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Tillotson 43-967 Brass Idle/High Mixture Screw
43-967 Tillotson Brass Idle/High Mixture Screw
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Tillotson 43-967 Brass Idle/High Mixture Screw

Part Number: 43-967
Online Price: $8.99
43-967 Tillotson Brass High/Low Mixture Screw – HL & HR Carburetor Tuning Screw
Availability: In Stock.

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Description

43-967 Tillotson Brass High/Low Mixture Screw – Fits HL & HR Carburetors


Optimize your engine's performance with the 43-967 Tillotson Brass High/Low Mixture Screw, a precision-engineered adjustment screw designed for select Tillotson HL and HR model carburetors. Commonly used as the high-speed mixture screw on methanol-fueled HL carburetors, this versatile component also functions as the low-speed or idle mixture screw on various HR carburetor models.


Key Features:

  • Dual Functionality: Acts as the high-speed screw on HL models and the low-speed (idle) mixture screw on HR models.
  • Performance Tuning: Enables precise fuel mixture adjustments for peak RPM and throttle response.
  • Durable Brass Construction: Manufactured from high-quality brass for enhanced durability and resistance to corrosion—perfect for harsh fuel environments like methanol.


Technical Overview:

  • The high-speed mixture screw controls fuel flow to the high-speed orifice/nozzle. It should be tuned for maximum engine RPM during wide-open throttle (WOT), especially in racing applications—typically adjusted on the longest straight of your track.
  • The low-speed (idle) screw regulates fuel entering the low-speed fuel well. Although often referred to as the "idle screw," it significantly influences low-end, midrange, and transition throttle performance—functioning as a crucial part of the main fuel circuit.


Special Notes for Methanol & 4-Cycle Engines:

Originally designed for 2-cycle engines, Tillotson carburetors can idle effectively. However, when used on 4-cycle engines with methanol, these carburetors may run excessively rich at idle, leading to hesitation or flat acceleration. Proper tuning of the low-speed screw—not just for idle but for transition and midrange—is essential to eliminate these performance issues.


Compatible Tillotson Carburetor Models:

  • HL-227E
  • HL-229A, HL-229E
  • HL-232E
  • HL-293A, HL-293F
  • HL-304E
  • HL-334A, HL-334B
  • HL-339A
  • HL-350A
  • HL-363C


Optimize Your Carburetor for Maximum Performance

Whether you're racing or tuning for performance, the 43-967 Tillotson High/Low Mixture Screw is an essential component for accurate fuel delivery and throttle response.

FAQ

What is the Tillotson 43-967 High/Low Mixture Screw used for?

The 43-967 Tillotson brass screw adjusts the fuel mixture in HL and HR model carburetors. It's used as a high-speed screw on some HL carburetors, especially those running methanol, and as a low-speed or idle screw on HR carburetors.


Which carburetor models is the 43-967 screw compatible with?

It fits the following Tillotson carburetor models: HL-227E, HL-229A/E, HL-232E, HL-293A/F, HL-304E, HL-334A/B, HL-339A, HL-350A, and HL-363C.


Is this mixture screw suitable for methanol-fueled engines?

Yes, the 43-967 screw is commonly used on methanol-fueled HL carburetors. It's ideal for tuning high-RPM racing engines where precise mixture control is critical.


Can I use the 43-967 mixture screw on 4-cycle engines?

Yes, but special tuning considerations apply. On 4-cycle engines, especially with methanol, the carburetor may run too rich at idle. Proper adjustment of the low-speed screw is essential to avoid hesitation or flat acceleration.


What material is the 43-967 mixture screw made from?

This adjustment screw is made from high-quality brass, offering durability, corrosion resistance, and compatibility with methanol fuel systems.

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