---
product_id: 517784676
title: "Improved Racing GM Gen III & IV LS Billet Rear Passage Plug Oil Diverter Barbell"
brand: "improved racing"
price: "¥26772"
currency: JPY
in_stock: true
url: https://www.desertcart.jp/products/517784676-improved-racing-gm-gen-iii-and-iv-ls-billet-rear
store_origin: JP
region: Japan
---

# Threaded M4x0.7 removal hole CNC-machined 6061-T6 aluminum Double Viton O-ring seal Improved Racing GM Gen III & IV LS Billet Rear Passage Plug Oil Diverter Barbell

**Brand:** improved racing
**Price:** ¥26772
**Availability:** ✅ In Stock

## Summary

> 🛠️ Upgrade your LS engine’s lifeline—because clean oil means peak power.

## Quick Answers

- **What is this?** Improved Racing GM Gen III & IV LS Billet Rear Passage Plug Oil Diverter Barbell by improved racing
- **How much does it cost?** ¥26772 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.jp](https://www.desertcart.jp/products/517784676-improved-racing-gm-gen-iii-and-iv-ls-billet-rear)

## Best For

- improved racing enthusiasts

## Why This Product

- Trusted improved racing brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Made in the USA:** Crafted domestically with premium materials for unmatched durability and reliability.
- • **Direct OEM Upgrade:** Seamlessly replaces plastic GM LS Gen III & IV barbell plugs for instant performance boost.
- • **Effortless Maintenance:** Threaded M4x0.7 hole allows quick, tool-friendly removal—no more wrestling with stuck plugs.
- • **Leak-Proof Double Seal:** Dual Viton O-rings guarantee zero dirty oil bypass, protecting your engine’s heart.
- • **Precision Engineered Flow:** CNC-machined billet aluminum ensures optimal oil passage with minimal restriction.

## Overview

The Improved Racing Billet Rear Passage Plug is a precision CNC-machined 6061-T6 aluminum replacement for GM LS Gen III & IV plastic barbell plugs. Featuring a double Viton O-ring seal and a threaded removal hole, it eliminates dirty oil bypass, improves oil flow, and simplifies maintenance—all proudly made in the USA.

## Description

Improved Racing designed this billet aluminum rear galley plug (commonly known as the "barbell") for Gen III and IV GM LS series engines to improve oil flow and completely eliminate dirty engine oil from bypassing the filter. This part is recommended for replacing the plastic OEM plug in any engine build. Improved Racing's barbell features a second O-ring that completely seals off the dirty oil from the clean oil, forcing 100% of oil flow through the filter. Sharp corners were avoided and machined as smooth fillets to improve oil flow, while the bullnose tip helps smooth oil flow to the oil filter. The shaft diameter is smaller than the OEM plastic barbell to minimize flow restriction. A threaded hole was added so that the barbell can be easily removed with any M4x0.7 screw.

## Features

- Improves oil flow and completely eliminates dirty engine oil from bypassing the filter
- Double O-ring design seal positively seals the oil gallery passage
- Direct replacement for plastic OEM barbell plug on GM LS Gen III & IV engines
- Precision CNC-machined from billet 6061-T6 aluminum with Viton O-rings
- Threaded M4x0.7 hole allows for easy removal from engine block
- Made in the USA.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| Manufacturer | speedway motors |
| Brand | Improved Racing |
| Package Dimensions | 12.3 x 9.7 x 1.3 cm; 27 g |
| Item model number | EGM-501 |
| Manufacturer Part Number | EGM-501 |
| OEM Part Number | 12573460 |
| Material | 6061-T6 Aluminum, Viton O-rings |
| Assembly Required | No |
| Manufacturer | speedway motors |
| Item Weight | 27 g |

## Product Details

- **Brand:** Improved Racing
- **Manufacturer:** speedway motors

## Images

![Improved Racing GM Gen III & IV LS Billet Rear Passage Plug Oil Diverter Barbell - Image 1](https://m.media-amazon.com/images/I/41uS83nyh3L.jpg)
![Improved Racing GM Gen III & IV LS Billet Rear Passage Plug Oil Diverter Barbell - Image 2](https://m.media-amazon.com/images/I/41brjkmu6zL.jpg)
![Improved Racing GM Gen III & IV LS Billet Rear Passage Plug Oil Diverter Barbell - Image 3](https://m.media-amazon.com/images/I/41fip3soVzL.jpg)
![Improved Racing GM Gen III & IV LS Billet Rear Passage Plug Oil Diverter Barbell - Image 4](https://m.media-amazon.com/images/I/41-qhbBcRAL.jpg)
![Improved Racing GM Gen III & IV LS Billet Rear Passage Plug Oil Diverter Barbell - Image 5](https://m.media-amazon.com/images/I/51rdX4ZSJoL.jpg)

## Questions & Answers

**Q: do u need to replace the o-ring in the future?**
A: The O rings would only require replacement if it was removed after the initial installation. If you were removing during engine replacement or rebuilding, we would recommend replacement at that time.

**Q: Will this fit a 2008 gmc Savana 3500 6.0L?**
A: As long as it’s your standard LS block. Be at a 5.3, 5.7, 6.0, 6.2, or even a 7.0 Liter you are good to go. I bought this for my newly built 408 stroker 6 liter iron block and it is far superior to the stock style. I also like that it has a threaded portion in the back to be able to easily take it out if you ever need to, plus it’s double O-ringed.

**Q: Why is this one different than all the others? The barbell is longer on one end.**
A: Take a look at the last photo in the listing, where you can see the barbell installed in the engine. You can see it's designed so the tip fills the entire closed section of the passage. The barbell is only narrow where oil needs to flow around it. This helps create a better seal at the tip and also makes the barbell stronger.

**Q: 2008 chevy silverado 5.3 this will work on my engine**
A: Yes, this will fit all Gen III and IV LS and Vortec family blocks, so it will fit your 5.3

## Frequently Bought Together

- Improved Racing GM Gen III & IV LS Billet Rear Passage Plug Oil Diverter Barbell
- Dorman 635-518 Engine Rear Main Seal Cover Compatible with Select Models
- Camshaft Retainer Plate Gasket Compatible with LS Series Engines, &Bolt Kit ARP 134-1003 Gen III IV V for GM LS1 LS2 LS3 4.8 5.3L 6.0L 6.2L Vortec Corvette Cam

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**Shop now:** [https://www.desertcart.jp/products/517784676-improved-racing-gm-gen-iii-and-iv-ls-billet-rear](https://www.desertcart.jp/products/517784676-improved-racing-gm-gen-iii-and-iv-ls-billet-rear)

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*Product available on Desertcart Japan*
*Store origin: JP*
*Last updated: 2026-02-17*