram ref no 2
Related reference numbers
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53901118
53901118
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Price: £11.00
In stock
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- 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
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
Information
Cylinder head studs
This OE Match cylinder head stud is a replacement engine fastening stud for Porsche 911, 964, and 993 models from 1965 to 1998. It is designed to match the original-style fitment and function, helping secure the cylinder head and cylinder assembly correctly to the engine crankcase.
Sold individually, Normally 24 studs per engine
Fits:
Porsche 911 1965 - 1989
Porsche 964 1989 - 1994
Porsche 993 1994 - 1998
This product supersedes Porsche's old part numbers:
- 99310117051
Diagram Ref No 2.
The cylinder head stud provides the clamping force needed to hold the cylinder head, cylinder barrel, and engine case together. Correct head stud tension is essential for maintaining combustion sealing, cylinder stability, and reliable air-cooled engine operation.
Functions
• Secures the cylinder head and cylinder assembly to the engine case
• Provides correct clamping force for combustion sealing
• Supports cylinder and head alignment
• Helps maintain reliable engine sealing under heat and load
• Replaces corroded, stretched, broken, or damaged original studs
• Suitable for engine rebuilds, top-end repairs, and head stud replacement
• OE Match replacement for classic Porsche air-cooled engine repair
Why Replace This Part?
Cylinder head studs are exposed to high combustion forces, heat cycling, corrosion, vibration, and long-term engine load. Over time, studs can corrode, stretch, weaken, seize, or break. A damaged or broken head stud may cause compression leakage, oil seepage, cylinder head movement, exhaust leakage, poor running, or engine noise. Replacing worn or failed studs helps restore proper engine clamping and long-term reliability.
When to Replace This Part
• A cylinder head stud is broken, corroded, stretched, or damaged
• The engine has compression leakage or cylinder head sealing issues
• Oil seepage or combustion leakage is present around the cylinder/head area
• The engine is being rebuilt or overhauled
• The cylinder heads or barrels have been removed
• Existing studs are seized, heavily corroded, or unsuitable for reuse
• Preventative replacement is being carried out during top-end service.
Where it fits on the car
This cylinder head stud fits within the engine crankcase and extends through the cylinder barrel and cylinder head assembly. It forms part of the engine’s main cylinder/head fastening system and should be installed according to the factory engine layout and torque procedure.
Related reference numbers
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99310117054
The product you are viewing cross references to these numbers
This OE Match cylinder head stud is a replacement engine fastening stud for Porsche 911, 964, and 993 models from 1965 to 1998. It is designed to match the original-style fitment and function, helping secure the cylinder head and cylinder assembly correctly to the engine crankcase.
Sold individually, Normally 24 studs per engine
Fits:
Porsche 911 1965 - 1989
Porsche 964 1989 - 1994
Porsche 993 1994 - 1998
This product supersedes Porsche's old part numbers:
- 99310117051
Diagram Ref No 2.
The cylinder head stud provides the clamping force needed to hold the cylinder head, cylinder barrel, and engine case together. Correct head stud tension is essential for maintaining combustion sealing, cylinder stability, and reliable air-cooled engine operation.
Functions
• Secures the cylinder head and cylinder assembly to the engine case
• Provides correct clamping force for combustion sealing
• Supports cylinder and head alignment
• Helps maintain reliable engine sealing under heat and load
• Replaces corroded, stretched, broken, or damaged original studs
• Suitable for engine rebuilds, top-end repairs, and head stud replacement
• OE Match replacement for classic Porsche air-cooled engine repair
Why Replace This Part?
Cylinder head studs are exposed to high combustion forces, heat cycling, corrosion, vibration, and long-term engine load. Over time, studs can corrode, stretch, weaken, seize, or break. A damaged or broken head stud may cause compression leakage, oil seepage, cylinder head movement, exhaust leakage, poor running, or engine noise. Replacing worn or failed studs helps restore proper engine clamping and long-term reliability.
