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Ken Morris's 1972 TR-6 V8 conversion

Ken Morris · 1972 Triumph TR-6

Triumph TR6

britishv8.orgas published in British V8 Newsletter, Volume XV Issue 1, April 2007

Read the full write-up at britishv8.org ↗

Photo: britishv8.org

Ken Morris's 1972 Triumph TR-6 rebuilt with a Chevy 350 V8

Ken Morris spent three years converting his 1972 TR-6 to run a GM crate 350 V8 backed by a Muncie four-speed, while reinforcing the chassis and rear suspension to handle the extra power. The write-up covers sourcing parts from a local scrap yard and specialty suppliers, custom steering column work, and the small snags left to sort out after completion. It is a useful reference for the fabrication and parts-sourcing side of a V8 swap rather than a polished, problem-free build.

Specs

As the owner states it.

Engine
Chevy 350 cid GM crate motor, stock cam
Intake
Edelbrock 2701 dual plane intake with Edelbrock 1406 Performer series carb
Cooling
19x27 inch aluminum crossflow radiator, custom built
Exhaust
2 inch system with twin Flowmaster Hushpower round mufflers
Transmission
Muncie M-21 close ratio 4-speed (1967), 11 inch clutch with Tilton hydraulic release bearing and 7/8 inch Tilton master cylinder, custom one piece driveshaft
Rear axle
Stock IRS system, plan to convert to a 9 inch axle later
Front suspension
Basically stock, new bushings, ball joints, tie rod ends, and heavy-duty coil springs
Rear suspension
Swing arm mounts replaced with 3 inch tubular steel, reinforced differential mounts, heavy-duty springs, tube shock conversion
Other chassis mods
Bracing around swing arm mounts, larger and thicker breast plate, frame reinforcement at motor mounts
Brakes
All stock for now, plan to do a Nissan dual piston conversion
Wheels/Tires
205/70R15 Pirelli tires
Body/Interior
Mostly stock body using parts from 1970 through 1976 model years, Mazda Miata seats modified to fit TR-6 seat rails and reupholstered locally
Electrical
AutoMeter Sport Comp gauges with electronic speedometer
Wiring
Harness supplied by Dan Masters, with phone consultation
Weight/Completion
Project started September 2003, completed September 2006
Miles driven
About 900 miles as of January 2007

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 1

  • Chevy 350 cid crate motorGM

    Stock cam, base engine for the V8 conversion

Fuel & Ignition 2

Cooling 1

  • 19x27 inch aluminum crossflow radiatorKarhouse (Bobby Kar)

    Custom built to cool the V8 swap

    In the shops
    Aluminum Radiator ↗Moss Motors – Triumph TR6/TR250· $259.31 USD
    Aluminum Radiator ↗Moss Motors – Triumph TR6/TR250· $259.31 USD
    Aluminum Radiator ↗Moss Motors – Triumph TR6/TR250· $356.75 USD

Gearbox & Drivetrain 4

Suspension & Steering 4

Wheels & Tyres 1

Body & Trim 1

  • Chrome plating serviceTri-City Plating

    Provided outstanding chrome finish with a lifetime warranty, though slow turnaround

Interior 1

Electrical 2

Other 1

  • Flowmaster Hushpower round mufflersFlowmaster

    Twin mufflers fitted to the 2 inch exhaust system

Photos

All 22 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.

