for 1st generation engines with hydraulic tappets, single groove valves and cylindrical valve springs (until '97)

It is very important to verify the OEM spring type in your engine:

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The oldest ZETEC hydraulic tappet engine has cylindrical valve springs, which allow a maximum lift of only 9,0mm

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The newer ZETEC hydraulic tappet engine has tapered valve springs which allow a maximum lift of 11,0mm

engine with cylindrical valve springs: single spring [ref. 902-0015] can be used on OEM retainers, or on retainers [ref.99312]

engine with tapered valve springs: single spring [ref. 902-0015] can only be used on retainers [ref.99312]

FOR COMPETITION APPLICATIONS ONLY. Following details must be verified:

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the camshafs must turn smooth in the cylinderhead, provide free travel by machining where needed

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distance between valve seal and retainer at full lift must be 0.6mm at least

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minimum valve spring travel of 1.0mm at full lift must be provided

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distance between valve and piston 1.0mm (pref. 1.5mm). check 5-15° before TDC on exhaust, and after TDC on intake

ONLY for use in competition engines with independent engine management (throttle position sensor) or carburettors