Type 6 Carburettor 1929-54

Carburettor Problems

Poor starting and erratic tick over is usually caused by wear between the throttle valve and the body. Fitting a new slide in a worn body is like fitting a new chain to old sprockets, a waste of time. Wear is likely to be apparent as early as 5,000 miles, but can be rectified by boring the body oversize and fitting a sleeve to the slide. The materials used in this process will last a lot longer than the original. This is preferable to fitting a non-original later type of concentric carburettor. The new Monobloc carburettors that are now available have improved materials.  The prices for re-sleeving are found under RES169 or RES170 for a complete overhaul. Or replace the basics and seals with our overhaul pack here (monobloc only)

Type 6 Carburettor Settings Chart

A standard needle jet is used on the type 6 models unless a size is given. Standard needle jet on the Monobloc is .106. Standard needle jets are not usually marked. The needle position is the number of grooves from the top. Mixing chamber tops can have one, two or no threaded holes for cable adjusters; there is an adjuster on the carburettor OR in the cable, not both, see main listing for details.

In addition to the variation of carburettors listed above there is a profusion of float chambers. The arm that attaches the float chamber to the mixing chamber can be one of several angles in order to keep the float vertical and can be angled to the left or right dependant on which side it is attached. Also the fuel can be admitted at the top or the bottom and using alternative fittings; these are listed below in the column headed “Fuel pipe fitting”.

Top = top feed – Bott = Bottom feed
Direct = Fuel pipe is attached directly to a threaded brass fitting that is part of the chamber
Banjo = Fuel pipe is attached to a banjo that is bolted to a threaded brass fitting with a side hole in it.

It has to be admitted that some of this information is a bit hazy as Ariel did not always list Amal parts and when they did they were not that accurate about it. Generally Amal’s listings are more accurate but they are a bit inaccurate about the model listings, for instance they list a 498cc KH Red Hunter 1950-54 as having a different specification of carburettor to a 500cc Twin, RH (KH) 1953-54!

The original Amal carburettors were based on the products of the three companies that made up AMALgamated Carburettors Ltd. Initially they had brass bodies and separate float chambers, and were available in 4 body sizes each of which were available in several bore sizes; these were known as types 4, 5, 6 and 29. They were fitted from 1929 until 1933 when the body material was changed to zinc die cast alloy and the model numbers were modified to types 74, 75, 76, and 89. They can be distinguished from the later types because these have four air holes around the base of the body which the next type does not. In 1939 types 274, 275, 276 and 289 were introduced; these have two internal primary air passages in the base of the jet block. A later version with an ‘R’ suffix denotes that the primary air passage hole was moved to the air intake.

 Each type number mentioned above indicates a different size of casting. Each casting was to any one of several bore sizes. Therefore when searching for a replacement carburettor, the bore or choke size is needed in addition to the type. The suffix shown after the type on the flange indicates which jets, float chamber and to which machine it was originally fitted, it is irrelevant providing the body is of the correct size and type and the correct jets etc are used.

For jetting application please select your bike make from the following list.

Ariel, BSA,