Cylinder head studs. Porsche 911 / 964 / 993 1965-98  ❭  99310117054

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Related, superseded, cross reference or alternative numbers for comparison.

99310117054

The product you are viewing cross references to these numbers