Ancient and Modern: Strip and Rebuild of the Tillotson HL Carburettor

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Strip and Rebuild of the Tillotson HL Carburettor.

For the purposes of this article, we will assume that you have a Tillotson HL type carburettor that requires a full strip and rebuild.
Before starting work on the carburettor, you will need the following parts and tools to hand :

1 x Full Rebuild Kit. (Tillotson Part Number RK-102HL)
De-greasing agent, for cleaning external parts.
Clean, lint-free wipers.
1 x Aerosol can of Carburettor Cleaner.
A long, thin walled, 5/16”Hex socket.
Screwdriver to suit the retaining screws.
Access to a small compressed air supply.

Before work begins, ensure you have a clean, dust free surface to work on and proceed as follows:

1. Clean the exterior surfaces using a stiff paint brush and de-greasing agent.
2. Remove the Strainer Cover Retaining Screw and the Plastic Top Cover.
3. Remove the Cork Strainer Gasket and the Mesh Strainer Screen.
4. Remove the Six Screws and the Fuel Pump Body.
5. Remove the Fuel Pump Diaphragm and Gasket.
6. Remove the Main Diaphragm Cover plate.
7. Remove the Main Diaphragm and its Gasket.
8. Remove the Inlet Control Lever Screw, which will release the Fulcrum Pin and Tension Spring.
9. Remove the Inlet Needle from the Inlet Seat.
10. Using the thin wall socket, carefully remove the Inlet Seat and its Washer from the Body Casting.
11. Remove the High and Low Adjustment Screws.

Carefully clean each individual part using the Aerosol Carb. Cleaner, and blow dry with compressed air.
Make sure that you can spray carb.cleaner through the Fuel Passage ways in the carb. body.
Blow dry the carb. Body with compressed air.

Re-Assembly.

Re-assembly is a straightforward process, but the following hints may be usefull:

New Gaskets are always fitted first, with its associated diaphragm on top of it.
Be carefull that the Diaphragms, Gaskets and Cover Casting are carefully fitted over the small, cast pins.
Make sure that the Inlet Control Lever is Flush with the Metering Chamber Floor, when the assembly is fully installed.
It may be necessary to slightly bend the forked tab of the inlet Control Lever to achieve the above.
Check that the Inlet Control Spring locates over the dimple on the Inlet Control Lever.
Don’t forget to fit the small washer below the Inlet Seat and don’t over tighten the Inlet Seat into the Metering Chamber Casting.
Evenly tighten the fuel pump body retaining screws to ensure a complete seal of the compressed components.
Re-fit the High and Low adjustment screws, taking care to fit them in the correct location.

There is a lot more to say on the subject of Carburettor Testing and Tuning, but the above information will enable you to replace the component parts and be fairly confident that the thing will work when you next come to use it !

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