PTFE & AN Fittings

Q: Do I need PTFE tape to seal AN fittings on a PTFE fuel line?

No. PTFE AN fittings seal through a 37° flare and metal-to-metal contact on straight threads, not through tape. PTFE tape is designed for tapered NPT threads; wrapped around a straight AN flare it can sit in the seal path or shred into the fuel stream instead of stopping a leak. If your setup includes a tapered NPT adapter, wrap the tape 6 to 12 times in the tightening direction and add a thin layer of pipe dope before and after it, then leave tape off every AN-to-AN flare connection entirely.

Looking for a way to stop fuel line leaks for good? Evil Energy's PTFE AN fittings pair a PTFE hose core with precision-machined PTFE hose fittings so the seal holds under real engine heat, ethanol blends, and constant vibration, not just on the test bench. Every fitting in this collection is machined from 6061-T6 aluminum with a black anodized finish and a true 37° flare, tested to hold up to 1500 PSI of working pressure, with 360° swivel ends for stress-free routing on tight EFI, turbo, and LS swap builds.

Why PTFE AN Fittings Seal Better Than Rubber Hose Ends

PTFE doesn't behave like rubber once it's under a clamp. It compresses and stays compressed, so a standard barb or clamp fitting can't grip it the way it grips a rubber line. That's exactly why these AN hose ends rely on a 37° flare and metal-to-metal fit on straight threads instead of tape or thread sealant, which is built for tapered NPT threads and does nothing for a straight AN connection. Pair that with correctly torqued fittings and a quick flush of the line before install to clear manufacturing debris, and you get a mechanical seal that doesn't depend on the hose bouncing back to stay tight. For flare angles, torque reference, and a full walkthrough of common fuel system leaks and how to fix them, check our sealing guide.

PTFE Hose Fittings Built for High Heat and Ethanol-Blended Fuel

Daily-driven E85 builds and turbocharged setups put fittings through heat cycling and aggressive fuel chemistry that generic hardware often can't handle. The PTFE core in this lineup is rated from -76°F to 446°F (-60°C to 230°C) and is compatible with gasoline, diesel, and E85, while the fitting bodies carry an operating range of -65°F to 252°F, so the connection isn't the weak link in your fuel system. Use the size reference below to match your fitting to your build, or step up to a complete PTFE fuel line kit if you're building the whole line from scratch.

AN Size	Common Application
3AN to 4AN	Vacuum reference lines, oil and fuel pressure sending lines
6AN	Standard EFI fuel supply and return lines for most street builds
8AN	High-flow EFI, E85 conversions, larger turbo and supercharged setups
10AN to 12AN	High-horsepower, twin-turbo builds, and fuel cell plumbing

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FAQs about PTFE & AN Fittings

Do I need PTFE tape to seal AN fittings on a PTFE fuel line?

No. PTFE AN fittings seal through a 37° flare and metal-to-metal contact on straight threads, not through tape. PTFE tape is designed for tapered NPT threads; wrapped around a straight AN flare it can sit in the seal path or shred into the fuel stream instead of stopping a leak. If your setup includes a tapered NPT adapter, wrap the tape 6 to 12 times in the tightening direction and add a thin layer of pipe dope before and after it, then leave tape off every AN-to-AN flare connection entirely.

Why does a fitting on my PTFE hose leak even though it looks tight?

Most leaks trace back to one of four things: a fitting that isn't fully torqued, over-tightening that hairline-cracks the fitting, a mismatched thread type, or a burr on the flare face. Because PTFE hose fittings rely on a mechanical flare seal rather than the hose compressing back into shape, even a small gap at any of those points shows up as a leak. Before installing, flush the line to clear manufacturing debris and check both the hose end and the fitting face for burrs.

What temperature and fuel types can these PTFE AN fittings handle?

The PTFE hose core is rated from -76°F to 446°F (-60°C to 230°C), and the AN hose ends themselves carry an operating range of -65°F to 252°F, with compatibility across gasoline, diesel, and E85 or other ethanol blends. That range covers turbo heat soak and the more aggressive chemistry of ethanol-blended fuel, which is why PTFE is the standard choice for E85 conversions.

What AN size do I need for my fuel line?

As a starting point, 6AN covers most EFI street builds, 8AN suits higher-flow EFI setups and E85 conversions, and 10AN or 12AN is typically reserved for high-horsepower or twin-turbo applications, while 3AN and 4AN are common for vacuum or pressure-sensing lines rather than main fuel supply.

What should I actually look for in an AN fitting before trusting it on a fuel line?

Four things matter most: the body material and machining (6061-T6 aluminum with a true 37° flare, not a cast or undersized flare), a stated working pressure rating, confirmed compatibility with the fuel type you're running, and a straight-thread design that seals mechanically rather than depending on tape. Evil Energy's PTFE AN fittings meet all four, and correct installation, proper torque, clean threads, and a pre-install flush, matters just as much as the fitting itself for a fuel line that stays leak-free.

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PTFE & AN Fittings

Why PTFE AN Fittings Seal Better Than Rubber Hose Ends

PTFE Hose Fittings Built for High Heat and Ethanol-Blended Fuel

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