Please wait… 
Please wait while we process your order,
do not press the back button…
do not press the back button…
Enter your VAT number here and click Verify:
Your details have been verified. VAT number registered to:
,
.
Your order will now be zero rated for VAT purposes. We reserve the right to verify these details after your order request has been made and reinstate VAT if required.
Your VAT details were not recognised or were invalid. Your VAT number must be matched to your Billing Country as specified above. This is currently specified as . You do not need to enter the country code part of your VAT number as this has already been selected in your billing address details above.
The VAT number checking service is currently offline. Please supply your VAT details within the comments or special instructions field below and we will apply a VAT discount after placing your order request.
Part Categories +
- Accessories
- Brakes
- Chassis / Bodywork
- Clothing & Gifts
- Electrical & Relays
- Engine Cooling
- Engine Electrical
- Engine Rebuild Parts
- Engine Tuning
- Exhausts
- Exterior Styling / Spoilers
- Gearbox / Transmission
- Heating / Air Conditioning
- Hydraulics
- Incar / Multimedia
- Interior & Accessories
- Lighting
- Mats & Carpets
- Motorsport and Off-Road
- Parts for Other Cars
- Pedal Cluster
- Rubber Seals
- Seats & Seat Belts
- Service Parts
- Special Offer Parts
- Steering Parts
- Suspension & Axle
- Suspension Upgrades
- Tyres
- Wheel Accessories
- Wheels
adjusting washer Genuine Porsche part 99903105240
Code: 99903105240
Genuine Porsche part
adjusting washer
The product code 99903105240 was also found on these diagrams
Additional information:
• This part is brand new and unused.
• Please verify that it is 100% suitable for your specific vehicle before purchase to ensure compatibility.
Before purchasing thoroughly check part to confirm compatibility.
• This part is brand new and unused.
• Please verify that it is 100% suitable for your specific vehicle before purchase to ensure compatibility.
Before purchasing thoroughly check part to confirm compatibility.
Vehicle Group
- We are unable to provide fitting details for this product at this time. Please contact us for further information.
Price: £3.07
Orderable - 14 - 28 Days
Related products
99903109101
Product Information
Fits:
Porsche 911 1978-89
Diagram Ref No 16
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903109101
The product you are viewing cross references to these numbers
Product Information
Head nut washer. 24 per engine. Price is for each.Fits:
Porsche 911 1978-89
Diagram Ref No 16
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903109101
99903109101
911026
The product you are viewing cross references to these numbers
Vehicle Group
Vehicle Group
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1978-1989 3.3L Turbo (930)
Price: £9.90
Orderable - 14 to 28 Days
Shop Securely
12 Month Warranty
Worldwide Delivery
99903106202
Product Information
Fits:
Porsche 356 (1950 to 1965)
Porsche 912 (1965 to 1969)
Click 'Zoom in' for large parts diagram.
Diagram ref no 17
Price is for each.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903106202
The product you are viewing cross references to these numbers
Product Information
Washer 10.5x19x2.0 for screwing the cylinder head.Fits:
Porsche 356 (1950 to 1965)
Porsche 912 (1965 to 1969)
Click 'Zoom in' for large parts diagram.
Diagram ref no 17
Price is for each.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903106202
99903106202
The product you are viewing cross references to these numbers
Vehicle Group
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 356 1950-55
- Porsche 356A 1955-59
- Porsche 356B 1959-63
- Porsche 356C 1963-65
Price: £4.30
In Stock - 24 Hour Dispatch
Shop Securely
12 Month Warranty
Worldwide Delivery
Express Delivery
99903109101/1
Product Information
This washer is used under the cylinder head nuts on Porsche 911 engines (1978–1989). It’s a precision washer made to the same style and dimensions as the original, helping the head nut seat correctly against the engine hardware.
Price is for each, 24 required per engine.
Fits:
Porsche 911 1978 - 1989
Diagram ref no 16
The washer spreads the clamping load from the head nut, helping maintain consistent torque retention and protecting mating surfaces from damage caused by concentrated pressure.
• It’s supplied per washer (price is for each) and 24 washers are required per engine.
It provides a stable, even load surface beneath each head nut, supporting correct tightening and helping the cylinder head fastening system maintain consistent clamp force over time - especially important on engines that see repeated thermal expansion and contraction.
• Distributes head nut load to reduce point-stress on components
• Helps maintain more consistent clamping force as the engine heat-cycles
• Supports proper seating of the head nut for reliable assembly during rebuilds
Old washers can become corroded, deformed, or marked from previous torque cycles. Reusing tired hardware can affect how evenly the head nuts clamp, which can compromise long-term sealing and reliability. Fresh washers help restore proper seating and load distribution during rebuild work.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903109101
The product you are viewing cross references to these numbers
Product Information
Cylinder head nut washer (Head nut washer) This washer is used under the cylinder head nuts on Porsche 911 engines (1978–1989). It’s a precision washer made to the same style and dimensions as the original, helping the head nut seat correctly against the engine hardware.
