6 Bolt Fuel Cell Bung with 2-3/4 Inch Fill Cap
2-1/4-10 Straight Thread
3/4 in. Bung Height
6 on 4.438 in. Dia. Bolt Circle
Fits 2-3/4 in. Easy Turn Fill Cap

12 Bolt Fuel Cell Bung with 4-1/4 Inch Fill Cap
3-3/4-8 Straight Thread
7/8 in. Bung Height
12 on 5.343 in. Dia. Bolt Circle
Fits 4-1/4 in. Easy Turn Fill Cap

Bolt-on Fuel Cell Bungs

Pro-werks Fuel Cell type Filler Cap Bungs are available separately without the cap. These bolt-on style aluminum bungs come in two sizes, and do not require welding. Select anodized colors are available and include mounting hardware - so you won't need to run all over town looking for it!

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 finishes are impeccable!

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.

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!

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.