When to Replace This Part
• A cylinder head stud is broken, corroded, stretched, or damaged
• The engine has compression leakage or cylinder head sealing issues
• Oil seepage or combustion leakage is present around the cylinder/head area
• The engine is being rebuilt or overhauled
• The cylinder heads or barrels have been removed
• Existing studs are seized, heavily corroded, or unsuitable for reuse
• Preventative replacement is being carried out during top-end service.
Where it fits on the car
This cylinder head stud fits within the engine crankcase and extends through the cylinder barrel and cylinder head assembly. It forms part of the engine’s main cylinder/head fastening system and should be installed according to the factory engine layout and torque procedure.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
99310117051
99310117053
99310117054
The product you are viewing cross references to these numbers
Price: £18.75
In stock
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- 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
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
Information
Dilavar head studs.
Dilavar engine head studs are specialized fasteners used in the engines of certain Porsche models, especially air-cooled engines (like the 911). They are made from a proprietary alloy called Dilavar, which is designed to address specific thermal expansion and durability challenges in high-performance engines.
Price is each. Normally 24 studs per engine.
Fits:
Porsche 911 1965 - 1989
Porsche 964 1989 - 1994
Porsche 993 1994 - 1998
Diagram Ref No 2.
This product supersedes Porsche's old part numbers:
- 99310117051
Solves the problems of loose head studs, The exhaust leak you hear in the 911 may actually be the cylinder head leaking where the studs have pulled loose. As Porsche increased displacement of the 911 engine, the different rates of thermal expansion have caused head studs to break or pull out from the engine case. These latest Dilavar steel head studs have a thermal expansion rate of approximately the same as the alloy case.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
Dilavar engine head studs are specialized fasteners used in the engines of certain Porsche models, especially air-cooled engines (like the 911). They are made from a proprietary alloy called Dilavar, which is designed to address specific thermal expansion and durability challenges in high-performance engines.
Price is each. Normally 24 studs per engine.
Fits:
Porsche 911 1965 - 1989
Porsche 964 1989 - 1994
Porsche 993 1994 - 1998
Diagram Ref No 2.
This product supersedes Porsche's old part numbers:
- 99310117051
Solves the problems of loose head studs, The exhaust leak you hear in the 911 may actually be the cylinder head leaking where the studs have pulled loose. As Porsche increased displacement of the 911 engine, the different rates of thermal expansion have caused head studs to break or pull out from the engine case. These latest Dilavar steel head studs have a thermal expansion rate of approximately the same as the alloy case.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
99310117051
99310117053
99310117054
The product you are viewing cross references to these numbers
Price: £27.50
In stock
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- 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
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
- Porsche 996 TURBO 2000-05
- Porsche 996 GT2 2001-05
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
- Porsche 997 MK1 TURBO 2007-09
- Porsche 997 MK1 GT3 / GT3 RS 2007-09
- Porsche 997 MK1 GT2 2007-09
- Porsche 914 (1970-1976)
Information
Engine crankcase stud, BM8FO x 22.
Sold each.
Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1995-98
Porsche 996 Turbo 2001-05
Porsche 996 GT3 3.6L 1999-05
Porsche 997.1 Turbo 2007-09
Porsche 997 GT3 3.6L 2006-09
Porsche 914-6 1970-76
Click 'Zoom in' for large parts diagram.
Diagram ref no 4
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
90006010601
The product you are viewing cross references to these numbers
Sold each.
Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1995-98
Porsche 996 Turbo 2001-05
Porsche 996 GT3 3.6L 1999-05
Porsche 997.1 Turbo 2007-09
Porsche 997 GT3 3.6L 2006-09
Porsche 914-6 1970-76
Click 'Zoom in' for large parts diagram.
Diagram ref no 4
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
90006010601
99906200702
90006010601
The product you are viewing cross references to these numbers
Price: £3.98
In stock
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 914 (1970-1976)
Information
Engine case studs.
24 per engine. Price is for each.
