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Tillotson Uncaptured Inlet Control Lever/Fulcrum Arm
155A-23 Tillotson Inlet Control Lever/Fulcrum Arm (Uncaptured)
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Tillotson Uncaptured Inlet Control Lever/Fulcrum Arm

Part Number: 155A-23
Online Price: $1.99
155A-23 OEM Tillotson Uncaptured Inlet Control Lever / Fulcrum Arm
Availability: In Stock.

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Description

155A-23 Tillotson Uncaptured Inlet Control Lever / Fulcrum Arm (OEM)


The 155A-23 OEM Tillotson Inlet Control Lever, also known as the uncaptured fulcrum arm, plays a critical role in metering fuel flow in your carburetor. It lifts the inlet needle to allow fuel into the high- and low-speed circuits—making this a key tuning component for performance and reliability.


What Is “Uncaptured”?

Unlike the captured version, the uncaptured fulcrum arm simply rests on top of the inlet needle instead of securing it between forked tabs. This type is most commonly used on Tillotson carburetors with upright (top-mounted) fuel pump stacks, allowing easier service and more flexibility in certain setups.


Fulcrum Arm Height Settings

Proper fulcrum arm height is essential for consistent fuel delivery and performance:

  • Factory Setting: 0.085"
  • Gas Carburetors: 0.075" (Set using EC-705 Fulcrum Arm Gauge)
  • Methanol Carburetors: 0.065" (Set using EC-704 Fulcrum Arm Gauge)

Incorrect height can cause rich or lean fuel conditions, flooding, hard starts, or throttle hesitation.


Key Features:

  • OEM Tillotson part #155A-23
  • "Uncaptured" design – rests on top of the needle
  • Compatible with HL, HR, HW, HX, and other upright stack carburetors
  • Precision stamped for reliable fuel metering control
  • Essential for carburetor rebuilds or fuel type conversion


Fitment Notes:

This uncaptured inlet control lever is ideal for use in carburetor builds where the fuel pump stack is positioned upward(on top of the carburetor). Be sure to verify compatibility with your specific Tillotson model and setup.

If your carburetor has a downward-facing pump stack, we recommend using the captured fulcrum arm (e.g., part #155A-27) for better needle retention under vibration.

FAQ

Q1: What does the 155A-23 Fulcrum Arm do?
A: It lifts the fuel inlet needle to regulate the amount of fuel entering the carburetor’s fuel circuits. Its position directly affects tuning and engine response.


Q2: What’s the difference between captured and uncaptured fulcrum arms?
A: A captured arm secures the inlet needle’s dowel between its tabs. An uncaptured arm, like the 155A-23, simply rests on the needle tab. Uncaptured styles are used on top-mounted (upright) pump stacks.


Q3: How do I know if this fits my Tillotson carburetor?
A: Check whether your carburetor uses an upright pump stack and references this part number in its parts diagram. It's widely used across HL, HR, HW, HX models.


Q4: What fulcrum height should I use?
A:

  • Factory: 0.085"
  • Gas: 0.075" (EC-705 gauge)
  • Methanol: 0.065" (EC-704 gauge)
    Always measure with the correct gauge during tuning or rebuild.


Q5: Can I reuse a fulcrum arm?
A: Only if it shows no signs of wear, bending, or fuel contamination. For consistent performance, replacing it during a full rebuild is recommended.

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