Type H SU carburettor overview
The Type H SU carburettor overview.
The Type H carburettor is the earliest of the four Type H (Horizontal) types fitted as standard to many vehicles such as performance sports cars with a multiple installation to more normal saloon types from early 1950s on .
Note that all later types are largely just refined and updated versions and they all use the same basic elements of a SU carb.
Made of a die-cast aluminium body in which vertically mounted suction chamber and piston assembly is mounted with a jet assembly with the suction chamber below it, and a float chamber assembly attached by an arm to the body.The body has bolts to mount the unit to the engine and for the attachment of an air cleaner system or the intake system depending on the use.
Inside the underside of the body unit has an internally threaded boss for attachment of the linked jet assembly, and float chamber arm. Other cast features on the body include bosses bored to form throttle spindle bearings, a lug with a hole to accept the tail of a jet return (tension) spring. a housing for a piston lifting pin, tapped holes for vacuum connections, and bosses for throttle/choke interconnecting linkage bearings.The suction chamber is a die-cast aluminium cylinder with a central guide tube fitted with a hardened steel sleeve bearing. The guide tube is extended at the top of the chamber and internally threaded for attachment of a hydraulic damper. Lugs are provided at the chamber base for attachment to the unit body with screws.
A piston slides in the bearing in the suction chamber, the smaller, lower diameter protruding into the bore of the carburettor body. The piston consists of two parts; the hollow piston rod and the piston disc with integral suction disc. The piston has two ports drilled from the top and emerging on the downstream side of the piston.The jet assembly slides in upper and lower bearing. The maximum height of the jet is determined by the jet adjusting nut The jet size is identified by a code number stamped on the steel fork face.
