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EC 446INT 1.125 HL Spigot Intake Manifold
446INT 1.125" HL Spigot Intake Manifold
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EC 446INT 1.125 HL Spigot Intake Manifold

Part Number: 446INT
Online Price: $31.99
EC 446INT Billet Spigot Intake – 1.125" HL Carb to Spigot Port
Availability: In Stock.

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Description

EC 446INT Billet Spigot Intake Manifold – 1.125" Tillotson HL to Spigot Port


Adapt HL-Series Tillotson Carburetors to Custom Spigot-Style Intakes


The EC 446INT Billet Spigot Intake Manifold is a high-performance adapter designed to mount 1.125" bore Tillotson HL-series carburetors to engines equipped with a spigot-style intake manifold. Originally engineered for the Briggs & Stratton World Formula, it has become a go-to solution for racers and builders using custom intake setups with welded pipes or spigot manifolds on performance small engines.


Whether you're converting to a diaphragm-style carb for methanol use or running a custom welded intake, the 446INT bridges the gap—offering precise fitment, high flow potential, and universal adaptability.


Key Features:

  • Adapts Tillotson HL 1.125" carburetors to spigot-style intake manifolds
  • 1.125" throttle bore with 1.300" OD spigot to match most welded or slip-fit manifolds
  • Integrated pulse hole in flange for diaphragm pump operation (HL carb compatible only)
  • Ideal for custom heads with welded intakes or engines where bolt-on flanges restrict flow
  • Requires a compatible hose or boot to connect to your spigot port


Technical Specifications:

  • Throttle Bore: 1.125"
  • Spigot Outer Diameter: 1.300"
  • Pulse Port: Yes (matched to HL carb configuration only)
  • Material: CNC-machined billet aluminum
  • Fitment Note: Not compatible with HL carbs with 1.000" or 1.060" bores—pulse port will not align correctly.


Why Use the 446INT?

Most small engine cylinder heads—especially cast heads—have limited bolt spacing and cross-sectional area, which restricts airflow at high RPM. By welding a pipe or spigot directly to the head, you eliminate the need for a traditional bolt-on flange and gain increased port area. The 446INT allows you to mount a flange-style HL carburetor onto these high-flow, spigot-style manifolds, unlocking more power and better tuning potential.


Use Case Examples:

  • Methanol race engines using Tillotson HL-series carbs
  • Custom-built heads with welded intake pipes
  • Small engine builders adapting performance carbs to spigot-style manifolds
  • Karting and mini bike racing where high RPM fueling is critical


What You’ll Need:

  • A Tillotson HL carburetor with a 1.125" bore
  • A spigot intake port with a 1.300" OD fitment
  • A rubber coupler, boot, or hose that matches both the spigot and the intake manifold

EC 446INT vs. EC 447INT Spigot Intake Manifolds

Feature

EC 446INT

EC 447INT

Carburetor Compatibility

Tillotson HL (1.125" throttle bore only)

Tillotson HL (1.00" throttle bore only)

Incompatible With

HL carbs with 1.00" or 1.060" bore (pulse port misalignment)

HL carbs with 1.125" or 1.060" bore (pulse port misalignment)

Throttle Bore Diameter

1.125"

1.00"

Spigot Outer Diameter

1.300"

1.300"

Mount Style

Spigot (hose or rubber boot mount)

Spigot (hose or rubber boot mount)

Pulse Port

Yes – pre-machined in flange

Yes – pre-machined in flange

Installation Type

Hose/boot connection to spigot-style intake manifold

Hose/boot connection to spigot-style intake manifold

Use Case

High-performance methanol engines with welded intakes or spigot ports

Methanol racing engines using 1.00" HL carbs, World Formula setups

Original Application

Adapt 1.125" HL to spigot-style manifolds (e.g., custom heads)

Adapt 1.00" HL to Briggs World Formula spigot intakes

Material

CNC-machined billet aluminum

CNC-machined billet aluminum

FAQ

1. What carburetors does the EC 446INT support?

It supports Tillotson HL-series carburetors with a 1.125" throttle bore only. Smaller bore versions (1.000" or 1.060") will not align correctly with the built-in pulse port.


2. What is the spigot size on this intake?

The spigot outer diameter is 1.300", which fits most common rubber boots or couplers used in spigot-style intake manifolds.


3. Is it compatible with stock cylinder heads?

Not directly. This intake is primarily intended for custom builds using welded spigot manifolds or World Formula heads with spigot-style intake ports. For bolt-on applications, check out other EC flange-style intakes.


4. Does it include a pulse port for diaphragm carbs?

Yes, it has a pre-machined pulse hole in the flange for proper operation of diaphragm-style Tillotson HL carburetors.


5. What else do I need to install this?

You’ll need a compatible hose or rubber boot to connect the spigot to your intake manifold. Ensure the boot matches both the 1.300" OD spigot and your intake port diameter.


6. Why use a spigot instead of a flange intake?

Flange mounts can restrict airflow due to bolt spacing and gasket limitations. A spigot-style connection eliminates these restrictions, offering increased flow, better port shaping, and cleaner packaging—ideal for high-performance methanol engines.

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