Complete Guide to AN Cooling Systems

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Everything You Need to Know About Converting Your Cooling System to AN Fittings

If you've spent any time around custom hot rods, muscle cars, race cars, or LS swaps, you've probably noticed more builders replacing traditional rubber radiator hoses with braided AN hose and aluminum fittings.

At AutoPlumb, helping enthusiasts build cleaner, more reliable plumbing systems is what we do every day. One of the most common questions we receive is how to convert a traditional cooling system to AN fittings and which components are needed to do it correctly.

Whether you're building your first project or upgrading an existing combination, this guide explains what an AN cooling system is, why builders make the switch, the parts involved, and how to plan a successful conversion.

What Is an AN Cooling System?

An AN cooling system replaces traditional rubber radiator hoses and hose clamps with braided hose and reusable AN fittings. Unlike a conventional cooling system, which relies on rubber hoses secured by clamps, AN fittings create a mechanical seal on a precision-machined 37-degree flare.

At AutoPlumb, we've seen more builders make the switch because AN plumbing offers a cleaner appearance, greater routing flexibility, and a professional finish that complements the rest of a performance engine bay.

No Welding Required

Years ago, converting a cooling system to AN fittings meant welding aluminum bungs onto thermostat housings, radiators, or modifying factory components.

One of the reasons AutoPlumb developed the Water Neck Adapter was to eliminate that extra fabrication. Our adapters attach directly to the water neck and convert it to AN without welding, hose clamps, splices, or reducers, making AN cooling system conversions more accessible for builders of every skill level.

Water Neck Adapters

The water neck adapter converts the engine's coolant outlet to an AN connection. AutoPlumb Water Neck Adapters are designed specifically to simplify this conversion while maintaining a clean, professional appearance.

Features include:
CNC-machined billet aluminum construction
No welding required
Available in both -16AN and -20AN configurations

AN Thermostat Housings

A thermostat housing connects the engine's thermostat to your AN cooling hose while maintaining proper coolant flow.

AutoPlumb AN Thermostat Housings are engineered to complement our Water Neck Adapters, giving builders compatible components that work together as part of a complete AN cooling system.

Planning Your Conversion

One of the biggest mistakes we see builders make is ordering parts before planning the entire cooling system.
Before purchasing components, we recommend determining:

Engine Platform

Radiator inlet and outlet sizes

Water neck location

Desired hose routing

AN hose size

Hose-end angles

Clearance around accessories

To make planning easier, AutoPlumb also offers printable mock-up templates that allow you to verify fitment before ordering hose ends, extensions, and adapters.

Common Mistakes to Avoid

Many first-time builders encounter the same issues during an AN cooling system conversion.
Avoid these common mistakes:

Skipping mock-ups before ordering parts. Our printable templates are designed to help eliminate this problem before you spend money on components.

Ordering the wrong hose size

Selecting incorrect hose-end angles

Measuring before final component installation

Mixing incompatible fitting styles

Frequently Asked Questions

Which hose size should I use?

-16AN is well suited for drag cars, imports, and smaller engine vehicles.
-20AN is most preferred for full size street machines based on looks.

Why Choose AutoPlumb?

At AutoPlumb, we specialize in high-performance automotive plumbing.
Our goal is simple: make AN plumbing easier to understand, easier to install, and more accessible for enthusiasts building everything from weekend cruisers to race cars. Whether you're converting a single radiator hose or building an entirely new cooling system, our products are designed to help you achieve a clean, reliable, leak-free installation.

We offer a complete selection of cooling system components, including:

Water Neck Adapters

AN Thermostat Housings

Braided Hose

AN Hose Ends

Other AN Adapters

Final Thoughts

Converting your cooling system to AN fittings is about more than appearance. It provides greater flexibility, cleaner plumbing, and a more professional finish that complements the rest of a performance build.

At AutoPlumb, we've built our product line around making these conversions as straightforward as possible. From Water Neck Adapters and Thermostat Housings to hose ends, braided hose, and planning templates, our goal is to help builders spend less time troubleshooting and more time enjoying their projects.

Whether you're working on an LS swap, classic muscle car, hot rod, or race car, careful planning and quality components can make all the difference.