Riley Riviera & Silhouette

An original report from the late 1950s,

first published in 'The Motor':

Three-Stage Improvement of 4/Sixty Eight from Salisbury

In these days when cars tend to lack individuality, and improved performance kits are popular, there should be a healthy demand for new cars offered for sale in improved form. Purchase tax is not payable on the conversion, under the theory that the car is sold first and converted afterwards, while in practice the buyer is not deprived of the car while the work is carried out on it. Entirely new in this category is the Riley Riviera, a modified version of the Riley 4/68, and it is offered with sixteen changes, in three stages as listed below.

The car tried had the complete stage C conversion, and all the alterations listed proved to be really worthwhile and to have been thoroughly and efficiently carried out. There is nothing makeshift or haphazard in any part of the conversion, and in fact only knowledge of the basic car enables one to tell what has and has not been changed.

This is particularly true of the substantial redesign of the tail end of the car. The tail fins are cut along the crown, and then moulded over the excess cut away, so that the rear wing line follows the falling line of the rubbing strip. Redesigned tail lamps are blended carefully with the new wing shape, and neither externally nor from within the luggage locker is there any evidence to suggest that the car has not left the factory in this shape. On the model tried the finish had been resprayed in one shade of royal blue, and although car appearance must always remain a matter for personal opinion, all who saw the car agreed that, particularly with the embellishment of wire wheels, the Riviera was vastly improved in comparison with the standard 4/68.

Cost new in standard form, £725; with purchase tax, £1,028.

The three stages of build for the Riviera are as follows:


Conversion cost £100

Total cost £1,128

MG MGA engine

Recessed fog and spot lamps

Altered rear fins

Handbrake warning light

Front seats from Wolseley 15/60

Vanity mirror


Conversion cost £200

Total cost £1,228

All A changes, plus

Disc brakes (front) and Mot-a-vac servo

Wire wheels

Headlamp flasher

Dunlop Duraband tyres (or Pirelli Cinturas at £4 extra)


Conversion cost £271

Total cost £1,299

All A and B changes, plus

H.C. pistons and engine tuning

HMV radio

Electric aerial

Rear-window demister

Noise insulation

Servais silencer

At the front, the auxiliary lamps are neatly recessed into the otherwise bare panel to either side of the radiator grille, in similar fashion to the Wolseley 6/99, and they are mounted on rigid brackets underneath the bonnet.

Inside the car a handbrake warning light is installed on the facia, and a vanity mirror is fitted to the left sun visor. The main change to the Riviera is, of course, that the basic 1,489cc engine is lifted out and replaced by a 1,588cc MGA unit, complete with clutch. If the C conversion is specified, the ports of the engine are matched with the manifold, and competition connecting rods and pistons giving a compression ratio of 9.2 to 1 (instead of the standard 8.3 to 1) are fitted.

100mph on a Slight Downgrade

In this form the car is unexpectedly lively, and offers a really useful improvement of performance, as shown in the table overleaf. In particular, the acceleration above 80mph is specially creditable, and although the gearing (at 16.7mph per 1,000rpm) is not high, the engine as installed in the Riviera was exceptionally sweet and free from vibration, and cruising at up to 90mph was possible. At a true 100mph, which the Riviera would achieve on a slight downgrade, engine rpm are 6,000. An appreciable reduction in noise level is achieved by the sound damping included in the stage C conversion.

The only alteration whose value is arguable is the replacement of the Riley bucket seats with the divided bench seats from the Wolseley 15/60. The Wolseley seats are certainly more softly sprung, but offer less lateral support than those of the Riley; but there is the advantage that a third person can be seated in the front of the Riviera, which is not possible in comfort with the basic car.

In the stage B conversion, of course, the main change is the improvement of the brakes. At the front, the complete hub and disc brake units from the Austin-Healey 3000 are fitted, while the rear brakes are fitted with harder linings. A Mot-a-vac servo unit is installed under the bonnet, which compensates for the inherent low-speed deadness of the disc brake, and on the road the response to the brake pedal was found to be reassuringly powerful, although at low speeds the brakes are less sensitive than the normal drum brakes of the 4/68. The main improvement is naturally at the higher speeds, and in B and C stages the car certainly has adequate braking to cope with the extra performance available. The headlamp flasher is of the type fitted to Jaguar Mk II saloons.

With stage C the engine tuning already described is the main improvement, but the radio installation is first class, and with the useful gimmicks of remote-control electric aerial and rear-window fan demister, this, too, has a lot to offer. The Servais silencer provided in this stage of the conversion gives a crisp but not obtrusive crackle to the exhaust note.

Of course, one may always say that "they should change this" or "they should concentrate on that," and it is perhaps unfortunate that the steering and road holding remain far from ideal. On all conversions the suspension is lowered by _in and with this and the addition of the Pirelli Cintura tyres adhesion on slippery roads is much improved. But there is still excessive roll on corners leading to a roll oversteer condition, and the excessively light steering is imprecise.

Nevertheless, the Riviera as offered is a useful step forward in a market which ­ as we have commented recently ­ is badly catered for at present. The conversions are carried out by Wessex Motors Ltd., New Street, Salisbury, Wiltshire, telephone: Salisbury 3275/6. Extensive use of BMC components for the conversions means that the guarantee is not invalidated. We are grateful to Mr.D.N.Dixon, who provided the car for test.

(The Riley Silhouette was the Wessex Motors version of the later Riley 4/Seventy Two)


PERFORMANCE (Conversion C)

(Figures in brackets are those of the Riley 4 Sixty Eight in unmodified form)

Acceleration from rest through gears to:

30mph 4.6 sec (5.8)

40mph 6.7 sec (9.1)

50mph 10.1 sec (13.9)

60mph 14.9 sec (20.5)

70mph 20.3 sec (34.0)

80mph 29.7 sec (-)

90mph 44.2 sec (-)

Standing quarter-mile 19.5 sec (22.0)

Acceleration in Gears (sec):

MPH Top Third Second

10-30 - 7.2 (8.2) 4.3 (5.1)

20-40 10.5 (11.9) 7.6 (8.2) 4.2 (5.8)

30-50 10.5 (13.1) 6.5 (9.4) -

40-60 12.1 (13.3) 8.4 (11.6) -

50-70 12.9 (21.8) 9.4 (-) -

60-80 15.0 (-) - -

70-90 22.8 (-) - -

Maximum Speeds on Gears:


Top (mean) 95.3 (86.5)

(best) 97 (91)

Third 73 (67)

Second 44 (41)

First 26 (25)

Brakes (at 30mph in neutral):

Pedal load in lb Retardation Equiv. stopping distance

25 0.29g (0.21) 104 (144)

50 0.72g (0.43) 40 (70)

75 0.80g (0.68) 36 (44)

Fuel Consumption:

Overall, 22.2mpg (23.3).

Range 19-28mpg (20-30)