Build catalogue
Derek Costello's 1974 TR6 Ford 302 V8 Conversion
britishv8.org
Photo: britishv8.orgA 1974 Triumph TR-6 rebuilt around a Ford 302 V8
Derek Costello swapped his TR-6's original engine for a rebuilt Ford 302 V8 paired with a T5 five-speed, reworking the frame, tunnel, suspension and brakes to suit. The write-up covers the engine fitment, custom fiberglass transmission tunnel, and detailed front and rear suspension work, giving other TR-6 owners a practical reference for a similar conversion.
Specs
As the owner states it.
- Engine
- Rebuilt Ford 302cid V8 with Edelbrock E-Street aluminum heads, Edelbrock camshaft, roller lifters, Edelbrock Performer 289 low-rise intake, Edelbrock 500cfm carburetor, HEI distributor, AC Delco 8mm silicone plug wires, Ford Racing valve covers
- Cooling
- 19" by 24", 3-row, cross-flow aluminum radiator with 16" Kenlowe electric fan
- Exhaust
- Speedway block hugger headers with Stebro twin-pipe exhaust
- Transmission
- T5 5-speed with Tilton hydraulic throw-out bearing
- Rear axle
- Good Parts Nissan/Infiniti Q45 limited-slip differential, 3.7:1 gear ratio, CV jointed axles
- Frame
- Completely rewelded with added diagonal braces; fabricated motor mounts locating the engine lower and further back
- Front suspension
- 300 lbs/inch springs, 7/8" ADDCO sway bar, four Borgeson steering U-joints to clear the engine
- Rear suspension
- 375 lbs/inch springs, telescopic shock absorbers on fabricated brackets
- Brakes
- Stock Triumph TR-6 master cylinder and booster; Wilwood 4-pot front calipers with solid rotors; aluminum rear drums
- Wheels
- Konig Rewind aluminum wheels, 16"x7", zero offset
- Tyres
- General Altimax RT, 215x16
- Interior
- Biscuit colored vinyl interior
- Electrical
- Battery and fuel pump relocated to the trunk
- Paint
- DuPont Centari acrylic enamel, "Pitch Black" color code 99A
- Weight
- Ford 302 V8 with aluminum heads and 5-speed gearbox weighed 24 lbs less than the original Triumph engine and transmission combination
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.
Shop suggestions are being prepared. The owner's parts list is available below.
Engine 5
- Ford 302cid V8 (rebuilt)
Base engine for the conversion, rebuilt before installation
- Edelbrock E-Street aluminum cylinder headsEdelbrock
Fitted to the 302 to reduce weight and improve flow
- Edelbrock camshaftEdelbrock
Matched to the head and intake combination
- Roller lifters
Used with the Edelbrock camshaft
- Ford Racing valve coversFord Racing
Fitted to the 302 V8
Fuel & Ignition 4
- Edelbrock Performer 289 low-rise intake manifoldEdelbrock
Leaves about one inch of clearance above the air cleaner
- Edelbrock 500cfm carburetorEdelbrock
Fitted to the Performer intake
- HEI distributor
Ignition system for the V8
- AC Delco 8mm silicone spark plug wiresAC Delco
Ignition wiring for the engine
Cooling 2
- 19x24 3-row cross-flow aluminum radiator
Sized to cool the V8 swap
- 16 inch Kenlowe electric fanKenlowe
Paired with the aluminum radiator
Gearbox & Drivetrain 4
- Ford T5 5-speed gearbox
Replaced the original transmission, relocated six inches rearward
- Tilton hydraulic throw-out bearingTilton
Used with the T5 clutch actuation
- Good Parts Nissan/Infiniti Q45 limited slip differentialGood Parts
Rear differential giving a 3.7:1 ratio
- CV jointed axles
Used with the Q45 differential
Suspension & Steering 5
- 300 lbs/inch front springs
Front suspension springs for the V8 conversion
- ADDCO 7/8 inch sway barADDCO
Mounted on a fabricated plate bolted to the bumper supports
- Borgeson steering U-joints (four)Borgeson
Route the steering column around the V8 engine
- 375 lbs/inch rear springs
Rear suspension springs for the conversion
- Telescopic shock absorbers
Fitted on custom fabricated steel tube brackets
Brakes 2
- Wilwood 4-piston front calipersWilwood
Fitted to Triumph spindles with solid rotors and upgraded wheel studs
- Aluminum finned (Alfin) rear drumsGood Parts
Mounted on Good Parts hubs with 3/8 inch studs
Wheels & Tyres 2
- Konig Rewind aluminum wheelsKonig
16x7 inch wheels with zero offset
