When There's No Off-the-Shelf Fuel Adapter
Catalogue ranges cover the popular platforms. The build that stalls is the one where the factory fuel rail is metric (say M12×1.5), the engine is a swap, or the platform is a cold JDM/Euro car nobody stocks an adapter for. You know which AN, NPT or metric size you need on the other end — there just isn't a part that bridges it.
EKINSUN machines that bridge. We make custom automotive fuel line and fuel rail thread adapters — AN to NPT to metric, in any combination — in billet 6061-T6 aluminium or 316 stainless, from a single piece to a small batch, quoted in 24 hours.
For high-pressure hydraulic or oil-line builds see hydraulic adapters; for general thread conversion see thread adapters; more automotive machining at automotive CNC parts.
Fuel Conversions We Machine
OEM rail → AN
Convert a factory quick-connect or metric fuel rail to a -6/-8 AN line for an engine swap.
Metric → AN / NPT
Adapt M12×1.5 and other metric fuel ports to AN or NPT for EFI and gauges.
EFI & turbo lines
High-pressure feed/return and turbo oil-feed adapters in strong billet alloy.
JDM / Euro platforms
Cold or older imports with no catalogue adapter — machined to your fitting.
From a sample
Send the old fitting and we reproduce a compatible adapter, no part number needed.
AN vs NPT — Getting the Seal Right
| Thread / type | How it seals |
|---|---|
| AN (37° flare) | Straight thread — seals on the 37° flare cone, not the threads; we machine a clean flare seat |
| NPT | Tapered thread — seals on the thread flanks (sealant aided) |
| Metric (M12×1.5 etc.) | Flat, cone or O-ring depending on the OEM port — matched to your fitting |
| ORB / O-ring boss | Seals on an O-ring in a machined boss, common on fuel rails and regulators |
AN and NPT are not interchangeable — one seals on a flare, the other on a taper — so we machine the correct seat on each end rather than forcing a mismatch that weeps fuel.
Build Your Adapter Spec — Instant RFQ
Configure your fuel adapter below. It generates clean RFQ text you can copy, or send straight to our engineers — no account, no CAD file.
Fuel Line Adapter Configurator
Define both ends, material and quantity. We reply with lead time and pricing within 24 hours.
Custom fuel adapter…
Materials for Fuel Adapters
Billet 6061-T6 aluminium
Light and strong for AN-style fuel adapters, with optional anodised finish for wear and looks.
6061 machining →316 stainless
For ethanol, methanol and corrosive fuels, and maximum durability under pressure.
316 machining →No Drawing? We Reverse Engineer It
Send the fitting or both ends
The factory rail fitting, the AN line, or the old adapter — even a worn sample.
We measure & draw it
Threads, flare seat and bore captured; we rebuild the CAD for free. How it works →
Confirm, then machine
You approve the drawing, then we turn and inspect it. Copy from a sample →
What to Send Us
- The factory fitting and the AN/NPT line, or the old adapter — or photos with one known dimension
- The thread on each end if you know it (e.g. M12×1.5 male to -6 AN male)
- Fuel type (petrol, diesel, ethanol/methanol) and system pressure
- Quantity — one to prove the fit, or a small batch — and delivery country
No CAD, no problem. Rebuilding the drawing is our job — free, confirmed with you before anything is cut. See how to order with no CAD file.
A note on branded parts. We make a compatible adapter to the form, fit and function you specify. We don't sell branded original products or imply affiliation with any original manufacturer — AN, NPT and brand names are used only to describe the thread or fitting standard.
Frequently Asked Questions
Yes — our core job. When a factory metric fuel rail (e.g. M12×1.5) has no catalogue AN adapter, send the thread or a sample and we machine a compatible adapter to convert it to the AN, NPT or metric size you need.
AN uses a straight thread that seals on a 37° flare cone; NPT is tapered and seals on the threads. They aren't interchangeable, so we machine the correct sealing feature on each end — a flare seat for AN, a clean taper for NPT — rather than forcing a leak-prone mismatch.
Yes. Off-the-shelf ranges cover popular platforms; cold or older JDM/Euro fuel fittings often have no adapter at all. Send the fitting or its thread and we machine a compatible one-off or small batch.
Billet 6061-T6 aluminium for light, strong AN-style adapters, with optional anodising; or 316 stainless for ethanol, corrosive fuels and durability. Chosen for pressure, fuel type and environment.
Yes. We manufacture a compatible adapter to the form, fit and function you specify. We don't sell branded originals or imply affiliation with any manufacturer; thread and fitting names describe the standard only.
Get a Fuel Adapter Quoted
The two ends, or a sample — that's all we need. Engineers reply in 24h.