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You are here: Experts > Home/Garden > Auto Repair > Triumph Repair > TR6 Fast idle and lean mixture
Triumph Repair - TR6 Fast idle and lean mixture
Expert: Howard M. Fitzcharles III - 11/2/2009
Question
Greetings
I have a 1970 TR6 USA engine and it is testing lean at idle even when the needles are fully withdrawn. It also idles at about 1200rpm with zero adjustment on the idle screws. Both carbs behave the same.It has no EGR system.
I note that the ignition retard(?) line is missing from the distributor.
Where should this be connected to carbs or manifold?
Thanks for any help.
Peter
Answer
Peter, If you have no EGR system than there is no need for a vacuum port on the carburetor. Some of the early TR-6s came with a vacuum advance and a vacuum retard unit on the distributor but the factory just blocked off the vacuum advance unit and only used the vacuum retard unit which used manifold vacuum (straight vacuum)
There is a basic fact about all engines and that is none can run at 1200 RPM without a good supply of air. Also, if both throttle plates are fully closed there is no way for fuel to get in so how can it be running at 1200 RPM? You need to remove the carburetors and see what is wrong with the throttle plates as to why they are not closing. Also check the decel valves on each carb. These can allow air to bypass the throttle plates. The diaphragms get hard and can hold the small disk off of the seat. There is an adjusting screw that makes it possible to put a load on the valve to keep it closed all the time thus preventing a valve from sticking open.
Howard
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