NSB Concept

Reinforced valve spring kit Mitsubishi 420A

€887.66 (tax incl.)

Reinforced twin valve spring kit for the Mitsubishi 420A 2.0 16V engine.

  • Brand: SUPERTECH
  • Engine: 420A
  • Springs: twin
  • Contents: springs, upper retainers, lower spring seats
SPRK-TS1015-NE
On order, 15 to 30 days lead time
Pay in installments

Mitsubishi engine covered

This kit is intended for the 420A, the 2.0 litre 16-valve engine of the Mitsubishi Eclipse II (D3_A) 2.0 RS, built from 1995 to 1999.

The kit's twin springs replace the standard ones: each valve receives an outer and an inner spring, fitted with their seats.

SUPERTECH reinforced valve spring kit

The spring has one precise job: to return the valve to its seat as soon as the cam has released it. As revs climb, the valve obeys too slowly, bounces, closes late and can hit the piston. A firmer spring removes that fault.

This kit announces 374 N on the seat at an installed height of 34.6 mm. The technical table gives the full detail.

Valve spring kit technical specification

Part numberBrandSpringsOuter / inner ØSeat pressureOpen pressureRateMax liftKit contents
SPRK-TS1015-NE SUPERTECH Double Outer 27.5 / 20.0 mm
Inner 20.0 / 15.2 mm		 374 N at 34.6 mm

Valve spring kit fitting details

PartMitsubishi originalReinforced spring kit
Spring Kit specific (double)
Retainer Kit specific
Spring seat Kit specific
Collets Original kept

The SUPERTECH kit includes the twin springs, the upper retainers and the lower spring seats; the original collets are kept.

Installed height means the gap separating the two seats while the valve rests on its seat. For this kit, the 374 N load is given at 34.6 mm. The more this distance grows, the more the load falls, following the spring rate: the figure therefore matters a great deal when assembling. The neighbouring table repeats the reference value.

SUPERTECH
Installed height 34.6 mm
Seat pressure at this height 374 N

Technical guide

Our brands

SUPERTECH SUPERTECH is a California maker of valvetrain parts for motor racing, active for over three decades. Its springs are wound from steel wire alloyed with chrome, silicon and vanadium, and every batch is examined before delivery with ultrasound, radiography and a laser check.

How to choose

Twin springs keep the valve faithful to the cam profile much higher in the revs than a stock set-up: the rev limiter can be raised, a sharper camshaft fitted or a turbo added without float returning. The kit gives 374 N on the seat at 34.6 mm installed height. The choice of revs stays with the tuner, but the load margin avoids many surprises, on track as in rallying. The softer original springs leave little reserve once the engine is pushed harder.

CriterionKey point
Choosing the pressure The figure 84 lbs states the seat load, that is 374 N. To decide, count on cam lift, the revs to reach and any forced induction; each of these demands more load as it increases. A load above the need serves no purpose and speeds up camshaft wear. It is better to pick a measured load that matches the engine's real state of tune.
Single or double spring Two nested springs on each valve, 27.5 and 20.0 mm in outer diameter: a more heavily loaded set-up than a single spring, but bulkier. Upper and lower seats come with the kit; the original collets are still used.

When reinforced springs become necessary

  • Camshaft sharper than the standard one
  • Rev limit raised clearly
  • Turbo installed, or boost pressure raised
  • Head redone for the track or rallying
  • Worn springs, or float felt before the limiter

Compatible vehicles

ModelEngine codePowerYears
Eclipse II (D3_A) 2.0 RS 420A 1995-1999
Important: this kit targets only the 420A of the Eclipse II 2.0 RS. Eclipses with the 4G63 engine are not covered.

Related products

Cylinder head removed? Use the strip-down to have the exhaust valves and their guides checked before reassembly. The matching article for this engine:

Mitsubishi Eclipse 420A exhaust valves →

3 other products in the same category

Viewed products