O-Ring Sets

O-Ring Sets: the small seals that keep fuel, oil and coolant where they belong

An o-ring is a simple rubber or elastomer ring that seats in a groove and squeezes to form a leak-tight seal between two mating parts. In practice, most of the o-ring sets on this page do one of a few jobs: sealing fuel injectors into a rail or head, sealing an oil cooler or its lines, or sealing AN thread fittings on a plumbing system. When you pull an injector, swap a cooler, or build up an AN system, you replace the o-rings as a set because reusing a stretched or nicked seal is how a fresh install turns into a weep or a leak. Buying the matched set means every seal in the assembly goes back in new.

What ThreePiece stocks

There are 56 o-ring sets in this category, from 15 brands. The range runs from $17 to $3,342 for what is currently in stock – that spread reflects everything from a small injector seal pack up to a large injector-specific set. Vibrant carries the most listings here at 19, followed by Injector Dynamics with 10, then TwinPower, Cometic Gasket and S&S Cycle. Radium Engineering, ARB, FAST, TiALSport, Turbosmart, Perrin Performance, Nitrous Express, HKS, Fragola and Victor Reinz round out the list.

Concrete examples give you the shape of the range. The Vibrant AN Thread O-Rings Box Set covers AN -3 through -16 in one box for plumbing work. The Perrin oil cooler o-ring kit seals Subaru oil cooler setups, the MAHLE Original injector o-ring kit fits the Ford E-350 Club Wagon, the Cometic inner primary to case o-ring is a Harley EVO 10-pack, and the ARB o-ring set serves CKMA/P compressors.

How to choose

Match the set to the job first. An AN box set is only useful if you are building fittings; an injector kit is sized to a specific injector and vehicle. Where a listing shows fitment – 9 products here carry fitment data – the covered makes are Harley-Davidson, Ford and Subaru, across model years from 1948 to 2017, on vehicles like the Harley-Davidson Big Twin, Ford E-350 Club Wagon and Subaru WRX. The rest are application-general seals sized by dimension or thread. Buy the matched set rather than a single ring when you are opening more than one joint – the cost of a full set is small next to a second teardown.

What else you need with it

O-rings rarely go in alone. If you are pulling injectors, look at fuel pumps. Plumbing work pairs with fittings and adapters. Sealing jobs on the block often call for gasket kits or head gaskets, and cooling work ties into radiators. Browse the full engine components section for related parts.

Fitment and ordering

Not sure which set matches your build? Call fitment help at 813-535-5801 or reach us through contact us. All orders ship free, and Affirm and Katapult financing is available.

O-Ring Sets: the small seals that keep fuel, oil and coolant where they belong

An o-ring is a simple rubber or elastomer ring that seats in a groove and squeezes to form a leak-tight seal between two mating parts. In practice, most of the o-ring sets on this page do one of a few jobs: sealing fuel injectors into a rail or head, sealing an oil cooler or its lines, or sealing AN thread fittings on a plumbing system. When you pull an injector, swap a cooler, or build up an AN system, you replace the o-rings as a set because reusing a stretched or nicked seal is how a fresh install turns into a weep or a leak. Buying the matched set means every seal in the assembly goes back in new.

What ThreePiece stocks

There are 56 o-ring sets in this category, from 15 brands. The range runs from $17 to $3,342 for what is currently in stock – that spread reflects everything from a small injector seal pack up to a large injector-specific set. Vibrant carries the most listings here at 19, followed by Injector Dynamics with 10, then TwinPower, Cometic Gasket and S&S Cycle. Radium Engineering, ARB, FAST, TiALSport, Turbosmart, Perrin Performance, Nitrous Express, HKS, Fragola and Victor Reinz round out the list.

Concrete examples give you the shape of the range. The Vibrant AN Thread O-Rings Box Set covers AN -3 through -16 in one box for plumbing work. The Perrin oil cooler o-ring kit seals Subaru oil cooler setups, the MAHLE Original injector o-ring kit fits the Ford E-350 Club Wagon, the Cometic inner primary to case o-ring is a Harley EVO 10-pack, and the ARB o-ring set serves CKMA/P compressors.

How to choose

Match the set to the job first. An AN box set is only useful if you are building fittings; an injector kit is sized to a specific injector and vehicle. Where a listing shows fitment – 9 products here carry fitment data – the covered makes are Harley-Davidson, Ford and Subaru, across model years from 1948 to 2017, on vehicles like the Harley-Davidson Big Twin, Ford E-350 Club Wagon and Subaru WRX. The rest are application-general seals sized by dimension or thread. Buy the matched set rather than a single ring when you are opening more than one joint – the cost of a full set is small next to a second teardown.

What else you need with it

O-rings rarely go in alone. If you are pulling injectors, look at fuel pumps. Plumbing work pairs with fittings and adapters. Sealing jobs on the block often call for gasket kits or head gaskets, and cooling work ties into radiators. Browse the full engine components section for related parts.

Fitment and ordering

Not sure which set matches your build? Call fitment help at 813-535-5801 or reach us through contact us. All orders ship free, and Affirm and Katapult financing is available.