Sierra 18-5484-1 Electronic Distributor (Late HEI), Replaces 3857449, Conventional Rotation V8 262-454 & 502

The Sierra 18-5484-1 Electronic Distributor is a Late HEI style ignition distributor engineered as a plug-in replacement for GM-style EST ignition system distributors used in marine V8 engine applications. It is built for conventional rotation V8/LH 262-454 & 502 engines, except 348/409 and tall block engines. At the core of the distributor is the Ignitor II ignition module with adaptive dwell control, which adjusts spark timing across the entire RPM range to help maximize engine performance and maintain consistent, reliable ignition output.

Internally, the distributor uses an upper roller bearing paired with an oil impregnated bronze sintered bottom bushing, aligned and bored for accuracy to deliver maximum durability under marine operating conditions. A machined, heat treated gear is manufactured to tight tolerances to ensure long-term durability and consistent timing. The steel gear is compatible with both flat tappet and hydraulic roller cams, giving it broad application across GM-based marine V8 setups. The housing is of aluminum construction, and the distributor combines a ball bearing and bushing setup for maximum timing stability and long service life.

The unit features a reliable, high signal strength trigger system and is built to meet or exceed SAE J1171 standards, the marine ignition protection standard. A companion Sierra 18-5281 tune-up kit is available for maintenance of this distributor. As with other Sierra ignition components, this distributor is engineered to meet the demands of high horsepower marine engines while standing up to the harsh marine environment, and it meets or exceeds the performance of the original equipment part it replaces.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-5484-1
• Product Type: Electronic Distributor (Late HEI)
• Rotation: Conventional Rotation
• Fitment: V8/LH 262-454 & 502 (Except 348/409 and Tall Block Engines)
• Ignition Module: Ignitor II with adaptive dwell control
• Bearing Type: Upper roller bearing and oil impregnated bronze sintered bottom bushing
• Gear Material: Machined, heat treated gear
• Gear Compatibility: Flat tappet or hydraulic roller cams
• Housing Material: Aluminum
• Standard Compliance: Meets or exceeds SAE J1171
• Compatible Tune-Up Kit: Sierra 18-5281
• Weight: 2.99 pounds
• Product Dimensions: 0.39 x 0.39 x 0.39 inches

Fitment

• Conventional Rotation V8/LH 262-454 & 502 (Except 348/409 and Tall Block Engines)

Replaces (OEM)

• 3857449

Frequently Asked Questions

What engines does the Sierra 18-5484-1 distributor fit? The Sierra 18-5484-1 Electronic Distributor is designed for conventional rotation V8/LH 262-454 & 502 engines, except 348/409 and tall block engines.

Does the 18-5484-1 replace an OEM distributor? Yes, the 18-5484-1 replaces OEM number 3857449 and is designed as a plug-in replacement for the GM-style EST ignition system distributor.

What ignition module is used in this distributor? The Sierra 18-5484-1 uses the Ignitor II ignition module with adaptive dwell control, which adjusts spark timing across the entire RPM range to maximize performance.

What is the housing material on the 18-5484-1 distributor? The housing is constructed of aluminum, paired with a ball bearing and bushing combination for maximum timing stability and long service life.

Is the gear on the 18-5484-1 compatible with roller cams? The steel gear on the Sierra 18-5484-1 distributor is compatible with either flat tappet or hydraulic roller cams.

How much does the Sierra 18-5484-1 distributor weigh? The Sierra 18-5484-1 Electronic Distributor weighs 2.99 pounds.

What bearing setup does this distributor use for durability? An upper roller bearing and an oil impregnated bronze sintered bottom bushing are installed and aligned bored for accuracy, providing maximum durability in the 18-5484-1 distributor.

Does the 18-5484-1 distributor meet marine ignition standards? Yes, the Sierra 18-5484-1 distributor meets or exceeds SAE J1171 standards for marine ignition protection.

Is there a tune-up kit available for the 18-5484-1 distributor? Sierra offers tune-up kit 18-5281 as a companion part for servicing the 18-5484-1 Electronic Distributor.

How does the 18-5484-1 compare to the original equipment distributor it replaces? The Sierra 18-5484-1 is engineered to meet or exceed the performance of the original equipment distributor it replaces, in this case OEM number 3857449.

What kind of trigger system does the 18-5484-1 use? The Sierra 18-5484-1 distributor features a reliable, high signal strength trigger system as part of its Late HEI design.

What are the dimensions of the Sierra 18-5484-1 distributor? The Sierra 18-5484-1 Electronic Distributor measures 0.39 x 0.39 x 0.39 inches.