Price is for each, 24 required per engine.
Fits:
Porsche 911 1978 - 1989
Diagram ref no 16
The washer spreads the clamping load from the head nut, helping maintain consistent torque retention and protecting mating surfaces from damage caused by concentrated pressure.
• It’s supplied per washer (price is for each) and 24 washers are required per engine.
It provides a stable, even load surface beneath each head nut, supporting correct tightening and helping the cylinder head fastening system maintain consistent clamp force over time - especially important on engines that see repeated thermal expansion and contraction.
• Distributes head nut load to reduce point-stress on components
• Helps maintain more consistent clamping force as the engine heat-cycles
• Supports proper seating of the head nut for reliable assembly during rebuilds
Old washers can become corroded, deformed, or marked from previous torque cycles. Reusing tired hardware can affect how evenly the head nuts clamp, which can compromise long-term sealing and reliability. Fresh washers help restore proper seating and load distribution during rebuild work.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903109101
99903109101
The product you are viewing cross references to these numbers
Vehicle Group
Vehicle Group
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1978-1989 3.3L Turbo (930)
Price: £2.95
In Stock - 24 Hour Dispatch
Shop Securely
12 Month Warranty
Worldwide Delivery
Express Delivery
99903108302/1
Product Information
This OE Match washer for the cylinder head nut is a replacement engine fastening washer for Porsche 911 models from 1965 to 1977 and Porsche 914-6 models. It is designed to match the original-style fitment and support correct cylinder head nut clamping.
Sold individually
Fits:
Porsche 911 1965 - 1977
Porsche 930 Turbo 1975 - 1977
Porsche 914-6
Diagram ref no 17
The washer sits beneath the cylinder head nut and helps distribute the clamping load evenly across the mounting surface. This supports correct fastening of the cylinder head assembly and helps protect the mating surfaces from damage during tightening.
Functions
• Fits beneath the cylinder head nut
• Helps distribute cylinder head nut clamping force
• Supports correct cylinder head fastening
• Helps protect the mounting surface from nut damage
• Replaces worn, missing, corroded, or damaged original washers
• Suitable for engine rebuilds, cylinder head work, and top-end servicing
• OE Match replacement for classic Porsche engine repair.
Why Replace This Part?
Cylinder head nut washers can become worn, distorted, corroded, marked, or damaged during removal and refitting. Reusing damaged washers can affect clamping consistency or damage the mounting face. Replacing the washer during cylinder head service or engine rebuild helps ensure the fastener seats correctly and supports reliable engine assembly.
When to Replace This Part
• The cylinder head nuts have been removed
• The original washer is missing, worn, corroded, or distorted
• The washer face is marked, damaged, or no longer flat
• Cylinder head work or top-end engine service is being carried out
• The engine is being rebuilt or restored
• Correct fastening hardware is required for an OE-style rebuild
• Preventative replacement is being carried out during engine assembly.
Where it fits on the car
This washer fits in the engine cylinder head fastening assembly, positioned beneath the cylinder head nut on Porsche 911 and 914-6 models.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903108302
The product you are viewing cross references to these numbers
Product Information
Washer for cylinder head nutThis OE Match washer for the cylinder head nut is a replacement engine fastening washer for Porsche 911 models from 1965 to 1977 and Porsche 914-6 models. It is designed to match the original-style fitment and support correct cylinder head nut clamping.
Sold individually
Fits:
Porsche 911 1965 - 1977
Porsche 930 Turbo 1975 - 1977
Porsche 914-6
Diagram ref no 17
The washer sits beneath the cylinder head nut and helps distribute the clamping load evenly across the mounting surface. This supports correct fastening of the cylinder head assembly and helps protect the mating surfaces from damage during tightening.
Functions
• Fits beneath the cylinder head nut
• Helps distribute cylinder head nut clamping force
• Supports correct cylinder head fastening
• Helps protect the mounting surface from nut damage
• Replaces worn, missing, corroded, or damaged original washers
• Suitable for engine rebuilds, cylinder head work, and top-end servicing
• OE Match replacement for classic Porsche engine repair.
Why Replace This Part?
Cylinder head nut washers can become worn, distorted, corroded, marked, or damaged during removal and refitting. Reusing damaged washers can affect clamping consistency or damage the mounting face. Replacing the washer during cylinder head service or engine rebuild helps ensure the fastener seats correctly and supports reliable engine assembly.