Fits:
Porsche 911 1965-73
(Not 1973 2.7L Carrera)
Porsche 914-6 1970-72
Diagram ref No 5
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
90110117203
The product you are viewing cross references to these numbers
24 per engine. Price is for each.
Fits:
Porsche 911 1965-73
(Not 1973 2.7L Carrera)
Porsche 914-6 1970-72
Diagram ref No 5
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
90110117203
90110117203
The product you are viewing cross references to these numbers
Price: £6.50
In stock
DISPLAYING 1 to 13 (of 13 products)
Also found on these pages
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Crankcase 911 1965-69 101-05
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crankcase 912 1965-69 101-10
-
cylinder head, cylinder with piston 911 1965-69 103-00
-
cylinder head, cylinder with piston 912 1965-69 103-05
-
chain case, camshaft housing 911 1965-69 103-10
-
carburettor system with - SOLEX 40 PI-1 - for 911 UPTO 1968 107-06
-
injection system cylinder head and injection pump for 911 E/S 1969 onwards 107-20
-
vacuum system for clutch release for sportomatic for 911 L/S/TU upto 1968 and 911 T 1969 ONWARDS 107-30
-
replacement transmission, transmission case, chilled casting 911 1965-69 302-00
-
converter and converter housing sportomatic 911 1965-69 306-00
-
transmission case sportomatic 911 1965-69 307-00
About Engine Bolts / Studs
OEMatch Engine Bolts / Studs — Durability, Sealing, Performance
Engine bolts and studs are small but essential fasteners that secure cylinder heads, crankcases, connecting rods and manifolds on Porsche models. They maintain sealing, alignment and torque integrity during servicing, rebuilds and performance work; inspect fasteners for stretch, corrosion and thread damage during service.
Understanding OEMatch Engine Bolts / Studs
OEM (Original Equipment Manufacturer) parts are made by the same company that produced your Porsche’s original engine bolts / studs.
OE (Original Equipment) refers to parts matching original specifications for the engine bolts / studs and may be supplied by alternative manufacturers. Aftermarket parts offer alternative options, sometimes with enhanced features or better value. OEMatch supplies non-OEM engine bolts / studs engineered as direct-fit alternatives to OEM parts, made to original-spec dimensions and tolerances for Porsche models.
OE (Original Equipment) refers to parts matching original specifications for the engine bolts / studs and may be supplied by alternative manufacturers. Aftermarket parts offer alternative options, sometimes with enhanced features or better value. OEMatch supplies non-OEM engine bolts / studs engineered as direct-fit alternatives to OEM parts, made to original-spec dimensions and tolerances for Porsche models.
Engine fasteners must deliver consistent clamping force while resisting stretching, vibration and corrosion. They secure critical assemblies and preserve internal clearances. OEMatch supplies a wide selection of Porsche components, from gaskets to suspension hardware, engine parts and interior trim. The catalogue includes thousands of part numbers and cross-references and is continually expanded to support maintenance and restoration.
Benefits Include- Consistent clamping force and torque retention to preserve seals and clearances
- High fatigue resistance to resist loosening under repeated torque cycles
- Improved corrosion protection with suitable coatings or materials
- Metal fatigue or stretching from repeated torque applications
- Corrosion and oxidation, especially in high-heat or humid conditions
- Incorrect torque, over-tightening or under-torquing during installation
- Thread wear or damage from debris, cross-threading or improper handling
The Importance of Replacing with OEMatch Engine Bolts / Studs
During an engine rebuild or major service, replacing aged or stressed bolts and studs helps maintain sealing, alignment and torque integrity. Correct-grade fasteners reduce the risk of leaks, distortion and mechanical failure and support reliable long-term operation on Porsche engines. Where critical, follow model-specific specifications for material grade and torque values.Advantages
- Direct-fit replacements engineered to match original dimensions and tolerances for Porsche models
- Available in high-tensile and corrosion-resistant finishes to suit application requirements
- Precision threads for repeatable installation and reliable torque control
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