I have a 96 Fiesta with 74000 on the clock, the car overall goes very well except at high revs around 4000 she slows down as if it had fuel starvation, past 4000 revs the car regains speed but not in a smooth way. I would like to point out that at 72000 miles the valve clearance was done and they were put as directed by the manufacturer 0.20 inlet 0.30 outlet, to my knowledge Fiestas built after Nov 97 have the outlet at 0.50 and somebody suggested that even on the previous Fiesta engines to set the outlet at 0.50.
Can anyone else give me any suggestions if the problem could be related to the valve clearance or what else it could be.
Many Thanks,
Gerry

 

Well, the valve clearances are different depending on the engine. After about 2001, the tappets are adjusted different. This is because they ARE different.

There is a plate riveted to the rocker cover on later models which has the settings on.

If yours is an early engine and has been set up to late specs, I would reset them to the correct settings before I did anything else.

 

Thanks Ian

I set the valves as my book suggest , so they are at 0.20, 0.30 , I wasn't going to do different , I just had this doubt in my mind if the valves my need to be set different for any other strange reason.
Do u have any suggestion for that strange behaviour that the car have, i must point out that i cleaned any air conduct , there is new oil , filters , and spark plugs , plus a new fuel filter .
Many thanks

Gerry

 

Does anyone have a suggestion? , or is better to write this post in another space .

Ciao

 

May be an idea to get the diagnostics checked? Possibly Mass Airflow sensor at the airbox - daughters 1.25 Fezz had a 'flat spot' at 4k which was caused by that. It now runs much better at the top of the rev range.