1. Home
  2. Carburetors
  3. Tillotson
  4. HL-Series
  5. HL-Other
  6. Tillotson 363-503 Nozzle Check Valve
Tillotson 363-503 Nozzle Check Valve
363-503 Tillotson Nozzle Check Valve
Write a Review

Tillotson 363-503 Nozzle Check Valve

Part Number: 363-503
Online Price: $9.76
Tillotson 363-503 Press-In Nozzle Check Valve for HL-Series Carburetors
Availability: In Stock.

Send to:

*We'll ask for shipping info at checkout

Description

Tillotson 363-503 OEM Nozzle Check Valve – Press-In Style for HL-Series Carburetors


The Tillotson 363-503 Nozzle Check Valve is a genuine OEM replacement part designed to safeguard your HL-series carburetor from internal damage in the event of a backfire. It features a built-in check ball that seals the fuel passage, protecting the internal circuits from reverse pressure.


While the shape and length of the nozzle may influence signal strength and overall carb tuning, the check ball itself is not a tuning component. Its purpose is strictly protective.


Key Features:

  • OEM Part Number: 363-503
  • Design: Press-in style nozzle
  • Material: Durable brass construction
  • Function: Prevents damage from backfire with internal check ball
  • Exact Dimensions:
    • Length: 0.352 inches
    • Diameter: 0.250 inches


Important Installation Notes:

  • This is a press-in nozzle, not threaded. Ensure your carburetor uses a press-in style before removal or installation.
  • Do not attempt to press-fit into threaded carburetors.
  • Remove the high-speed adjustment screw before installation or removal to avoid damaging the needle.
  • When installing, align the side hole of the nozzle with the pick-off hole (fuel circuit hole connected to the adjustment screw). Misalignment can lead to poor performance or tuning issues.


Troubleshooting Tip:

If you're experiencing fuel leakage from the high side at idle, the check valve is not the cause. This condition is usually due to a worn needle valve or leaking seat.


Compatible Tillotson HL Carburetor Models:

  • HL-232B
  • HL-282B
  • HL-304A / HL-304E
  • HL-309A / HL-309E
  • HL-310A / HL-311A
  • HL-317A / HL-317E
  • HL-318A / HL-321A / HL-321E
  • HL-334A / HL-334AA / HL-334AB / HL-334B
  • HL-339A
  • HL-384A / HL-384B
  • HL-385A

Always verify your carburetor model or measure the nozzle dimensions to ensure a proper fit before ordering.

FAQ

Q1: What is the purpose of the Tillotson 363-503 nozzle check valve?

A: The 363-503 nozzle check valve protects your Tillotson HL-series carburetor from backfire damage. It includes an internal check ball that seals off the fuel passage during reverse pressure events.


Q2: Is this nozzle press-in or threaded?

A: This is a press-in style nozzle. It should not be used in carburetors designed for threaded nozzles.


Q3: Will this part help fix fuel leaking from the high-speed side at idle?

A: No. Fuel leakage at idle is usually caused by a worn needle valve or leaking seat, not by the check valve.


Q4: What are the installation precautions?

A:

  • Always remove the high-speed screw before installation.
  • Ensure correct alignment between the nozzle’s side hole and the pick-off hole inside the carburetor.
  • Do not force a press-in nozzle into a threaded carb.


Q5: How do I confirm this fits my carburetor?

A: Check your Tillotson HL carburetor model number or measure your existing nozzle (Length: 0.352", Diameter: 0.250") to ensure a proper match.


Q6: Which Tillotson carburetors are compatible with the 363-503?

A: It fits a wide range of HL-series models, including HL-232B, HL-304A, HL-334A, HL-384B, and many others. Always double-check compatibility before purchase.

Related Items

Recently Viewed Items

Logo