Build catalogue
Gary Stanfield's 1972 Triumph Stag / Rover 3.9L V8 Conversion
britishv8.orgas published in BritishV8 Magazine, Volume XIX Issue I, December 2011
Photo: britishv8.orgA 1972 Triumph Stag rebuilt with a Rover 3.9L V8 and BMW running gear
Gary Stanfield replaced the Stag's original engine with a fuel-injected Rover 3.9L V8, paired with a Rover five-speed gearbox and a BMW 325i rear suspension transplant. He also reworked the body with new front and rear fenders, shaved trim, and filled seams, finishing on modern BMW Mini wheels. The build mixes engine, suspension, and brake parts from several donor cars into one coherent package, completed in March 2009 and driven over 4500 miles since.
Specs
As the owner states it.
- Engine
- Rover 3.9L with 14CUX (1992 hot-wire type) electronic fuel injection, Viper Cyclone camshaft
- Cooling
- Volvo 740 crossflow aluminum radiator, Saab 900 two-speed electric fan
- Exhaust
- Phoenix tubular manifold, 2 inch custom dual exhaust
- Transmission
- Rover LT77 5-speed, 9.5 inch clutch, BMW driveshaft
- Rear End
- BMW 3.09:1 gears and open differential
- Front Suspension
- Lowered Triumph 2000 crossmember and steering rack, 1.5 inch lowered springs
- Rear Suspension
- BMW 325i E30 transplant
- Brakes
- BMW E30 servo (master), Wilwood four-pot calipers and vented rotors (front), BMW calipers and solid rotors (rear)
- Wheels/Tires
- BMW Mini 17 inch aluminum wheels, 205/50/R17 front and 215/50/R17 rear tires
- Instruments
- stock
- Interior
- stock
- Body Mods
- Bumpers removed, front and rear fenders replaced, chrome trim shaved, body seams filled
- Electrical
- Stock, except 14CUX engine electrical controls
- Completed
- March 2009, driven 4500 miles as of July 2011
Parts used
What the owner names in the write-up, grouped the way the Parts page groups them. Where one of the shops we index lists the same thing for this car, it is shown underneath with a link to the shop.
Engine 3
- Rover 3.9L V8 engineRover
Replaced the original Triumph engine, fitted with electronic fuel injection
- 14CUX electronic fuel injection system (1992 hot-wire type)
Provides engine management for the Rover V8 swap
- Viper Cyclone camshaftViper
Fitted to the Rover V8 for the conversion
Fuel & Ignition 1
- Phoenix tubular exhaust manifoldPhoenix
Header fitted to the V8 for exhaust flow
In the shops
Tubular Exhaust Manifold - Sprite/Midget ↗Betaset (France)· €382.50 EUR
Manifold-Tubular FREE FLOW ↗MGbits4U· £0.00 GBP
LCB Maniflow Steel Tubular Manifold - Mini ↗
Cooling 2
- Volvo 740 crossflow aluminum radiatorVolvo
Used for cooling the V8 conversion
In the shops
Volvo Distributor Rotor ↗
Sports & Classics· $19.95 USD
NC Aluminum Race Radiator ↗
Flyin' Miata· $549.00 USD
Koyo Crossflow Radiator Drain Plug ↗Flyin' Miata· $12.99 USD - Saab 900 two-speed electric fanSaab
Paired with the Volvo radiator for cooling
In the shops
Saab 900 Exhaust Clamp ↗Sports & Classics· $8.95 USDTwo-Speed Wiper Switch ↗Motaclan Limited· £22.58 GBP
Saab 900 Input Shaft Nut ↗Sports & Classics· $16.95 USD
Gearbox & Drivetrain 4
- Rover LT77 5-speed gearboxRover
Manual transmission fitted behind the V8
In the shops
Clutch Kit, 3-piece (Rover V8, 5-speed) ↗
bpnorthwest.com· $633.53 USD - 9.5 inch clutch
Matched to the LT77 gearbox
- BMW driveshaftBMW
Connects gearbox to the rear differential
In the shops
BMW Driveshaft Center Support ↗Sports & Classics· $59.95 USD - BMW 3.09:1 open differentialBMW
Rear end gearing used in the conversion
Suspension & Steering 3
- Triumph 2000 front crossmember and steering rackTriumph
Lowered and used for the front suspension setup
In the shops
Front Stub-Axle D-Washer (Triumph range) ↗
Racetorations· £2.25 GBP
Front Crossmember Bush (Steering Rack Mounting, Stag/2000 Power Steering) ↗James Paddock Ltd· £1.80 GBP
Gear Lever Spring Retainer (Used) - Triumph TR2 to TR6 ↗Racetorations· £10.00 GBP - 1.5 inch lowered front springs
Lowers the front ride height
In the shops
Front Coil Spring Pair, Lowered 1" (Terrafirma) ↗
