RCM 14/14mm Cylinder Head Stud Kit



inc. vat / £419.99


inc. vat / €478.83


Designed for the ultimate in engine performance and reliability and derived from the rigors of the World Rally Championship, RCM’s 14mm/14mm Head Stud Kit has consistently proven itself as a must have component of any EJ20/22/25 engine build where 500bhp+ power output is expected. It is essential engines modified to this level have the most reliable system for clamping the cylinder heads onto the block assembly to avoid the heads lifting under load at high levels of boost pressure. The RCM 14/14mm Head Stud kit provides this peace of mind!

Now used in many of the fastest and most powerful Imprezas across the globe the RCM 14/14mm Head Stud Kit is quite simply the foundation on which all our high bhp engine conversions (including Gobstopper and Gobstopper 2) race engines are built around. Replacing the conventional 11mm Subaru cylinder head bolts with a series of 14mm precisely manufactured super high tensile, aircraft grade S99 steel stud and nut system offers many advantages when building your engine. With a tensile strength much higher than that of the OE bolts and the increased stability provided by the RCM studs larger diameter when further combined with the more uniform clamping force provided by the stud and nut arrangement it is clear why so many championship winning engines run these kits!

All kits are supplied with RCM's own assembly lube, which utilizes Graphite DJ technology, ensuring you are able to install to the correct torque figures accurately.

Ease of Fitment Guide


Download Fitting Instructions


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# technical specification

• Cylinder head studs manufactured using "Aircraft Grade S99 High Tensile Steel" to WRC specification.
• Precision rolled threads.
• Cylinder head stud thread pitch (Block End): M14X2.
• Cylinder head stud thread pitch (Cylinder Head end): M14X1.5.
• Cylinder head stud length: 197mm.


• Supplied in the kit are:


• x12 RCM 14mm head studs.
• x12 high tensile nuts.
• 1x Sachet of assembly lube and fitting guide for a comprehensive install.


• To allow fitting of the RCM 14/14mm Head stud kit your engine block must be re engineered to accept the larger studs used in this kit. RCM can carry this work out for you at  additional cost (see part number RCM237 or contact us for more details).

• Due to the increased diameter of the cylinder head stud machining is required to the cylinder heads. The original head bolt passages must be drilled out to a larger diameter in order for the 14mm stud to pass through. RCM can carry out this process for you if required (see part number RCM603 or contact us for more details).

Non RCM manufactured head gaskets used alongside this kit will require slight modification using our tapered reamer tool (See part number RCM910).

• 4x RCM658 modified head location dowels are required when using this kit (Sold separately).

# key features

• Huge increase in tensile strength and yield when compared with the OE head bolts.

• Massively increased clamping load for big bhp applications.

• Eliminates cylinder head lift at high levels of boost.

• Supplied with high tensile nuts, assembly lube and installation guide.

• As used in RCM Gobstopper I + II Time Attack race cars.

• Made in the UK from high tensile aircraft grade S99 steel to WRC spec.

• Precision rolled threads for maximum strength.

# confirmed applications

Suitable for all EJ20/22/25 series block cases.

If you are unsure of fitment then please check your engine code or contact our sales department.

# shipping

    Box Dimensions

    Dimensional Weight

    Actual Weight


25x11x10 cm

0.5 kg

3.3 kg

# other recommendations


RCM 14/12mm Cylinder Head Stud Kit


RCM EJ20 Multi Layer High Performance Cylinder Head Gasket


RCM EJ25 2006+ Multi Layer High Performance Cylinder Head Gasket


RCM Head Dowels for 14mm Stud Conversion

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