NSB Concept

Reinforced valve spring kit Mazda FS

€630.52 (tax incl.)

Reinforced valve spring kits for the Mazda 2.0 with FS engine.

  • Brand: SUPERTECH
  • Engines: FS 2.0 16V (626, MX-6, 323, MPV II)
  • Springs: single or double
  • Contents: springs, upper retainers, lower spring seats and stem seals depending on the kit
SPRK-MP20S
On order, 15 to 30 days lead time
Pay in installments

Mazda FS engine covered

The FS is Mazda's 2.0 litre four-cylinder with 16 valves. It sits under the bonnet of the 626, the MX-6, the BJ-generation 323 and the MPV II people carrier from 1991 to 2006.

The kit replaces the original spring and its upper retainer.

SUPERTECH reinforced valve spring kit

Once the cam has done its push, only the spring can close the valve again. At high revs its inertia makes it lag: too little load and it lands late, bounces or even strikes the piston, hence the term valve float.

Seat pressure: 258 N at 34.8 mm (SPRK-MP20S, single springs), 378 N at 34.8 mm (SPRK-TC25D-MP, double springs).

Valve spring kit technical specification

Part numberBrandSpringsOuter / inner ØSeat pressureOpen pressureRateMax liftKit contents
SPRK-MP20S SUPERTECH Single Outer 25.0 / 18.0 mm 258 N at 34.8 mm 14.4 mm Springs, titanium upper retainers
SPRK-TC25D-MP SUPERTECH Double Outer 25.0 / 18.0 mm
Inner 18.0 / 13.0 mm		 378 N at 34.8 mm 14.4 mm Springs, titanium upper retainers, lower spring seats, valve stem seals

Valve spring kit fitting details

PartMazda originalReinforced spring kit
Spring Kit specific: SPR-TC25S or SPR-TC25D
Retainer Kit specific: RET-2500/T1
Spring seat Double spring kit specific: SS-3012
Collets

The SPRK-MP20S gathers SPR-TC25S single springs and RET-2500/T1 titanium upper retainers. The SPRK-TC25D-MP combines SPR-TC25D double springs, the same upper retainers, SS-3012 lower spring seats and VS-T6SM valve stem seals.

With the spring fitted and the valve shut, you measure installed height from the lower seat to the retainer. Each load quoted holds at that figure only: lengthen it, after a head skim for example, and the load drops following the rate. Heights and loads of both kits are set next to each other in the table below, so the two can be compared at a glance.

SUPERTECH
Installed height 34.8 / 34.8 mm
Seat pressure at this height 258 / 378 N

Technical guide

Our brands

SUPERTECH SUPERTECH is a Californian maker of valvetrain parts for racing, active in this market for over thirty years. Before shipping, each lot of springs is inspected by laser, X-ray and ultrasound, so that any flaw in the wire material is rejected before the kit ever reaches you.

How to choose

With a firmer spring the valve follows the cam at speeds where the stock setup falls off: you can raise the limiter, pick a sharper camshaft or run boost without float. The SPRK-MP20S gives 258 N at the seat and the SPRK-TC25D-MP 378 N, at the heights shown in the preceding table. Maximum lift is 14.4 mm for both kits: a camshaft lifting further would go beyond what the springs accept.

CriterionKey point
Choosing the pressure 58 and 85 lbs: these are the seat loads of each kit, shown in newtons in the table. Three things decide the right pick: how far the camshaft lifts, how high the engine will rev and whether a turbo blows; each one asks for extra spring. An over-stiff spring gains nothing and wears out the tappets and the lobes.
Single or double spring On the SPRK-MP20S a single, softer spring sits on every valve; the SPRK-TC25D-MP nests two firmer ones and adds an SS-3012 lower spring seat with VS-T6SM valve stem seals. Both kits share the same titanium RET-2500/T1 upper retainer. The choice is therefore made first on seat load, then on spring type.

When reinforced springs become necessary

  • Camshaft lifting higher than stock
  • Limiter raised to rev higher
  • FS engine with a turbo or supercharger fitted
  • Head refreshed for circuit or rally work
  • Worn springs, valves floating before the limiter

Compatible vehicles

ModelEngine codePowerYears
Mazda MX-6 (GE) 2.0 FS 115 hp 1992-1997
Mazda 626 IV (GE) 2.0 i FS 115 hp 1992-1997
Mazda 626 IV (GE) 2.0 i 4WD FS 116 hp 1992-1997
Mazda 626 III Station Wagon (GV) 2.0 GLX FS 117 hp 1992-1995
Mazda 626 V (GF) 2.0 FS 115 / 126 hp 1997-2006
Mazda 626 V (GF) 2.0 AWD FS 140 hp 1997-2002
Mazda 626 V Station Wagon (GW) 2.0 FS 116 / 126 hp 1998-2002
Mazda 323 S VI (BJ) 2.0 FS 133 hp 2000-2004
Mazda 323 F VI (BJ) 2.0 FS 133 hp 2000-2004
Mazda MPV II (LW) 2.0 FS 120 / 133 / 135 hp 1999-2006
Important: one kit is enough to equip the engine, with single or with double springs. The codes FS2C, FSZE, FS7E / FS7G and FS-DS are not covered on this page.

Related products

Cylinder head removed? Get the valves and guides inspected too and save a second teardown. The links below lead to the FS valves, inlet then exhaust:

Mazda FS inlet valves →
Mazda 323 626 MX-6 2.0 FS exhaust valves →

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