Hi!

My 340 1.7 always had this problem since the beginning: if you drive too much time at high revs it goes off and to get it back on takes some time.

I have replaced the carb a few times already, and now it has a weber in pretty nice condition but the problem is still there.
It's not a electrical problem, nor ignition, nor distributor.

Yesterday i discovered something: if the vacuum hose from the electrical ignition is connected to the carb, it only takes a few yards of high revs driving to cut out. If the hose is not connected, it takes much more to cut out.... Sometimes you can drive 10... 20 miles with any problem. But the cut out condition is still there.

Can someone explain why this happens? And what do you think it may cause the cut out?

I suspect something is out of adjustment in the carb and is flooding the engine at high revs. When you disconnect the vacuum hose, you're introducing an air leak into the system so I would guess its making the mixture leaner just enough to stop the over rich situation.

Hope that helps.

pettaw wrote:I suspect something is out of adjustment in the carb and is flooding the engine at high revs. When you disconnect the vacuum hose, you're introducing an air leak into the system so I would guess its making the mixture leaner just enough to stop the over rich situation.

Hope that helps.

I always thought that the problem might be flooding, and probably with the heating the intake air leaks from the gasket and like you said, maybe the vacuum hole in the carb helps compensate the leak. Thanks for your help