Name: -16AN & -20AN Water Neck Adapters
Brand: Autoplump
SKU: AP1250-16BLK
Price: 69.95 USD
Availability: InStock
Rating: 4.88 (74 reviews)

Real-World Results From Our Customers

No studio lighting. Just real installs from real AutoPlumb customers.

No Welding

Forget welding aluminum bungs. No TIG, no distortion, no cleanup - just a simple connection

No Clamps

No more bulky clamps. A tighter, safer, cleaner connection every time.

No Splices

Cuts out unnecessary junctions that leak, weaken, or restrict flow. One solid hose, no interruptions.

No Reducers

Eliminates reducers when your radiator and water pump outlets don’t match.

How to Convert Your Cooling System to AN

STEP 1:

MEASURE YOUR RADIATOR / PUMP'S O.D.

Use calipers or a micrometer

Measure BEHIND the raised bead

NOTE: If your size is not listed on our website, a radiator water neck can be reduced in size approximately .040" and most water pumps can be reduced in size .050" or more. A file and emery cloth works well to reduce the size, but the method is up to you. Reduce it between the bead and radiator/pump. Adapters can also be installed on water necks that are up to .015" under the listed size.

STEP 2:

DOWNLOAD AND PRINT THE ADAPTER TEMPLATES

Find the adapter template for your measurement here

Transfer the templates to poster board for a stiffer template.

DO NOT use the templates to determine the O.D size to order.

STEP 3:

DOWNLOAD AND PRINT THE THERMOSTAT HOUSING TEMPLATES

Find the thermostat housing template for your brand here

Print a straight, 45°, or 90° depending on which is best for your application.

NOTE: Any angle hose end can be connected directly to a straight thermostat housing if that better suits your application. AutoPlumb AN Adapters can be used on your stock thermostat housing if we do not have a housing for your brand.

STEP 4:

DOWNLOAD AND PRINT THE HOSE END TEMPLATES

Find the hose end templates here

Start by printing which angles you think will work, then proceed to Step 5.

STEP 5:

DETERMINE YOUR HOSE END ANGLES

Mix and match the various angles until you get the ends to align.

Take your time on this step, it is crucial for assembly.

While the hose does bend (refer to the hose radius template), do not rely on the hose to make a bend for you.

STEP 6:

MEASURE YOUR HOSE LENGTH

Measure the distance between the hose end templates.

This measurement is an estimation, always give yourself extra hose in case of errors or if a bend is needed.

Taping the templates and/or having assistance makes this step easier.

STEP 1:

MEASURE YOUR RADIATOR / PUMP'S O.D.

Use calipers or a micrometer

Measure BEHIND the raised bead

NOTE: If your size is not listed on our website, a radiator water neck can be reduced in size approximately .040" and most water pumps can be reduced in size .050" or more. A file and emery cloth works well to reduce the size, but the method is up to you. Reduce it between the bead and radiator/pump.

STEP 2:

DOWNLOAD AND PRINT THE ADAPTER TEMPLATES

Find the adapter template for your measurement here

Transfer the templates to poster board for a stiffer template.

DO NOT use the templates to determine the O.D size to order.

STEP 3:

DOWNLOAD AND PRINT THE THERMOSTAT HOUSING TEMPLATES

Find the thermostat housing template for your brand here

Print a straight, 45°, or 90° depending on which is best for your application.

NOTE: Any angle hose end can be connected directly to a straight thermostat housing if that better suits your application. AutoPlumb AN Adapters can be used on your stock thermostat housing if we do not have a housing for your brand.

NOTE: Any angle hose end can be connected directly to a straight thermostat housing if that better suits your application. AutoPlumb AN Water Neck Adapters can be used on your stock thermostat housing if we do not have a housing for your brand.

STEP 4:

DOWNLOAD AND PRINT THE HOSE END TEMPLATES

Find the hose end templates here

Start by printing which angles you think will work, then proceed to Step 5.

STEP 5:

DETERMINE YOUR HOSE END ANGLES

Mix and match the various angles until you get the ends to align.

Take your time on this step, it is crucial for assembly.

While the hose does bend (refer to the hose radius template), do not rely on the hose to make a bend for you.

STEP 6:

MEASURE YOUR HOSE LENGTH

Measure the distance between the hose end templates.

This measurement is an estimation, always give yourself extra hose in case of errors or if a bend is needed.

Taping the templates and/or having assistance makes this step easier.

FAQs

Will the AutoPlumb Water Neck Adapter leak?