- General Altimax RT tyresGeneral
215x16 tyres fitted to the Konig wheels
Body & Trim 2
- Custom fiberglass transmission tunnel cover
Molded by the owner over a built-up cardboard/foam pattern using foil, resin and fiberglass cloth
- DuPont Centari acrylic enamel paintDuPont
Pitch Black finish, color code 99A
Interior 2
- Auto Meter electronic tachometer mechanismAuto Meter
Replaced the mechanical tach mechanism inside the rebuilt gauge
- TR-3 chrome gauge bezels
Used with domed glass crystals on the rebuilt TR-6 gauges
Other 2
- Speedway block hugger headersSpeedway
Exhaust headers fitted close to the block for clearance
- Stebro twin-pipe exhaustStebro
Exhaust system fitted behind the headers
Photos
All 29 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
Engine and drivetrain choice
The stock TR-6 engine was replaced with a rebuilt Ford 302 V8 fitted with Edelbrock aluminum heads, a matching camshaft and roller lifters, a low-rise intake and carburetor, and an HEI distributor. Power went through a T5 five-speed gearbox with a hydraulic throw-out bearing to a Nissan/Infiniti Q45 limited-slip differential with CV-jointed axles, chosen for strength and availability.
Frame and engine placement
The chassis was completely rewelded with added diagonal bracing for stiffness. Custom motor mounts placed the Ford V8 lower and further back in the chassis than many other TR-6 V8 conversions, improving weight distribution while leaving room for accessories.
Steering and cooling around the engine
Because the V8 sits close to the steering rack, four Borgeson U-joints were used to route the steering column around the engine block, and the owner reports the steering still feels light. A large three-row aluminum radiator and electric fan were fitted to manage cooling for the V8.
Suspension and brakes
Front springs and a thicker anti-roll bar were fitted along with Wilwood four-piston calipers on the Triumph spindles and upgraded wheel studs. At the rear, aluminum finned drums were mounted on Good Parts hubs, with heavier springs and shock mounts fabricated to carry the telescopic shocks.
Transmission tunnel and firewall
The stock tunnel and firewall were cut and reframed to fit the larger T5 gearbox, which sits six inches further back than stock. A new 16-gauge steel tunnel was welded in, and the shifter opening in the aluminum H-form member was relocated lower and rearward to match.
Custom fiberglass transmission cover
Rather than reuse the stock cardboard cover, Derek built up the original with foam and plastic to form a mold, then laid aluminum foil over it followed by three layers of resin and fiberglass cloth. Once cured, the new lightweight fiberglass tunnel cover was pulled free of the mold.
Interior and electrical
The dashboard was ground down, refinished with the owner's own graining and coated in Varathane, then fitted with rebuilt TR-6 gauges under TR-3 chrome bezels and domed glass. The mechanical tachometer was converted to electronic using an Auto Meter mechanism. The interior was trimmed in biscuit-colored vinyl, and the battery and fuel pump were relocated to the trunk.
Exterior and finish
New bumpers were mounted lower and closer to the body for a cleaner look, with the parking light holes filled in to suit. The car rolls on Konig Rewind aluminum wheels with General Altimax RT tires, finished in DuPont Centari acrylic enamel in Pitch Black. The whole project took about eleven months to complete.
A summary in our own words. The full account, with all its detail, is the owner's: read it at britishv8.org ↗
Worth knowing
- Placing the V8 lower and further back than typical conversions helps weight distribution.
- Routing steering around a V8 with extra U-joints can still preserve light steering feel.
- Building a fiberglass tunnel cover over a built-up cardboard mold gives a lightweight custom fit.
- Relocating the battery and fuel pump to the trunk frees up space for the larger drivetrain.
- Choosing a common differential like the Nissan/Infiniti Q45 unit can simplify sourcing a strong limited-slip rear end.