# R5673-8 NGK Standard Racing Spark Plug | Genuine NGK Spark Plug

## 🔧 Product Description

**NGK Standard Racing Spark Plug – Part Number: R5673-8**

NGK racing spark plugs are built for sustained high-RPM, high-temperature competition use, with precious-metal electrodes and cold heat ranges chosen for heavily loaded engines. Racing plugs are application-specific – heat range selection is critical, so confirm the specification for your engine before fitting.

## ⚙️ Key Features

-   Competition-grade construction for sustained high RPM and cylinder temperatures
-   Cold heat range for heavily loaded engines
-   Pure alumina silicate ceramic insulator, providing superior strength and better heat transfer
-   Triple seals prevent leakage

## 📏 Specifications

-   NGK stock number: 3249
-   Thread: Racing Spark Plugs
-   Reach: .460"
-   Hex: 16 mm (5/8 in)
-   Seat: Tapered
-   Terminal: Solid
-   Type: 14mm Spark Plugs cont'd V-Power Non-Resistor

## 🚘 Application

Listed in NGK's application charts for marine, motorcycle, ATV and snowmobile equipment. The chart shows a 1.0 mm gap for these engines, but check it against your engine's manual before fitting.

-   Flagship TC500 (350 CID, HI PERFORMANCE, 1993-1975) – Inboard Engine
-   Flagship TC500 (454 CID, HI PERFORMANCE, 1993-1975) – Inboard Engine
-   Flagship TC650 (454 CID, HI PERFORMANCE, 1977-1975) – Inboard Engine
-   Mercruiser 270 (8 CYL GM SMALL BLOCK, TAPER SEAT) – Inboard Engine
-   Mercruiser 325 (8 CYL GM BIG BLOCK, FROM) – Inboard Engine
-   Mercruiser 350 (8 CYL GM BIG BLOCK) – Inboard Engine
-   Mercruiser 460 CYCLONE (8 CYL GM BIG BLOCK) – Inboard Engine
-   Mercruiser 475 TURBO (8 CYL GM BIG BLOCK) – Inboard Engine
-   Mercruiser HP500 (8 CYL GM BIG BLOCK, 540 CID) – Inboard Engine
-   Mercruiser HP525 SC (8 CYL GM BIG BLOCK) – Inboard Engine
-   Mercruiser HP575 (8 CYL GM BIG BLOCK) – Inboard Engine
-   Mercruiser HP575 SCI (8 CYL GM BIG BLOCK) – Inboard Engine
-   Mercruiser HP600 SC (8 CYL GM BIG BLOCK) – Inboard Engine
-   Mercruiser HP800 SC (8 CYL GM BIG BLOCK) – Inboard Engine

That is the 14 most common of 15 applications NGK's charts list for this plug – ask us to check yours.

## 🔄 Supersession & Cross Reference

NGK's cross-reference tables list this plug against these part numbers.

-   Autolite: 134, 3264, AR133, AR134
-   Champion: 263, BL3, V61
-   ACDelco: 438T
-   Accel: 263
-   Motorcraft: AF1

## 📦 Condition

-   Brand new genuine product
-   Supplied in original packaging

## Details

- **Price:** 19.0 AUD
- **Vendor:** NGK
- **Type:** Ignition & Controls

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 19.00 AUD | In stock |

## Images

- R5673-8 NGK racing spark plug
- R5673-8 NGK racing spark plug firing end

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/r5673-8-ngk-standard-racing-spark-plug-genuine-ngk-spark-plug)
> Updated: 2026-09-03