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Triumph Repair/Carburetion...


Hi Howard,

I have a 150 CD on my '79 Spitfire. I have rebuilt it but seems I never have all the parts in the kit I need. Obviously it hasn't been completely successful. My question, this carb has the automatic choke. I have set it per directions but how do I know it is actually choking as it should being there is no actual choke butterfly to see the action? The car is hard to start.

Hi Steve,

There is a simple test. Just before you try to start it cold and you are sure it is going to be difficult to start, just spray a little "Starting Fluid" into the intake. (avaiable at most any auto parts stores)

If it starts ritght up but then seems cold nature just give it a couple more shots of starting fluid.

This will establish that the hard starting is a lack of fuel.

The Stromberg auto chokes are noted for failing. If this is the type with the two small coolant lines on a unit on the side of the auto choke and it has one bolt in the center and two screws holding the unit to the rest of the auto choke. Don't remove the center bolt but do remove the two screws holding it on the main body of the choke assembly and move it away from the main body. You will see a short lever sticking out of the main body that engaged the bimetal spring. You can then operate the lever in it's slot to manually operate the choke.

If you can operate the choke manually then note if the bimetal spring is not broken and that the lever was engaged with the end of the spring. If it all looks ok up to that point you can try to rotate the unit so as to fully engage the choke (after it is cold)

The auto chokes fail so often that several companies have been producing a conversion to a manual choke for the Stromberg carburetors.

You can check with Moss Motors as they use to have the conversion.


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Howard M. Fitzcharles III


Triumph TR-4 up & Spitfire, and Engine theory


Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

Associate member SAE EAA member

Import Car magazine

ASE Master Auto with L-1 certification up to 2000

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