No, when measured and installed correctly the adapter will not leak. Unlike hose clamps that loosen over time, this design seals from the inside and once it's installled, you don’t have to touch it again.

What if my water pump and radiator outlet are different sizes?

No problem. Just accurately measure the O.D of each water neck, pick your AN size, and choose the adapter that fits.

Will this work on an LS?

Yes, it works perfectly. However, when space is limited you might have to get creative. Check out our common configurations page to see how other customers have installed theirs. Don't forget, the templates are your friend, they will help you mock your system before you have the parts in your hand.

How do I decide between -16AN & -20AN

Both -16AN or -20AN hose will provide enough flow for cooling given you have adequate air flow along with a properly sized water pump, radiator, fans, and shroud. Available space, appearance, and cost are the determining factors. Use the mock up templates to determine which size best fits your application. -20AN is most preferred for full size street machines based on looks. -16AN is well suited for drag cars, imports, and smaller engine vehicles.

Can this handle high-temperature coolant?

Absolutely. All components are rated for continuous coolant temps and under-hood heat. No swelling, softening, or clamp re-tightening needed.

Is it reusable?

Yes, you can remove and reinstall it without damaging the hose or fittings.

Amazing products

Great service as always very pleased with the product.I've used a lot of their products always pleased

Thank you for your kind words and continuous support! We are thrilled to hear that you are satisfied with our '-20AN Water-neck Adapters'. Your satisfaction is our top priority and we will continue to provide great products and service.

Thank you again for your review and adding the awsome photos! Fantastic!
Joe

Absolutely beautiful

I put this on my c3 to replace an aging oem one and it is the jewel of the engine. Easy install. Tool about 1 hr.

Thank you for your kind words and for choosing our -20AN Water-neck Adapter! We are so glad to hear that it was easy to install and that it has become the jewel of your engine. Thank you for your support and we hope it continues to serve you well. Thank you for posting photos of your build...very nice!!

Happy driving!
Joe

Extremely Satisfied

I knew I wanted the AutoPlumb system on my build when I started. The process was simple, and the results are phenomenal.

Thank you for your positive feedback! We are glad to hear that our -20AN Water-neck Adapters met your expectations and made the AutoPlumb system an easy choice for your build. We appreciate your support and hope you continue to enjoy the phenomenal results. Thank you for adding photos!! Great work!

Happy driving!

Joe

Doesn't get any better than this!

I was looking for a nice radiator hose setup for my Chevelle. I was hesitant at first and purchased a few other designs. I regret ever thinking anything else on the market even came close. This is by far the best hose kit ever made! Just follow the instructions and you will love the results.

Thank you for your kind words and for choosing our -20AN Water-neck Adapters! We are thrilled to hear that our product exceeded your expectations and that you found it to be the best hose kit ever made. We strive to provide high-quality and easy-to-use products for our customers. We appreciate your support and hope to continue serving you in the future.

Happy driving with your Chevelle and thank you for adding the photos!!
Joe

Amazing Experience - '69 Chevelle

Super happy with the results, from the ordering to final installation. Ordered the wrong color first, and the return was simple and headache free. Innovative design and sexy looks. Totally recommend for anyone's vehicle.

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-16AN & -20AN Water Neck Adapters

-16AN & -20AN Water Neck Adapters

AP1250-16BLK

Real-World Results From Our Customers

How to Convert Your Cooling System to AN

How to Convert Your Cooling System to AN

STEP 1:

MEASURE YOUR RADIATOR / PUMP'S O.D.

STEP 2:

DOWNLOAD AND PRINT THE ADAPTER TEMPLATES

STEP 3:

DOWNLOAD AND PRINT THE THERMOSTAT HOUSING TEMPLATES

STEP 4:

DOWNLOAD AND PRINT THE HOSE END TEMPLATES

STEP 5:

DETERMINE YOUR HOSE END ANGLES

STEP 6:

MEASURE YOUR HOSE LENGTH

STEP 1:

MEASURE YOUR RADIATOR / PUMP'S O.D.

STEP 2:

DOWNLOAD AND PRINT THE ADAPTER TEMPLATES

STEP 3:

DOWNLOAD AND PRINT THE THERMOSTAT HOUSING TEMPLATES

STEP 4:

DOWNLOAD AND PRINT THE HOSE END TEMPLATES

STEP 5:

DETERMINE YOUR HOSE END ANGLES

STEP 6:

MEASURE YOUR HOSE LENGTH

FAQs

Customer Reviews