Engine Bolts / Studs

Engine casing kit.



Fits:
Porsche 911 2.7L to 3.2L & 930 3.3L

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504-9501

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Engine crankcase stud M8 X 78. 3 per engine. Price is for each.



Fits:
Porsche 911 1965-89 all models
Porsche 964 1989-94
Porsche 993 1995-98
Porsche 996 TURBO / GT3 1998-04
Porsche 997 TURBO / GT3 2005-12
Porsche 914 1970-76


Click 'Zoom in' for large parts diagram.
Diagram Ref No 6.

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90006010101

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Engine crankcase stud, BM 10 X 85.



Fits:
Porsche 911 1965-73
Porsche 911/911S / Carrera 2.7 1974-77
Porsche 914-6 1970-76

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Diagram ref no 16

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99906221701

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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

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90006010601

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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

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90006010601

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Engine crankcase stud, M 10 X 75.
Left



Fits:
Porsche 911 Turbo 1975-77

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Diagram ref no 6

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99906216502

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Engine crankcase stud, M8 x 52. RIGHT.
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 11

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90006010201

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Head stud height setter for Porsche 911



Precisely set the height of head studs on all the 911 engines using this innovative tool. The Delrin insert protects the engine case from scratches or marring, while the adjustable three-piece anodized aluminium tubular construction provides complete flexibility for all engine setups, tools, and stud combinations.

For all 911s including GT3s.

Engine Head Studs Cap Nut. 24  required per engine. 

Fits:
Porsche 911 1970-89

Click picture for large parts diagram.
Diagram Ref No 24.

Engine Head Studs Porsche 911 / 964 / 993 1965-98
Normally 24 studs per engine.

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.

Superior Tested/Proven strength. (compared to Dilavar & Raceware)

Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1994-98

This product supersedes Porsche's old part numbers:
- 993 101 170 51

Click picture for large parts diagram.
Diagram Ref No 2.

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99310117054

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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

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90110117203

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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

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90110117203

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Engine head studs upper standard. Price is for each.

Fits:
Porsche 911 1974-89 (12pcs Required)
Porsche 911 2.7L Carrera 1973 (24pcs Required)

Diagram Ref No 2

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91110117200

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Upper Head / Barrel Stud – Sold Each
12 required except 2.7 Carrera RS where 24 are required (upper and lower)

The Porsche Upper Head / Barrel Stud is a critical engine fastening component used in Porsche 911 models produced from 1973 to 1989. This stud forms part of the cylinder head retention system that secures the engine cylinders (barrels) and cylinder heads firmly to the crankcase, maintaining the precise clamping force required for reliable engine operation.

Fits:

• Porsche 911 1973 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 2

Porsche's air-cooled flat-six engines rely on these studs to withstand enormous combustion pressures and continuous thermal expansion cycles. Without adequate clamping force, cylinder sealing can be compromised, leading to compression loss, oil leaks, exhaust gas leakage, and costly engine damage.

For most Porsche 911 models within this period, 12 upper head studs are required. The notable exception is the legendary Porsche 2.7 Carrera RS, which requires a complete set of 24 studs.

Whether you're carrying out a top-end rebuild, complete engine overhaul, or concours restoration, replacing ageing head studs is an important step in maintaining long-term engine reliability.

What Does the Upper Head / Barrel Stud Do?

The upper head stud provides the clamping force that secures the cylinder head and cylinder barrel assembly to the engine crankcase.

Its primary functions include:

• Securing the cylinder heads to the engine case
• Maintaining correct cylinder sealing pressure
• Preserving combustion chamber integrity
• Preventing movement between cylinders and heads
• Supporting stable engine compression
• Maintaining long-term engine reliability

The stud is constantly under tension and plays a crucial role in preserving the structural integrity of the entire engine assembly.

Why Does the Head Stud Fail?

Head studs operate under extreme conditions, being subjected to continuous heat cycles, combustion forces, vibration, and material expansion and contraction.

Common causes of failure include:

• Metal fatigue
• Corrosion and oxidation
• Age-related material degradation
• Thermal cycling stress
• Engine overheating
• Improper torque procedures during previous rebuilds
• High-mileage wear Long-term mechanical loading

Even on well-maintained engines, decades of operation can weaken original studs and reduce their ability to maintain the required clamping force.

Common Symptoms of a Failing Head Stud

A damaged or broken head stud can result in:

• Compression leaks
• Exhaust gas leakage between the cylinder and head
• Ticking noises from the cylinder heads
• Oil seepage around the cylinder base
• Reduced engine performance
• Uneven cylinder sealing
• Failed leak-down test results
• Visible broken studs during valve cover inspection

In some cases, a broken head stud may go unnoticed until routine valve adjustment or engine rebuild work is carried out.

When Should You Replace Head Studs?

Head studs should always be inspected during major engine work and replaced whenever wear, corrosion, or damage is identified.

Replacement is highly recommended:

• During top-end rebuilds
• During complete engine overhauls
• When one or more studs have broken
• During cylinder head refurbishment
• On high-mileage engines
• During preventative restoration projects
• When upgrading engine performance
• Whenever the cylinder heads are removed

Because replacing head studs requires significant engine disassembly, many Porsche specialists recommend replacement while access is available.

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91110117200

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Engine head studs. Set of 24 head studs with nuts and washers.

SET OF 24
Head stud kit for Porsche 2.0L-3.8L air-cooled engines

Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1994-98

Diagram Ref No 2

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99310117054

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Exhaust head stud, L - 45mm. Made out of Titanium (Grade 5 Ti-6Al-4V)
Sold each.



Fits:
Porsche 911 3.2L 1984-89
Porsche 930 turbo
Porsche 965 turbo

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99906223902T

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