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Tillotson Captured Forked Inlet Control Lever/Fulcrum Arm
155A-27 Tillotson Inlet Control Lever/Fulcrum Arm (Captured)
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Tillotson Captured Forked Inlet Control Lever/Fulcrum Arm

Part Number: 155A-27
Online Price: $2.29
155A-27 OEM Tillotson Captured Forked Inlet Control Lever / Fulcrum Arm
Availability: In Stock.

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Description

155A-27 Tillotson OEM Captured Forked Inlet Control Lever (Fulcrum Arm)


Precision Fuel Control Component for HL, HR, HW, HX, and HM Carburetors

The 155A-27 Tillotson Captured Inlet Control Lever—commonly known as a Fulcrum Arm—is a critical fuel metering component in Tillotson carburetors. It lifts the inlet needle, allowing fuel to flow into the high and low-speed circuits, directly impacting fuel delivery, engine response, and carburetor tuning.


This is a captured-style fulcrum arm, meaning its forked end securely holds the needle valve dowel—unlike uncaptured versions that do not lock the needle. Captured designs are commonly used in carburetors with the fuel pump stack facing downward for better control under vibration or racing conditions.


Fulcrum Arm Height Details:

Proper fulcrum arm height is essential for correct fuel flow. Too high or too low can cause rich or lean conditions.

  • Factory Height Spec: 0.085"
  • Recommended Settings:
    • Gas Carburetors: 0.075" (Use EC 705 Gauge)
    • Methanol (Alky) Carburetors: 0.065" (Use EC 704 Gauge)


Key Features:

  • OEM Part #: 155A-27
  • Captured forked design secures needle valve for reliable operation
  • Compatible with most HL, HR, HW, HX, HB, HC, HM-series carburetors
  • Suitable for gasoline and methanol fuel setups
  • Critical component for tuning fuel delivery
  • Precision-machined for consistent performance


Applications & Fitment:

Compatible with a wide range of Tillotson carburetor models, including but not limited to:

HL-Series: HL-1A, HL-129E, HL-132H, HL-166B&C, HL-189F, HL-227A, HL-229A, HL-321E, HL-250A–E, HL-274E, HL-292G, HL-293A,F, HL-299E, HL-304E, HL-304WX, WXA, WXG, HL-306A, HL-314E–G, HL-324A, HL-334A–AB, HL-339A, HL-341A, HL-342A, HL-348A–E, HL-352A, HL-355A–E, HL-357A–B, HL-360A–C, HL-365A–B, HL-366A, HL-368A, HL-371A, HL-374A, HL-380A–B, HL-383A, HL-384A–B, HL-385A, HL-388A, HL-395A
HR-Series: HR-181B, HR-184A, HR-190A, HR-191C/G, HR-196A
HW-Series: HW-10A–B, HW-11A–B, HW-12A, HW-17A, HW-19A, HW-22A, HW-23A, HW-27A, HW-30A–35A, HW-43A
HX-Series: HX-10A, HX-12A
HB, HC, HM-Series: HB-10A–12A, HC-103A, HC-112A, HM-1A, HM-2A, HM-12A
…and many more.


Important Installation Notes:

  • Always verify needle style compatibility (captured vs. uncaptured)
  • Use a proper fulcrum gauge tool to set accurate height
  • Incorrect height may result in fuel starvation or flooding
  • Consider replacing during routine rebuilds or tuning sessions

FAQ

Q1: What function does the 155A-27 fulcrum arm perform?
A: It holds the inlet needle in place and lifts it to allow fuel flow into the carburetor’s high- and low-speed circuits. The height of this arm directly affects fuel metering, idle behavior, and throttle response.


Q2: What is a “captured” fulcrum arm?
A: A captured fulcrum arm has a forked end that wraps around or captures the needle valve dowel. This helps keep the needle secured and reduces movement under vibration—important in performance or racing applications.


Q3: What are the typical fulcrum arm height settings?
A:

  • Factory spec is usually 0.085"
  • For gas carburetors we often use 0.075" (with EC-705 gauge)
  • For methanol (alky) carburetors it’s usually 0.065" (with EC-704 gauge)


Q4: Which Tillotson carburetor models does this arm fit?
A: It fits a wide range of Tillotson HL, HR, HW, HX, HM, HB, HC series carburetors (see full model list in product info). It is not suitable for models that require an uncaptured fulcrum arm.


Q5: What happens if the fulcrum arm height is set incorrectly?
A: If too high — flooding or rich mixture; if too low — lean condition, hesitation, or fuel starvation. Tuning the arm height correctly is crucial for optimal performance.


Q6: When should I replace the fulcrum arm?
A: Replace it during a carburetor rebuild if you notice wear, corrosion, or if it doesn’t hold the needle securely. Also consider replacement if switching fuel types (gas ? methanol) or after heavy use.

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