1. Stromberg Cd 175 Carburetor
2. Stromberg 175 Cd 2 Manual

Zenith-Stromberg 175 CD2 SE units were used on 1970 140 series models, and on. Read the instructions and study the exploded view of the carburetor. Screw and locknut on my Zenith Stromberg 175 CD-2 carburetors? Could wish to know about these carbs, a lot more than in the manual!

As far as I know the MGB always had the ZS with a float bowl plug, but I could be wrong. Have you tried any Triumph sites? TRs used many variations of the 175CD-2. If you need a replacement stock carb I've got a spare one. You just have to supply the heat mass for the auto choke. Eric Triplett 'Electronic ignition, the greatest thing that ever happened to carburetors.' 1968 High Compression Engine, Dual SU HIF-4 Conversion, Peco Header and Exhaust, Pertronix LU-147, MSD Blaster 2 Coil.

Advanced Distributors Re-Cruve 45DM.

A Stromberg carburettor The Stromberg CD carburettor, like the SU (See ), is a constant-depression carburettor, hence the CD. The two work in much the same way, but the Stromberg differs in having an air valve - commonly called the piston - surrounded by a rubber diaphragm in the dashpot.

The size and type of a Stromberg are given by numbers and letters. Numbers such as 125, 150 and 175 are sizes: they mean a choke diameter of 1 1/4, 1 1/2 and 1 3/4 in. The size makes no difference to the way you tune the carburettor.

Types include CD, CDS, CD2S and CD3, all used on older cars made before anti-pollution laws demanded emission-control fittings. Later types with emission control have the letter E, as in CDSE and CD2SE. Tuning methods vary according to type, but Strombergs are not stamped with their type marks. Information in the car handbook should help you to identify your type.

Air cleaners. Leave the air cleaner in place if you can, so that adjustments are made with the carburettor as close as possible to its normal working condition. However, this may not be possible, depending on the car, the type of carburettor and the adjustment being made. Before starting to tune the carburettor, check out all the other systems such as sparkplugs, contact-breaker gap and the ignition timing (See ). Although valve clearances seldom need resetting between major services, always check them before attempting to tune the carburettor. Check, too, that the damper tube is topped up with oil to within 1 in. (6 mm) of the end of the rod.

Use ordinary multigrade oil or the special SAE 20 oil made for the purpose by Zenith (the makers of Stromberg carburettors). Tune with the engine running at working temperature. Adjusting the gap Adjusting the gap The fast-idle stop screw opens the throttle when the choke is pulled out. There must be a gap between its head and the choke cam when the choke is pushed home.

The CD and CDS have different cold-starting devices, but the adjustment works in the same way. Set the gap according to the car-makers recommendations - usually about 1mm.

Some Strombergs have a two position screw to limit the use of the choke according to the season. It has a spring under its head. Set it with the spring compressed for summer and the tension released for winter (only necessary in freezing weather) Tuning the CD, CDS and CD2S. If there is no pin, lift the piston with a screwdriver. If there is no pin, take off the air filter and lift the piston 1/32 in.

(1 mm) with a thin screwdriver. Listen to the engine note while you do so. If the mixture is correct the engine speed should rise slightly for a moment, then return again to normal. If it rises and stays fast the mixture is too rich. If the engine dies when the pin is lifted, it is too weak.

Switch off the engine before adjusting the mixture, and check that the jet needle is central. Remove the air cleaner, lift the piston and let it fall. If the jet is central, the piston falls with a sharp click. Keep the jet central while you adjust the mixture by taking the damper rod out of the top of the carburettor and pushing a pencil or soft metal rod firmly down the hole to hold the jet in place. Make sure that the jet remains centralised. Use a coin to turn the jet-adjusting screw one-eighth of a turn at a time, waiting each time for the engine speed to settle down.

Screwing upwards weakens the mixture, downwards enriches it. Start the engine and bring it up to working temperature. The mixture-adjusting screw is set centrally in the base of the carburettor on CD, CDS and CD2S models. It is brass and has a wide slot in it.

Although a screwdriver can be used to turn it, a small coin is easier. Turn only an eighth of a turn at a time, then wait about 15 seconds for the engine speed to settle down. Lift the pin again and see whether the engine speed alters. Screw the jet upwards (that is, anti clockwise looking down on the carburettor) to weaken the mixture, or down (clockwise) to make it richer. With the mixture setting correct, the idling speed may now be too fast or slow.

For most cars it should be 850-950 rpm - judge it by ear if your car does not have a tachometer (or rev counter). Adjust the idling speed by turning the throttle-stop screw.

Stromberg Cd 175 Carburetor

If tuning fails to make the engine run properly, the carburettor may need cleaning (See ), or the air filter renewing. Centralising the jet.

Stromberg 175 Cd 2 Manual

Lift the piston while you adjust the height with a coin. Lift the piston so that the needle is clear of the jet, and screw the jet adjusting screw up until the top of the jet is just above the top of the bridge in the carburettor bone. Use a spanner to slacken the large nut just above the jet adjusting screw by half a turn.

That releases the jet in its housing, but allows it to drop slightly. Wind the jet adjuster up again until the top of the jet is level with the bridge. Let the piston fall back gently so that the needle centralises the jet. Remove the piston damper and hold the piston down with a pencil or soft metal rod slipped into the damper tube. Tighten the jet assembly.

Check several times that the piston drops with a click. The CD3 is a fixed-jet carburettor and you need a special tool to reset the mixture control, which is done by altering the height of the jet needle. The CD3 carburettor has a fixed jet, and the needle is loosely mounted in the air valve, or piston, so that it centres itself. You need a special tool to reset the mixture, which is done by altering the height of the needle in the piston. The tool is a long L-shaped hexagonal Allen key which goes inside a thick-walled tube. Its maker's part number is B20379. To use the tool, remove the dashpot damper and insert the tube in its place.

Turn the tube until a pin on its side falls into a slot in the air-valve shaft. Use an Allen key to set the needle in a midway position. The right position is when depending on the needle fitted - the washer around the needle or the groove in it is flush with the bottom face of the air valve. Reassemble the carburettor and adjust the needle - starting from this point - no more than one turn either way. After each adjustment is made, run the engine at about 2,000 rpm for ten seconds or so to clear the extra fuel which tends to get into the inlet manifold when you are making an adjustment. If you do not have a revolution counter or tachometer, listen to the engine note. Its pitch should rise a little more than an octave above its normal sound when idling.