GM EFI Quick-Connect to AN — The Adapter Cheat Sheet (LS/EFI Swaps)
AN Hose 101 • Hot Rod AN
Quick answer (sizes): Most GM EFI feeds are 3/8" and returns are 5/16". Adapt 3/8" → AN-6 for typical builds (step to AN-8 on high-HP feeds). Adapt 5/16" → AN-6 for returns.
Quick answer (filter/regulator): Our Corvette-style filter/regulator has built-in AN-6 male fittings—no quick-connect adapters needed. If you’re using an OEM or an aftermarket unit without AN ports, use quick-connect adapters as shown below.
Adapter advantage: Our GM quick-connect → AN adapters use a threaded lock-nut that physically clamps the connection—so they can’t “pop off” like a failed plastic clip. The nut’s clearance cutout also lets you lock onto short-tube, tight-access sockets.
- Why GM quick-connects matter
- Identify your connector (3/8" vs 5/16")
- Adapter mapping (quick-connect → AN)
- Common layouts (with diagrams)
- Install steps (click, lock-nut, tug test)
- Troubleshooting: leaks & misfits
- Parts & recommended products
- FAQ (click to expand)
Why GM quick-connects matter
GM’s spring-retained quick-connect fittings appear on tank modules, frame lines, filter/regulators, and rails. Adapting them to AN hose makes swaps clean and serviceable. Use our threaded-lock adapters where the factory port is quick-connect; use our Corvette-style filter/regulator with built-in AN-6 when you want to skip adapters entirely.
Identify your connector (3/8" vs 5/16")
- Measure the tube OD: ~9.5 mm = 3/8" (feed), ~8.0 mm = 5/16" (return). Use a caliper.
- Don’t trust color clips: Not universal. Size it, don’t guess.
- Filter/reg bodies: Our unit uses AN-6 male ports (no adapters). OEM-style units typically have 3/8" in/out and 5/16" return quick-connects.
Adapter mapping (quick-connect → AN)
| Factory port | Use this connection | Typical AN line | Notes |
|---|---|---|---|
| 3/8" GM quick-connect (feed) | Our 3/8" QC → AN-6 adapter with threaded lock-nut | AN-6 PTFE hose & ends (AN-8 for high HP) | Lock-nut + cutout handles short/close-clearance sockets |
| 5/16" GM quick-connect (return) | Our 5/16" QC → AN-6 adapter with threaded lock-nut | AN-6 PTFE hose & ends | Plenty of capacity for returns |
| OEM/aftermarket filter/regulator (no AN ports) | Adapters: 3/8" IN, 3/8" OUT, 5/16" RETURN → AN | AN-6 feed/return typical | Mount rear; short return loop to tank |
| Hot Rod AN filter/regulator (our unit) | Built-in AN-6 male ports (no adapters) | AN-6 feed forward; AN-6 short return | Mount near tank; run single feed to rails |
Common layouts (with diagrams)
Return-style EFI with GM quick-connects (OEM-style ports)
Returnless with Hot Rod AN filter/regulator (AN-6 male ports)
Install steps (click, lock-nut, tug test)
- Depressurize: Pull the pump fuse/relay and run the engine down, or bleed at a service port. Work cool and clean.
- Lightly oil the O-rings: A tiny film of clean oil on the adapter’s small internal O-rings prevents damage during insertion and helps a smooth seat.
- Seat the quick-connect end: Push the adapter straight into the GM socket until it clicks and bottoms. Verify the inner retainer has engaged.
- Engage the threaded lock-nut: Rotate the adapter’s lock-nut forward. Use the cutout in the nut to capture the factory tube’s lip (where the plastic clip would normally latch). Thread the nut down snug to clamp the connection.
- Tug test: Pull back firmly—no movement. The lock-nut mechanically retains the adapter, so it can’t pop off like a failed plastic clip.
- Plumb the AN side: Use PTFE AN hose and ends. Keep the fine filter after the pump (≤10 μm for EFI; ~40 μm or finer for carb).
- Pressure check: Prime the system and inspect for seepage. Fix now, not later.
Troubleshooting: leaks & misfits
| Issue | Likely cause | Fix |
|---|---|---|
| Drip at quick-connect | Wrong size (3/8 vs 5/16), dry or nicked O-ring, lock-nut not seated | Measure; oil O-rings; re-seat; tighten lock-nut; tug test |
| Won’t connect | Debris in socket; misaligned retainer; no oil on O-rings | Clean socket; align retainer; oil O-rings; seat until click |
| Lean at WOT | Feed undersized; post-filter restrictive; long run | Step to AN-8 feed; larger ≤10 μm element; verify pump wiring |
Parts & recommended products
- GM Quick-Connect to AN Adapters — threaded lock-nut design with clearance cutout (3/8" and 5/16" to AN-6/AN-8).
- Hot Rod AN Filter/Regulator (~58 psi) — built-in AN-6 male ports; mount near tank for a single-feed layout.
- EFI & Carb Fuel Filters — ≤10 μm post-pump (EFI); ~40 μm post-pump (carb).
- PTFE Hose & Fittings Bundles — nylon-jacketed (nylon → stainless braid → PTFE core) or stainless braided (stainless braid → PTFE core).
- PTFE Hose End Fittings — straights and angles for clean routing.
FAQ (click to expand)
Is 3/8" the same as AN-6?
Not the same, but they pair well. 3/8" describes the factory tube OD; AN-6 is the hose/fitting size (37° flare). Use a 3/8" GM quick-connect adapter that ends in AN-6 to bridge the two.
Do I need adapters with your filter/regulator?
No. Our filter/regulator has built-in AN-6 male ports. If you’re using an OEM or aftermarket unit with quick-connects, then use our adapters.
What makes your adapters more secure?
A threaded lock-nut mechanically clamps the adapter to the GM socket, so it cannot pop off like a failed plastic clip. The nut’s cutout captures the tube lip, solving short/close-clearance connections.
Should I lube the O-rings?
Yes—add a thin film of clean oil to the adapter’s small internal O-rings before installation. It protects the O-rings and helps a smooth, damage-free seat.
Where should the filter go?
EFI: fine filter after the pump (≤10 μm). Carb: ~40 μm after the pump (or finer if the element is large enough). With our filter/regulator, mount near the tank and run one feed forward.
Scope notes: Exclude AN-4 (not stocked). Hose shown here is for fuel/low-side fluids, not brakes or power steering.
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