Moss Motors – Triumph TR6/TR250· $155.75 USD
Rear Coil Spring Pair, Lowered 1" (Terrafirma) ↗Moss Motors – Triumph TR6/TR250· $165.00 USD - BMW 325i E30 rear suspensionBMW
Full rear suspension transplant from a BMW E30
Brakes 3
- BMW E30 brake servoBMW
Used as the master brake booster
- Wilwood four-pot front calipers and vented rotorsWilwood
Front braking upgrade for the conversion
In the shops
Wilwood Caliper Piston Seal Square Ring Kit (6-Piston Front) ↗Flyin' Miata· $21.99 USD
Wilwood Caliper Piston Seal Square Ring Kit (4-Piston Front, 1.38") ↗Flyin' Miata· $12.49 USD
Wilwood Rotor Hat ↗Flyin' Miata· $179.00 USD - BMW rear calipers and solid rotorsBMW
Rear braking components sourced from BMW
In the shops
Front Left Brake Caliper (Solid Disc) ↗Moss Motors – Triumph TR6/TR250· $226.25 USD
Front Left Brake Caliper (Solid Disc) ↗Moss Motors – Triumph TR6/TR250· $102.75 USDFront Right Brake Caliper (Solid Disc) ↗Moss Motors – Triumph TR6/TR250· $226.25 USD
Wheels & Tyres 3
- BMW Mini 17 inch aluminum wheelsBMW Mini
Fitted to give a modern stance to the Stag
In the shops
Automatic Front Exhaust Pipe (Mini, 1992-97) ↗Angloparts· €0.00 EUR
Exhaust Sampling Pipe, 1275cc (Mini, 1992-94) ↗Inlet & Exhaust Manifold, Single HS4 - Mini 1974-1992 ↗ - 205/50/R17 front tyres
Front tyre fitment for the new wheels
In the shops
Inner Tube (16 x 205 Tyre) ↗Moss Motors – Triumph TR6/TR250· $24.75 USD - 215/50/R17 rear tyres
Rear tyre fitment for the new wheels
Body & Trim 1
- Replacement front and rear fenders
Fitted to replace rusted or damaged original panels
In the shops
Rear Half of Front Fender, R/H ↗Moss Motors – Triumph TR6/TR250· $704.83 USD
Rear Half of Front Fender, L/H ↗Moss Motors – Triumph TR6/TR250· $704.83 USD
Other 1
- 2 inch custom dual exhaust
Custom-built exhaust system for the V8 swap
Photos
All 14 pictures in the write-up, in the order they were posted, shown from britishv8.org. A picture opens larger here, with the way through to the page it is on.
How it was done
Starting point
Gary began with a 1972 Triumph Stag in need of restoration. Before any mechanical work, the car needed rust and body repair addressed, as shown by the original 'before' condition of the car.
Body repair and reshaping
New front and rear fenders were fitted to replace rusted originals. Gary smoothed the panels and chose to leave the original chrome side trim off for a cleaner look. Bumpers were removed and body seams filled to further tidy the exterior.
Engine swap
The Triumph engine was replaced with a Rover 3.9L V8 fitted with 14CUX electronic fuel injection and a Viper Cyclone camshaft. A Phoenix tubular exhaust manifold and custom dual exhaust were built to suit the new engine.
Drivetrain changes
Power goes through a Rover LT77 five-speed gearbox with a 9.5 inch clutch and a BMW driveshaft, to a BMW-sourced rear end running 3.09:1 gears with an open differential.
Suspension and brakes
The front end uses a lowered Triumph 2000 crossmember and steering rack with 1.5 inch lowered springs. The rear suspension is a BMW 325i E30 transplant. Braking combines a BMW E30 servo with Wilwood four-pot front calipers and vented rotors, and BMW calipers with solid rear rotors.
Wheels and finishing touches
BMW Mini 17 inch aluminum wheels were fitted with 205/50/R17 front and 215/50/R17 rear tires, giving the lowered Stag a more aggressive stance. The interior and instruments were left stock, and the car was completed in March 2009.
A summary in our own words. The full account, with all its detail, is the owner's: read it at britishv8.org ↗
Worth knowing
- Mixing components from several donor cars (Rover, BMW, Volvo, Saab) can be combined into one working V8 conversion.
- Lowering the front springs and fitting larger modern wheels changes the car's stance noticeably.
- Careful smoothing of new fenders can allow chrome side trim to be left off for a cleaner look.
- Upgrading brakes with Wilwood front calipers alongside a BMW servo and rear calipers balances braking for the added power.