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Made in the USA

Pro-werks Easy Turn Filler Cap with O-Ring

Sale price $69.99 USD
Part # C74-784-LB
Select Fill Cap Size
Then Select Fill Cap Color
Four knurled aluminum fuel fill caps shown side by side in silver, black, red and blue finishes

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Specifications

1-5/8 Inch Fill Cap

1-1/4-12 Straight Thread
Cap Weight: 1.06 oz.
Without Lanyard Boss
Includes O-Ring
(Cap Replacement O-Ring is C73-749)

2 Inch Fill Cap

1-1/2-12 Straight Thread
Cap Weight: 1.62 oz.
Without Lanyard Boss
Includes O-Ring
(Cap Replacement O-Ring is C73-769)

2-3/4 Inch Fill Cap

2-1/4-10 Straight Thread
Cap Weight: 3.32 oz.
With Lanyard Boss, Accepts Lanyard Chain Kit
Includes O-Ring
(Cap Replacement O-Ring is C73-788-A)

4-1/4 Inch Fill Cap

3-3/4-8 Straight Thread
Cap Weight: 7.86 oz.
With Lanyard Boss, Accepts Lanyard Chain Kit
Includes O-Ring
(Cap Replacement O-Ring is C74-788-A)

Overview

The lightweight, non-vented cap features positive grip finger notches that are easy to get a hold of. Prime 6061-T6 billet aluminum is precision CNC machined into a lightweight, attractively designed cap; featuring quick-start coarse threads. Each screw on Cap is fitted with a Buna O-ring; positive sealing and "radially squeezed" to hold the cap secure. Backed by The Chassis Shop's Satisfaction Guarantee.

Watch Product Videos ⏵

Fill Cap with O-Ring

This design uses a radial squeeze action on a Buna O-ring for a secure seal. Precision machined quick-start coarse threads make using these caps a breeze.
The large selection of Pro-werks’ mounting bungs are crafted from Steel, Aluminum or Stainless Steel and available in both weld and bolt-on styles.


Great Filler 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, or beautifully Micro-Polished aluminum – the Pro-werks Jewelry Quality finishes are unmatched and impeccable!

Four machined aluminum fuel cell caps with scalloped grip edges, shown in polished silver, black, red and blue finishes


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

Set of four black anodized fuel fill caps with scalloped grip edges, shown in graduated sizes on a white background

Popular Uses:

  • Custom-fabricated tanks
  • Fuel cells
  • Rear End housings
  • Valve covers
  • Overflow tanks
  • Ice boxes for intercoolers
  • Ballast tanks
  • Inspection viewing ports



Proudly Made in the USA

Both the cap and bung are precision CNC machined light weight billet aluminum, right here in the USA.

Be sure to check out the entire line up - Billet aluminum Easy Turn Fill Caps are a Pro-werks specialty.

You can always count on Pro-Werks to do it right!

Red anodized cap with lobed grip flange, black O-ring seal and "Made in the USA" engraving, held in a hand for scale


Customer Comments:

"I use your bolt on caps and bungs on my carbon fiber Cummins common rail valve covers. Love the quality. Thank you."
– Randy Davis, Owner of OldSkoolFab, Inc.


"I upgraded my fuel cell to an Easy Turn fill cap assembly. It wasn't long until all my friends did the same. Great product!"
– As shared with us at the PRI Show


Frequently Asked Questions

Q: How much do I need to tighten a fill cap?
A: 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: What should I use to lubricate the Buna O-ring?
A: Applied periodically, a light coating of Dielectric grease has proven to work well as an O-ring lubricant.

Q: Is Buna rubber compatible with my fluid?
A: Buna is a synthetic rubber compound suitable for use with many fluids. Buna components may need to be replaced by a material compatible with the specific chemistry of some fluids.

Marketing banner showing a stack of Pro-Werks fill cap brochures with blue, red, silver and black finger-notch caps, beside text inviting readers to view it

Product Videos

Two anodized fuel fill caps, one red and one blue, held in a hand, top view showing scalloped grip edges and a printed logo Video still of a presenter behind a table displaying aluminum and plastic fuel cells with a row of colored filler caps Blue anodized aluminum fuel fill cap with lobed grip, installed on a welded sheet aluminum tank sitting on a fixture table Round aluminum filler cap shown as a weld in bung welded into a flat aluminum plate, held in gloved hands, with TIG weld beads visible Aluminum canister and green-topped grip tool on a drilled fixture plate, beside a blue anodized cap marked Made in the USA, a flat file and pliers
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