Triumph TR7, TR7V8 & TR8 Information

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TR7: Create a TR8 PDF Print E-mail
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Sunday, 19 September 2010 17:58

The TR7, which finally went out of production over five years ago, was originally designed to accommodate the 3500cc Rover engine so that the car could be sold on the US market as the TR8.
We in Britain were left with the car in its limp-wristed 2litre form and very few TR8’s were ever sold in the UK; the only glimpses of a TR8 that most people in Britain ever had was when they made a brief appearance on the international rally circuit. But that does not mean that the gutsy TR8 is beyond the reach of us Brits.
The TR7’s 1998cc engine was a combination of the Dolomite Sprint’s iron block and the Dolomite 1850’s eight valve alloy head. Not only was this a problematic unit, it did not provide much in the way of ‘poke’.
This unit can be tuned to a certain degree but for little money, the lusty Rover V8 can be accommodated easily beneath the bonnet with only a few simple modifications. And that not only brings quicker performance but also brings the smooth low down torque characteristic of this classic engine.
Even by slotting in a standard second-hand V8 SD1 engine into the TR7 you can transform the car, giving 130mph performance and sub-eight second 0 to 60 times. But surprisingly, there are masses of tuning and handling parts available to further improve V8-equipped TR7’s.
You can also take advantage of all the development work that has been carried out on the engine on other cars too. The capacity can be increased to 3.9, 4.2 or even 5.1 litres...imagine a 5100cc TR7!

Why the TR7?

The TR7 may not seem like the ideal candidate for a tuning project.
For most of its life, the car has attracted tags such as 'hairdresser's car' or 'wimp mobile' - you know the sort of comment, along the lines of the abuse that is often hurled at the Spitfire.
And also in a few years time, the TR7 should be just about becoming recognised as a classic.
The beauty of the car at the moment is that fixed head versions can be picked up for as little as £500, even less if you are prepared to put up with a rotted example.
Then there's the convertible. A beautiful car. The last in a line of affordable British convertibles, which can now be bought for as little as £1500.

The conversion

So what do you need for the conversion and what will it cost you?
Well to pick up a few tips and to look at the work involved, we visited S & S Preparations, of Ramsbottom in Lancashire, who carry out all kinds of conversions on TR7's from simply slotting in a second hand V8 right up to £6,000 worth of mods to create a real road racer.
"Creating TR8's is taking off in a big way and is becoming big business for us. Some of our customers have picked up a TR7 for as little as £500. Anextra outlay of a few hundred quid will give them a good-looking GTi beater...and it's British", says Steve Wilcox, one half of the S & S duo.
"A TR8 is much more distinctive than a boring hot hatch, far more modern than the old Escort Mk 1's and a t the moment it's a pretty rare beast too - no wonder it's becoming such a popular road racer", he added.
What is beautiful about the conversion is that the modifications required are minimal. The 5-speed gearbox on the TR7 is the Rover SD1 'box anyway, the only change needed is to swap the TR7 gearbox's bellhousing to one which accommodates the new engine.
The rear axle on the standard car is fully capable of taking the increased power output too.
There is adequate space beneath the bonnet for the engine, again because the car was designed to take the lump anyway. There are slight clearance problems with the bonnet line when SU carburettors are used but this can be solved by fitting a modified crossmember. S & S have their own made up for this job.
Another way round this clearance problem is to fit the Holley four barrel carburettor and corresponding K & N air filter which will give you a 20 bhp power increase.
A new radiator and electric cooling fan is also required because of clearance problems lengthways. The electric fan is mounted in front of the radiator and blows air through.

Handling and suspension

If you are looking for a soft ride, then the TR7's standard suspension will be fine, but the car does tend to wallow a little when pushed on corners.
The ideal sports set-up, although you do lose something in terms of comfort, would be to uprate the inserts and fit either 25% uprated or 200lb rated coil springs in the MacPherson struts. At the rear, again either 25% uprated or 200lb rated coil springs would improve matters greatly, along with Spax gas adjustable shock absorbers.
Although we said the standard axle is capable of handling the power, you can make simple axle ratio swaps to up the car's top speed. The standard TR7 ratio is 3.9:1 and is geared for a 115mph top speed, a 3.45:1 axle ratio from the Rover 2.6 will give a 130mph top speed, while the 3.08:1 axle from the 3.5 Rover will give a 140mph top speed.
If you are determined to recreate the TR8 as best you can, it's worth noting that the TR8 stick-on decals and the genuine TR8 steering wheels are stil available through the Rover Group. Now and again, the more attractive American spec. bumpers come available through the same source too.

 

Exhausted

On the TR8, you can choose between two types of exhaust system.
One is a twin pipe system along the full length of the car. The other is a single pipe system. This involves joining the two sets of pipes half way down the length of the car.
We tried a car with a THREE INCH bore single pipe system and the noise was unbelievable!

 


Conversion choice

We asked S & S to suggest four different stages of tune ranging from a do-it-yourself basic conversion costing a few hundred pounds up to a complete £3,800 facelift giving 180bhp at the rear wheels.

Stage One

The first and least expensive stage would involve finding your own V8 unit and fitting the modified subframe, new engine mouting brackets and rubbers and a new radiator with mounts.
The TR8 brake kit with bigger discs, calipers and pads would be included, the TR8 cast exhaust maifolds with a twin pipe system in stainless steel, new choke and throttle cables, a new rev. counter, and electric fan, K & N air filter, complete wiring diagram, and an uprated oil pressure switch and spring.
From S & S, this kit would cost £825 and you could expect about 115bhp at the rear wheels.

Stage Two

The second stage suggested by S & S would involve having the stage one conversion work carried out by the company and again would involve a used Rover V8 SD1 engine painted to a specified colour.
In addition to the above, this would be supplied with SU carburettors with chromed dashpots, a bellhousing, an electronic ignition system, new coil, an anti-dive kit and polished rocker covers.
The rear suspension bushes would also be changed for the solid-type bush. To give you an idea of price, this conversion would cost about £1600. The power at the rear wheels would amount to around 120bhp. S & S offer a rebuilt Rover engine, with a 12 months guarantee, for an extra £800.

Stage Three

This is where it starts to get silly and although the price of this particular conversion starts to get silly too, it shows exactly what can be done.
So, we move on next to a fully rebuilt V8 with a Holley 390 carburettor, Offenhauser inlet manifold and 14 inch chrome air filter. On the suspension side, Spax gas adjustable shock absorbers would be fitted with 200lb rated springs all round.
This conversion would produce around 155bhp at the rear wheels, for around £3500 drive away, with an allowance for your old TR7 engine.

And there's more...

If you are already determined to get the most out of your Rover V8, you can go even further up the silly scale.
The stock V8 can be fitted with a high lift Kent H214 cam and 10.5:1 compression ratio pistons which would give 180bhp at the rear wheels. And even then, the engine can be bored out to 3.9 or 4.2 litres and by fitting a Chevy crankshaft on the latter, the capacity of the engine can be increased to 5.1 litres giving a whopping 300bhp at the rear wheels.

 


Extract taken from the magazine 'Car & Car Conversions' dated around 1986.