Odd misfire…middle of France.

[Nigelblandin]

Hi all, started a trip this evening and had to use the autoroute. Sitting at 60-65mph for a couple of hours perfectly. Then suddenly started missing and losing power.
Pulled out the choke half way and all is normal again.
Any ideas?
Not too hot, half a tank of fuel.

It is a cool, foggy evening. Long constant running, possible carb icing?
I don’t have the flexible pipe from the exhaust….

 

[jcarruthers2]

Hi Nigel

On the ignition side it could be the condenser or coil, points/contact set closing up, faulty spark plug/gap closing up/faulty HT lead. Carburation too of course, dirt in carb. Has the breather pipe with the one way valve in it, which runs from rear of base of carb/manifold to rocker cover come adrift? Sometimes this hose splits or the one way valve is faulty.

 

[malcolm]

Blocked main jet. If it works again after the car has been stationary for a couple of minutes it'll be due to carb icing.

 

[Piet]

Along the same lines if it persists could be a intake manifold air leak, loose carb or manifold bolts etc.