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Triumph Repair/spitfire 1500


my spitfire starts but will not idle ,  i have to keep foot on the throttle around 1700-2000 rpms to keep it running.

thoughts on my issues?  thanks for you advice

have a GREAT weekend

Hi Steve,

A condition of not running at idle can be caused by many things so you will need to test a few things to narrow the problem down to a small area.
First set the RPM at the lowest that it will run steady at hold it there. Have someone helping or you can adjust the throttle stop screw to do that.
Now put your hand over the opening of the air filter but with your fingers spread apart so as not to restrict the air flow. Now, SLOWLY start closing your fingers together so as to start restricting the air flow. If in that process the RPM speeds up or the engine smooths out then that is a sure indication you have a major air leak either in the gasket of the carburetor to maifold or manifold to head. Or you have a major air leak in a vacuum line.

If it did smooth out or speed up then start pinching off vacuum hoses to see if any are at fault especially the large one to the brake booster. If you have an EGR valve you may need to remove the valve and clean it as you can't pinch off any large pipes as they are metal. Only the small vacuum hose can be pinched to test it. The valve itself can get stuck open and allow exhaust to enter the intake.

Other things that can cause no low RPM running are inside the carburetor. You said you have a 1500 but you didn't say what year. Does you car have a single Stromberg carburetor or does it have dual SU carburetors? I can probably help in that area too if you will tell me which you have.

Let me know,


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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.

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