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Checking and cleaning a GM Varajet carburettor

Here you can get Checking and cleaning a GM Varajet carburettor, Checking the needle valve and Adjusting an automatic choke ect.

The Varajet carburettor used on many Vauxhalls and Opels is a hybrid between fixed-jet and variable-jet (for example, SU) types. It is as sensitive to dirt and sediment as any fixed-jet carburettor, and needs careful cleaning about once a year.

GM Varajet carburettor

The Varajet has two chokes or barrels. The first, which works alone at low engine speeds, features a fixed- jet system. The second, which comes in at higher speeds, features a variable jet. As with any carburettor, remove it from the car (See Removing a carburettor for cleaning ) for cleaning. Wash parts in petrol, using lint-free rags to wipe them. Renew all gaskets . After reassembly, oil the external moving parts.

The carburettor has the layout of a traditional fixed-jet type, and is dismantled in much an equivalent way. Take an equivalent precautions against dirt and therefore the loss of small parts (See Checking and cleaning a fixed-jet carburettor ). Make notes or drawings of any parts dismantled, to assist refitting. Try to not disturb the settings of adjuster screws, but if you are doing , make sure that you come back them to their original setting by counting the amount of turns taken to get rid of them.

Stripping the body

Disconnect the linkage among the throttle and the choke through straightening the split pin and pulling it out. Use a brand new cut up pin while you reassemble.
Remove the screws holding at the top and lift it off. Unlike most present day fixed-jet carburettors, the float isn’t always hung from the top, and so stays in place. Be careful not to bend the various tubes protruding from the bottom.

The accelerator pump , which features a spring thereunder, may leap out. If it doesn’t, lift it out carefully. there’s a ball under the spring which falls out once you turn the body over, so be able to catch it. There is also another, larger ball within the suction-valve spring housing next to the pump.

This will not begin unless you’re taking the screw out above it and extract the spring with very long-nosed pliers. don’t do that unless you’ve got to examine a broken spring or a blocked jet under the ball. Peel off the old gasket, making a note of how it fits in order that you’ll fit the new one in just an equivalent way.

Rinsing out the float chamber

Lift out the upper packing piece. Examine the float valve to ascertain how the valve spring hooks on to its platform. Unhook the spring and take away the float pivot clip in order that you’ll lift the float out. The needle will come too, hanging from the top of the float. Lift it off.

Pull out the lower packing piece to leave the float chamber empty. Rinse out the chamber with a little petrol and wipe it clean with a lint-free rag. Remove all sediment, but do not bother about surface staining.

When refitting the float, remember to hook the valve spring back into place. The float level is not adjustable. As with any carburettor, the various parts are a precision-fit, and care must be taken to handle every part gently. Before finally tightening the screws holding the carburettor top, ensure that the accelerator-pump piston moves freely.

Partial-load needle

This needle moves up and down in a drilling midway between the two barrels of the carburettor. It is moved by a piston beside it, connected by a link at the top. The needle is extremely easily bent, so disconnect the link before removing either the needle or the piston. Push down the spring under the ball head of the needle. Lift the top slightly to free the link. Push the link aside.

Lift the needle out carefully. Unscrew the jet into which it fits employing a snug-fitting screwdriver. Check both needle and jet for wear, which might cause erratic running and waste fuel . Signs of wear and tear will show as minute groves within the jet or on the needle or bright spots on the side of the needle. Replace them if there’s the slightest sign of wear and tear , also if the needle is bent.

Checking the needle valve

Check the float needle valves for wear. Both the needle and its seating should last for several years, but when either gets worn there may be persistent flooding . If necessary, fit a new valve; on some carburettors the valve is not renewable – fit an exchange carburettor.

Adjusting an automatic choke

The choke setting is adjustable for summer or winter. The adjustment is made through moving a pointer connected to the choke frame along a graduated scale. An average setting for all seasons in Britain is one one mark to the proper of the centreline. In very cold weather move the pointer further towards ‘R’ (rich) and in hot weather towards ‘L’ (lean). Loosen the three surrounding screws to make the adjustment and retighten them after changing the setting.

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