TILLOTSON HL Series User Manual

2
INTRODUCTION
The gasoline engine industry’s universal acceptance of Tillotson’s original diaphragm carburetor has
resulted in the development, by Tillotson engineers, of the “HL” Series carburetor.
Designed with a minimum of parts, this lightweight, compact carburetor includes an integral fuel pump
and filter in one small unit. The all position mounting feature allows a wide range of possible
applications.
Information contained in the following pages is presented as an aid to understanding construction,
operation and servicing of the “HL” series carburetor.
HL SCHEMATIC
1. Fuel Inlet
2. Fuel Pump Body
3. Fuel Pump Diaphragm
3A. Diaphragm Pump Inlet Valve
3B. Diaphragm Pump Outlet Valve
4 Fuel Pump Gasket
5 Diaphragm Cover Gasket
6 Metering Chamber
7 Idle Adjustment Screw
8 Impulse Channel
9 Idle Fuel Adjustment Orifice
10A. Primary Idle Discharge Port
10B. Secondary Idle Discharge Port
11. Throttle Shutter
12. Main Fuel Adjustment Orifice
13. Body
14. Venturi
15. Main Fuel Discharge Port
16. Choke Shutter
17. Fuel Inlet Supply Channel
18. Inlet Needle & Seat
18A. Copper Gasket
19. Main Adjustment Screw
20. Inlet Tension Spring
21. Inlet Control Lever
22. Fulcrum Pin
23. Atmospheric Vent Hole
24. Diaphragm Cover
25. Diaphragm
26. Atmospheric Chamber
27. Strainer Gasket
28. Fuel Inlet Screen
29. Strainer Cover Retaining Screw
30. Fuel Chamber
31. Pulse Chamber
32. Strainer
Cover
Note: On some models a one piece Idle Adjustment Screw (ref. 7) & Main
Adjustment Screw (ref. 19) with rubberized “O” ring attached (not illustrated
above) are used.

TILLOTSON HL Series Specifications

General

Type	Carburetor
Series	HL
Mounting Flange	2 bolt
Main Jet	Varies with model
Idle Jet	Varies with model