This is the "BIG ONE", when the extra large 4 1/4 in. cap is removed, the opening measures a generous 3-5/8 in. for fast filling.
Your fabricator will appreciate the stepped shoulder at the base of the bung,
it serves as a positioning locator.
This feature holds the bung in place while welding in a hole of a
flat surface, or in the end of tubing when constructing a filler neck extension. This grouping of cap assemblies includes a weld-able aluminum bung.
The step ahead.
The lightweight, non-vented cap features positive grip finger notches that are easy to get a hold of, and don't hurt your hand. Prime 6061-T6 billet aluminum is precision CNC machined into a lightweight, attractively designed cap; featuring quick-start coarse threads. Each is supplied standard with a Buna O-ring; positive sealing and "radially squeezed " to hold the cap secure. Check out the entire line up, Billet Aluminum Fill Caps is a Pro-werks specialty.
Great caps. Great colors.
To compliment the color coordination of your project, the caps are finished off in Pro-Werks Brilliance anodized colors in your choice of black, red, blue, silver, or beautifully Micro-polished aluminum.
The right size matters.
Easy Turn Fill Caps come in many sizes and are packaged as complete
assemblies with your choice of one of the many versatile mounting options, or each component is also available separately.
Be sure to check out the entire line up - Billet aluminum Easy Turn Fill
Caps are a Pro-werks specialty. Watch the Video below to learn more !
Proudly made
here in the USA.
Note: Welding should always be performed by a qualified welder.
Finish Your Tank
We also offer a full line of weld-in plumbing bungs to complete your tank project.
Click the images below to view all the options.
Q:
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How much do I need to tighten a fill cap?
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A:
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It is not necessary to bottom the fill cap into the bung−just
adequately seat the O-ring. The radial squeeze action on the O-ring creates a positive seal and helps prevent the cap from coming loose. |
Q:
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What should I use to lubricate the Buna O-ring?
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A:
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Applied periodically, a light coating of Dielectric grease has proven to work well as an O-ring lubricant.
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Q:
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Is Buna rubber compatible with my fluid?
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A:
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Buna is a synthetic rubber compound suitable for use with most fluids. Buna components may need to be replaced by a material compatible with the specific chemistry of some fluids. |
Q:
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How do I properly weld my bung?
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A:
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Apply several small, equally spaced tacks and preheat before welding. Keep the weld small to minimize potential distortion or shrinkage.
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Q:
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If my threads are tight after welding, how do I fix it?
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A:
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The solution is simple. Apply a small amount of fine grit lapping compound to the threads then turn the cap back and forth in the bung until the desired fit is achieved. Be patient−do not force the process. Thoroughly clean both sets of threads before use. |
Inside Grip Diameter:
4.25 in.
Outside Grip Diameter:
4.75 in.
Thickness:
0.35 in.
Thickness:
0.89 in.
Thread:
3-3/4-18 Thread
Outised Diameter:
4.375 in.
Thread:
3-3/4-8
Height:
0.875 in.
Diameter:
4.125 in.