engine splutter

[Keithver]

When changing down from 5th gear to 4th to overtake, my engine would splutter until I changed back up to 5th. I've just serviced the car. I see that the old plugs were Champion N9Y. on inspecting them they had all burnt pretty well. no indication of a rich mixture. I have fitted the specified N7Y plugs. Old and new plugs were set to 0.6mm gaps.
I took it for a drive and revved it to about 6000 rpm in all gears. I could not get it to splutter at all.
Just wondering - could the plugs make such a difference. I didn't fiddle with the carbs at all

[lancianut666]

Water in the petrol?

[Keithver]

I don't think so. I drained the tank and didn't see any water

[lancialulu]

Not really enough information.....

[Keithver]

hi Tim. What other info can I send you to help you understand the problem better

[lancialulu]

Is it happening all time you change from 5 to 4th? What carbs do you have the nasty emission ones?

What revs are you in in 5th when you change down. Does it also happen in other gears changing at same revs?

[Keithver]

I have the standard Solexes - not the emission ones
When I change down from 5th I'm probably between 3 and 3500 RPM and it mainly happened when changing down from 4th.
As I said initially, the only thing I changed during the service was the plugs - to the correct N7Y's. Could it be that the plugs would make such a difference. More out of interest than anything else as the problem seems to be resolved now

[lancialulu]

Incorrect valve timing can cause the Fulvia engine to "stagger" around 2000 rpm under load as the incorrect timing causes a hole in the torque curve....

[Spider2]

Try driving with the headlights on!
I had  splutter at 3,000 rpm. I have a 123 electronic ignition fitted and it was traced to the voltage regulator overvolting at high rpm causing the electronic ignition to cut out (they are very voltage sensitive). I noticed that it never spluttered at night. I changed to a modern solid state VR. Problem solved. What sort of VR do you have?