When to Replace This Part
• The cylinder head nuts have been removed
• The original washer is missing, worn, corroded, or distorted
• The washer face is marked, damaged, or no longer flat
• Cylinder head work or top-end engine service is being carried out
• The engine is being rebuilt or restored
• Correct fastening hardware is required for an OE-style rebuild
• Preventative replacement is being carried out during engine assembly.
Where it fits on the car
This washer fits in the engine cylinder head fastening assembly, positioned beneath the cylinder head nut on Porsche 911 and 914-6 models.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903108302
99903108302
99903108301
The product you are viewing cross references to these numbers
Vehicle Group
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 1975-1977 3.0L Turbo (930)
- Porsche 914 (1970-1976)
Price: £2.00
Due In 12 Days
Shop Securely
12 Month Warranty
Worldwide Delivery
99903108302
Product Information
Fits:
Porsche 911 1965-77
Porsche 930 Turbo 1975-77
Porsche 914-6
Click 'Zoom in' for large parts diagram.
Diagram ref no 17
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903108302
The product you are viewing cross references to these numbers
Product Information
Washer for cylinder head nut. Fits:
Porsche 911 1965-77
Porsche 930 Turbo 1975-77
Porsche 914-6
Click 'Zoom in' for large parts diagram.
Diagram ref no 17
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903108302
99903108302
99903108301
The product you are viewing cross references to these numbers
Vehicle Group
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 1975-1977 3.0L Turbo (930)
- Porsche 914 (1970-1976)
Price: £5.88
In Stock - 24 Hour Dispatch
Shop Securely
12 Month Warranty
Worldwide Delivery
Express Delivery
99903108302/1KIT
Product Information
This OE Match kit is a complete cylinder head fixing set consisting of 24 washers and 24 nuts. It is designed for use during cylinder head assembly, engine rebuilding, or restoration where the listed part numbers are specified.
Sold as a complete 48-piece set containing 24 washers and 24 cylinder head nuts
Fits:
Porsche 911 1965 - 1977
Porsche 930 Turbo 1975 - 1977
Porsche 914-6
Diagram ref no 17
The cylinder head nuts and washers secure the cylinder heads correctly to the engine studs. The washers help distribute clamping load beneath the nuts, while the nuts provide the required fastening force to hold the cylinder heads securely in position.
Functions:
• Replaces cylinder head nuts and washers
• Complete 48-piece set
• Includes 24 cylinder head washers
• Includes 24 cylinder head nuts
• Helps distribute cylinder head clamping load correctly
• Supports secure cylinder head installation
• Suitable for engine rebuilding and restoration
Why Replace This Set?
Cylinder head nuts and washers are subjected to high clamping loads, repeated heat cycles, corrosion, and long-term engine use. During an engine rebuild, old hardware may show wear, corrosion, damaged threads, or surface deterioration. Replacing the complete set helps provide consistent hardware condition throughout the cylinder head assembly.
When to Replace This Set
• Cylinder heads are being removed or refitted
• Engine rebuild or top-end overhaul is being carried out
• Existing nuts or washers are corroded or damaged
• Threads are worn or compromised
• Cylinder head studs are being replaced or serviced
• Engine restoration is in progress
• Correct replacement hardware is required for reassembly.
Where it fits on the car
This set fits within the engine cylinder head assembly, securing the cylinder heads to the engine studs.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903108302
The product you are viewing cross references to these numbers
Product Information
Cylinder head nuts and washers (set of 48 parts)This OE Match kit is a complete cylinder head fixing set consisting of 24 washers and 24 nuts. It is designed for use during cylinder head assembly, engine rebuilding, or restoration where the listed part numbers are specified.
Sold as a complete 48-piece set containing 24 washers and 24 cylinder head nuts
Fits:
Porsche 911 1965 - 1977
Porsche 930 Turbo 1975 - 1977
Porsche 914-6
Diagram ref no 17
The cylinder head nuts and washers secure the cylinder heads correctly to the engine studs. The washers help distribute clamping load beneath the nuts, while the nuts provide the required fastening force to hold the cylinder heads securely in position.
Functions:
• Replaces cylinder head nuts and washers
• Complete 48-piece set
• Includes 24 cylinder head washers
• Includes 24 cylinder head nuts
• Helps distribute cylinder head clamping load correctly
• Supports secure cylinder head installation
• Suitable for engine rebuilding and restoration
Why Replace This Set?
Cylinder head nuts and washers are subjected to high clamping loads, repeated heat cycles, corrosion, and long-term engine use. During an engine rebuild, old hardware may show wear, corrosion, damaged threads, or surface deterioration. Replacing the complete set helps provide consistent hardware condition throughout the cylinder head assembly.
