The HZ Holden (1977–1980) is one of the most misunderstood but best-driving classic Holdens ever built. From a restoration point of view it has major mechanical differences to earlier H-series cars, especially with the introduction of Radial Tuned Suspension (RTS).
The HZ Holden represents the final and most refined evolution of the classic H-series platform. While it shares visual DNA with the HQ–HX range, the HZ introduced Radial Tuned Suspension (RTS), revised braking systems, updated interiors, and further emissions changes.
If you’re restoring an HZ Kingswood, Premier, Statesman, Sandman, One Tonner or Monaro, this checklist will help you avoid the common trap of buying incorrect HQ/HJ parts that don’t suit the HZ’s unique setup.
HZ Holden Engines & Drivetrain
By the time HZ arrived, Holden had refined its emissions-era engines and improved drivability compared to HX.
Factory Engine Options
- 173ci Red Motor
- 202ci Red Motor
- 253ci V8
- 308ci V8 (ADR27A compliant)
Key HZ note: Many engines received revised carb calibration and ignition tuning to work with RTS and improved braking.
Engine Restoration Checklist
Six-Cylinder (173 / 202)
- Pistons, rings & bearings
- Timing chain & gears
- Oil pump
- Water pump
- Full gasket kit
- Stromberg or Rochester carburettor rebuild kit
- Engine mounts
- Emissions hoses & fittings
V8 (253 / 308)
- Low-compression pistons
- Camshaft suitable for emissions-era heads
- Timing set
- Oil pump
- Quadrajet carburettor rebuild kit
- Harmonic balancer
- Exhaust manifolds
Transmission & Differential (HZ Holden)
Factory Gearboxes
- 3-speed manual
- 4-speed M20 / M21
- Trimatic automatic
- Turbo-Hydramatic 400 (308 V8)
Driveline Parts Checklist
- Clutch kit & spigot bush
- Gearbox rebuild kits
- Shifter bushes
- Tailshaft uni joints
- Differential bearings & seals
- Salisbury LSD (where fitted)
Fuel & Cooling System (HZ Improvements)
HZ cooling systems were marginally improved but still benefit greatly from restoration or upgrades.
Fuel System
- Replacement fuel tank
- Fuel sender unit
- Ethanol-safe fuel hose
- Mechanical fuel pump
- Emissions control hoses
Cooling System
- Radiator (HZ shroud design)
- Fan clutch
- Thermostat
- Heater core
- Correct radiator hoses
Radial Tuned Suspension (RTS) – HZ Exclusive
This is what sets the HZ apart — and what catches many restorers out.
Suspension Checklist
- RTS-specific coil springs
- Matched shock absorbers
- Control arm bushes
- Ball joints
- Rear trailing arm bushes
- Panhard rod bushes
Using incorrect springs or shocks kills the RTS handling advantage.
Steering & Brakes (Major HZ Upgrade)
HZ Holdens received significantly improved brakes.
Steering
- Steering box rebuild kit
- Tie rod ends
- Idler arm
- Rag joint
Brakes
- Larger front disc brakes
- Rear drum rebuild kits
- Master cylinder
- Brake booster
- Brake hoses
Bodywork, Rust & Exterior Trim
Common HZ Rust Areas
- Front chassis rails
- Floor pans
- Inner & outer sills
- Rear quarters
- Boot floor
- Plenum chamber
- Windscreen & rear window channels
- Lower front guards
Exterior Parts Checklist
- HZ grille
- Headlight surrounds
- Tail light lenses
- Bumpers
- Side mouldings
- HZ badges
- Door handles
- Full rubber seal kit
Interior Restoration (HZ-Specific Details)
HZ interiors feature updated trim patterns and improved safety features.
Interior Checklist
- Seat frames & foam
- Correct HZ seat trims
- Door cards
- Dash pad
- Centre console
- Instrument cluster restoration
- Headlining
- Carpet kits
- Steering wheel
Electrical System
Electrical Checklist
- Wiring loom
- Headlights & indicators
- Tail lights
- Alternator
- Starter motor
- Voltage regulator
- Fuse box
Wheels, Tyres & Finishing Touches
Wheels
- Steel wheels
- GTS wheels
- Period-correct alloys
Finishing Items
- Engine bay decals
- Correct fasteners
- Under-bonnet detailing kits
- Period accessories