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EC Tillotson Gas Fulcrum Arm Gauge
705 EC Tillotson Gas Fulcrum Arm Gauge
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EC Tillotson Gas Fulcrum Arm Gauge

Part Number: 705-G
Online Price: $10.00
Gauge Fulcrum Arm EC Gas
Availability: In Stock.

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Description

EC Tillotson Fulcrum Arm Gauge – Gas | 705-G Carburetor Tuning Tool


Accurately set fulcrum arm height in your Tillotson gas carburetor with EC’s 705-G Fulcrum Arm Gauge—an essential tool for racers, builders, and tuners who demand consistent, high-performance fuel delivery.


Made from precision-machined billet aluminum, this tool allows you to measure the height of the fulcrum arm in relation to the carburetor’s gasket surface—an often-overlooked but critical factor in carburetor performance and tuning.


Key Features:

  • Designed for Tillotson diaphragm carburetors (HL, HR, HW, etc)
  • Machined from durable billet aluminum for long-lasting precision
  • Two-sided gauge with measured settings:
    • .085” – Factory setting
    • .075” – EC Blueprinted Gas Carburetors
  • Measures from gasket surface to fulcrum arm
  • Ensures proper metering diaphragm function and prevents flooding


Why Fulcrum Arm Height Matters:

  • Dictates how much leverage the metering diaphragm has on the fuel inlet needle
  • Controls fuel flow to both high and low-speed circuits
  • Incorrect height can lead to:
    • Rich or lean fuel conditions
    • Carburetor flooding
    • Poor throttle response
  • May slightly affect pop-off pressure due to the change in spring installation height


When to Use It:

  • Every carburetor rebuild
  • Before race days or high-performance applications
  • Anytime fuel delivery becomes inconsistent


If the fulcrum arm sits too high, it may make contact with the metering diaphragm, keeping the needle valve open and causing the engine to flood. This gauge ensures you’re always within the correct specs to avoid costly mistakes and inconsistent tuning.


Don’t guess—measure. The EC 705-G Fulcrum Arm Gauge gives you precision control over one of the most critical adjustments in Tillotson carburetor tuning.

FAQ

What is the EC 705-G Fulcrum Arm Gauge used for?

It’s a precision tool used to measure and set the fulcrum arm height on Tillotson diaphragm carburetors running on gasoline. This is critical for proper fuel metering and preventing flooding.


What are the two settings on the gauge?

The 705-G features:

  • .085" – Factory setting
  • .075" – EC Blueprinted setting for high-performance gas carburetors


How does fulcrum arm height affect carb performance?

It affects how much the main metering diaphragm can open the fuel inlet needle, impacting fuel volume to both high and low-speed circuits. Incorrect height can lead to lean/rich conditions or flooding.


When should I check the fulcrum arm height?

You should check it:

  • During every rebuild
  • Before race events
  • If you're tuning or troubleshooting inconsistent fuel delivery


Is this tool compatible with methanol (alky) carbs?

No, this version (705-G) is calibrated for gasoline-fueled Tillotson carbs. EC offers a separate gauge for methanol applications.

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