When to Replace This Set
• Cylinder heads are being removed or refitted
• Engine rebuild or top-end overhaul is being carried out
• Existing nuts or washers are corroded or damaged
• Threads are worn or compromised
• Cylinder head studs are being replaced or serviced
• Engine restoration is in progress
• Correct replacement hardware is required for reassembly.
Where it fits on the car
This set fits within the engine cylinder head assembly, securing the cylinder heads to the engine studs.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903108302
99903108302
99903108301
90110438203
The product you are viewing cross references to these numbers
About kit
This kit is comprised of the following items:
24 x Washer for cylinder head nut. Porsche 911 65-77 / 914-6 (99903108302/1)
Unit Price: £2.00
Due In 12 Days
24 x Cylinder head nut. Porsche 911 1965-89 / 356 / 912 (90110438204/1)
Unit Price: £2.35
In Stock - 24 Hour Dispatch
Vehicle Group
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 1975-1977 3.0L Turbo (930)
- Porsche 914 (1970-1976)
Price: £104.40
Available: 1 of 2 items (50%)
>> Check Stock
99903109101K/KIT
Product Information
A complete fastening set of 24 cylinder head nuts and 24 head nut washers used to clamp the cylinder heads and cylinder barrels to the crankcase on classic air-cooled Porsche engines. This kit contains head nuts and "Large style washers"; used for 3.0 SC, 3.2 & 3.3 Turbo engines
Includes:
24 x 90110438204/1 - OE Match Cylinder head nuts
24 x 99903109101/1 - OE Match Head nut washers
Fits:
Porsche 911 1978 - 1989
Diagram ref no 16 and 17
This OE Match kit combines the correct-style M10 cylinder head nuts (OE ref no 90110438202) with the corresponding large head nut washers (OE ref no 99903109101). Together, they provide the correct bearing surface and clamping load distribution required during engine assembly or top-end rebuilds, helping maintain sealing integrity under heat cycling and high operating loads.
Head nuts and washers can suffer from corrosion, rounding, surface wear, and reduced load consistency after multiple rebuilds. Replacing them with OE-match hardware supports accurate torque application and helps maintain long-term clamp load stability - critical for top-end durability.
When to replace:
• During any top-end rebuild or head/cylinder removal
• Nuts show corrosion, damaged hex, or thread wear
• Washers are grooved, distorted, or heat-marked
• You suspect prior incorrect torqueing or hardware reuse history
• Preventive replacement on engines with unknown rebuild history
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903109101K
The product you are viewing cross references to these numbers
Product Information
Cylinder head nut & washer kit.A complete fastening set of 24 cylinder head nuts and 24 head nut washers used to clamp the cylinder heads and cylinder barrels to the crankcase on classic air-cooled Porsche engines. This kit contains head nuts and "Large style washers"; used for 3.0 SC, 3.2 & 3.3 Turbo engines
Includes:
24 x 90110438204/1 - OE Match Cylinder head nuts
24 x 99903109101/1 - OE Match Head nut washers
Fits:
Porsche 911 1978 - 1989
Diagram ref no 16 and 17
This OE Match kit combines the correct-style M10 cylinder head nuts (OE ref no 90110438202) with the corresponding large head nut washers (OE ref no 99903109101). Together, they provide the correct bearing surface and clamping load distribution required during engine assembly or top-end rebuilds, helping maintain sealing integrity under heat cycling and high operating loads.
Head nuts and washers can suffer from corrosion, rounding, surface wear, and reduced load consistency after multiple rebuilds. Replacing them with OE-match hardware supports accurate torque application and helps maintain long-term clamp load stability - critical for top-end durability.
When to replace:
• During any top-end rebuild or head/cylinder removal
• Nuts show corrosion, damaged hex, or thread wear
• Washers are grooved, distorted, or heat-marked
• You suspect prior incorrect torqueing or hardware reuse history
• Preventive replacement on engines with unknown rebuild history
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903109101K
99903109101
90110438202
99903109101
90110438203
The product you are viewing cross references to these numbers
About kit
This kit is comprised of the following items:
24 x Cylinder head nut. Porsche 911 1965-89 / 356 / 912 (90110438204/1)
Unit Price: £2.35
In Stock - 24 Hour Dispatch
24 x Head nut washer. Porsche 911 1978-89 (99903109101/1)
Unit Price: £2.95
In Stock - 24 Hour Dispatch
Vehicle Group
Vehicle Group
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1978-1989 3.3L Turbo (930)
Price: £127.20
In Stock - 24 Hour Dispatch
Call us
We're happy to help!
Monday-Friday: 8.30am - 5.30pm (GMT)
Saturday: Closed
Sunday: Closed
Customer Care
Information