Small Block Chevy EnginePhoto: britishv8.org
Chevy 350 enginePhoto: britishv8.org
Triumph TR-6 grillePhoto: britishv8.org
Pirelli tiresPhoto: britishv8.org
Triumph TR-6 hood with subtle racing stripesPhoto: britishv8.org
Triumph TR-6 tail lightsPhoto: britishv8.org
Reupholstered Miata seatsPhoto: britishv8.org
TR-6 BodyPhoto: britishv8.org
TR-6 Front SuspensionPhoto: britishv8.org
Restored Triumph TR-6 framePhoto: britishv8.org
Triumph TR-6 IFS - independent front suspensionPhoto: britishv8.org
Triumph TR-6 IRS - independent rear suspensionPhoto: britishv8.org
Test Fitting the Chevy Crate MotorPhoto: britishv8.org
Triumph TR-6 front cross bracePhoto: britishv8.org
Triumph TR-6 dashboard and instrument panelPhoto: britishv8.org
Advance Auto-Wire wiring kitPhoto: britishv8.org
Woodward Machine CorpPhoto: britishv8.org
Intermediate shaftPhoto: britishv8.org
Heim jointPhoto: britishv8.org
Steering Column Support Plate (on underside of fender)Photo: britishv8.org
Steering U-jointPhoto: britishv8.org
Donate Now!Photo: britishv8.org

How it was done

Starting the swap

Ken Morris began the conversion of his 1972 TR-6 in September 2003, replacing the original engine with a GM crate 350 V8 running a stock cam, topped with an Edelbrock dual plane intake and Performer carb. He paired the engine with a period Muncie M-21 close ratio four-speed gearbox, sourcing the gearbox parts and bellhousing from a supplier known as Kajun Jon.

Cooling and exhaust

To keep the V8 cool he had a custom aluminum crossflow radiator built locally by Karhouse. Exhaust gases exit through a 2 inch system fitted with twin Flowmaster Hushpower round mufflers, chosen for a quieter tone than typical V8 setups.

Driveline and clutch

An 11 inch clutch was fitted with a Tilton hydraulic release bearing and matching Tilton master cylinder, requiring modification of the actuator to work with the stock TR-6 clutch pedal. A custom one piece driveshaft connects the gearbox to the still-stock IRS rear end, with a 9 inch axle conversion planned for later.

Chassis reinforcement

To cope with the added power, Morris reinforced the rear suspension by replacing the swing arm mounts with 3 inch tubular steel and strengthening the differential mounts, along with heavy-duty springs and a tube shock conversion. He also added bracing around the swing arm mounts, built a thicker breast plate, and reinforced the frame at the motor mounts.

Suspension, brakes, and wheels

Front suspension remains largely stock, refreshed with new bushings, ball joints, tie rod ends, and heavy-duty coil springs. Brakes are still stock for now, with a Nissan dual piston conversion planned. The car rides on 205/70R15 Pirelli tires.

Body, interior, and electrical

The body stayed mostly stock, built up using parts spanning the 1970 to 1976 model years pulled from a scrap yard with over fifty TR-6s. Seats from a Mazda Miata were modified to fit the TR-6 seat rails and reupholstered by a local trim shop. Instrumentation uses AutoMeter Sport Comp gauges with an electronic speedometer, wired with a harness from Dan Masters.

Steering column work

Morris sourced steering column components, u-joints, and standoff supports from Woodward Machine Corp, who matched the exact TR-6 shaft spline count. He chose unplated units to save cost and painted them himself rather than paying for chrome.

Finishing up and remaining issues

The build was completed in September 2006 and had covered about 900 miles by January 2007. A few minor issues remained: an inaccurate electronic speedometer reading, a cooling fan that runs long after shutdown, and a clutch pedal that stiffens as operating temperature rises.

A summary in our own words. The full account, with all its detail, is the owner's: read it at britishv8.org ↗

Worth knowing

  • Sourcing body parts from a scrap yard with many donor TR-6s saved money on rare panels.
  • Matching exact spline counts (Woodward Machine steering shafts) avoids costly custom machining.
  • Quality chrome plating can take a very long turnaround, over three months in this case, but is worth the wait.
  • Electronic speedometers wired to a transmission pulse counter can give erroneous readings even after calibration.
  • Relocating the cooling fan sensor from block to radiator may be needed to stop the fan running too long after shutdown.
  • A clutch actuator built for a different pedal may need modification to fit the stock clutch pedal.

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