Nerus Engineering J.C. Conversion
November 1964
Nerus Engineering: twin SU carburettors, special manifold and a straight through silencer
May 1964

The Imp Site

Nerus Engineering

Like everybody else, Nerus' development engineer Frank Webb expected the Imp engine to be improvable. Some research indicated that solving the Imp's breathing problems would be gratifying.

Nerus came up with four different stages of tuning for sporty Imp-owners, the hottest of these was refered to as the J.C. conversion. It is claimed to give 42% power increase over standard. But it isn't temperamental or intractable.
Cost: £91 -> total cost for the Nerus Imp: £623. (£55 more than a Mini Cooper at £568)

A year after the Imp first rolled out of the factory, several firms had tried their hand at tuning the Imp. The Nerus Imp with the J.C. conversion was the first to impress.

Frank Webb specialized in solving top-end breathing problems, and the standard Imp's breathing was constricted. The improvements were mainly in carburetion and top-end.

SU 1,25 +  Nerus inlet manifold

The manual choke operates through a Bowden cable. The control is on the wheel arch at the driver's right knee.

Stick-on Nerus badges were optional. One in the middle on the lip of the bootlid and the other on the engine compartment lid, below the register number.


Acceleration times (sec.):
m.p.h. gear ratio: 1.14 to 1 5.70 to 1 8.91 to 1 16.91 to 1
10 - 30 
20 - 40
30 - 50
40 - 60
50 - 70
60 - 80
-.- (15.1)
15.2 (14.2)
13.2 (14.1)
14.0 (19.3)
17.2 (23.0)
18.4    (-.-)
9.6  (8.9)
8.1  (8.6)
7.6  (9.9)
9.6 (14.6)
14.0    (-.-)
-.-    (-.-)
5.0  (5.3)
4.7  (6.3)
-.-    (-.-)
-.-    (-.-)
-.-    (-.-)
-.-    (-.-)
-.-    (-.-)
-.-    (-.-)
-.-    (-.-)
-.-    (-.-)
-.-    (-.-)
-.-    (-.-)



Nerus Hillman Imp
tested by Practical Motorist

(a standard Hillman Imp,
tested in Autocar of 3 May 1963)
[standard Hillman Imp,
tested in Practical Motorist 1963]

(997 cc Mini-Cooper)

From rest thru gearsAutocar May 1964Practical Motorist Nov 1964
to 30 mph   4.5 sec.   (5.4)   4.1 sec.   [6.1]
to 40 mph   6.9 sec.   (9.1)   (7.4) 6.9 sec.   [10.0]
to 50 mph 11.8 sec. (14.7) (12.6) 10.4 sec.   [15.6]
to 60 mph 16.5 sec. (23.7) (18.0) 15.4 sec.   [23.4]
to 70 mph 26.2 sec. (38.4)   22.2 sec.   [-.-]
to 80 mph 34.9 sec.    (-.-)   35.8 sec.   [-.-]

For gear changes 7,000 was used as the limit, although in first and second gear 8,000 rpm could be displayed on the the rev counter easily. A matter of improved breathing.


Maximum speed on gears
Top (Mean)   
85.6 [78]    139.9
3rd    72 (71)  74 [60]    116 (114)
2nd    46 (46)  47 [40]    74 (74)
1st    28 (25)  25 [22]    45 (40)


The standing quarter-mile (402 meters): 20.0 sec. (21.8); 19.7 sec., doing 67mph at end.

Overall fuel consumption for 235 miles (378km): 35.2 mpg. (8.0 litres/ 100km) (38.1 mpg.; or 7.4 litres/ 100km)
At a road average of 30mph: 51.2 mpg.; [51.0]
At a road average of 50mph: 30.1 mpg; [36.5]

    Nerus Hillman Imp
Looks like it acquired a dent during the Practical Motorist performance car test
Nerus Hillman Imp

Nerus Hillman Imp 875 c.c. : improving the performance of popular cars. - Autocar 1964, May 8. - p.908-909
Testing 7760 FN
Reprinted in TSB 081. - p.18-19

The Nerus Hillman Imp : performance car test. - Practical Motorist 1964, November. - p.311
Testing 7760 FN
Reprinted in TSB 081. - p.23

At the time (1964) the address was:
Nerus Engineering Co.
Rye, Sussex
And the conversion was available from
R.J.V. Ltd.
165a Westbourne Grove
London W 11

Racing-Car Show 1965

The catalogue and guide to the 6th annual Racing-Car Show lists Nerus Engineering Co. Ltd. as exhibitor of Stand No. 3

Location: in West Hall, Olympia, London
Date: January 22nd - 30th 1965
Org.: British Racing & Sports Car Club

Nerus Engineering Co. Limited

Rye, Sussex.

To the inhabitants of the small Sussex town of Rye the names Frank Webb and Nerus Engineering mean the conveniently placed and immaculately kept premises on the main through-road, but to the majority of motor sporting enthusiasts, the workshops at Rye signify the home of the foremost cylinder head conversion specialists in the country.

Under the direction of Frank Webb, formerly Chief Assistant to cylinder head and air-flow specialist Harry Weslake and previously engaged in making motor racing history in the early 50's as Team Chief of the H.W.M. Formula 2 Grand Prix cars, the company has, for many years concentrated on the requirements of motor manufacturers, racing teams and comenrcial organisations [...].

Now concerned with producing cylinder head conversions for the everyday motorist in addition to their Competition Department, Nerus specialise in conversions which offer not only increased power output, but give reduced fuel consumption without additional strain or the need for constant attention to the engine.

These conversions are available for all makes of cars and are offered fully assembled, in 3 stages of tune:

Nerus Stage I Conversion

Using standard parts only and providing improved middle range torque, this conversion offers a marked increase in smoothness and fuel economy.

Nerus Stage II Conversion

Incorporating larger inlet valves and stronger valve springs for increased r.p.m. and including further modification to the combustion chambers, the Stage II conversion allows for higher performance, whilst still retaining overall fuel economy.

Nerus Stage III Conversion

Including larger inlet and exhaust valves, double valve springs and fully balanced combustion chambers, this conversion allows for maximum peformance and b.h.p. to be obtained yet remains compeletely flexible throughout its range. Designed to allow for an extremely large margin of potential power increase when allied to larger carburettors, sport camshafts and fully tuned exhaust systems, all Stage III heads are check tested on the Air-flow plant before leaving the factory. On all stages of tune, the combustion chambers are fully balanced for improved smoothness and torque at low revs, a feature of all Nerus conversions.


Also on show will be the popular Nerus conversion for the Hillman Imp which gives a 42 per cent power increase together with a range of cylinder heads, carburettors, camshafts and exhaust systems plus a 2-litre Elva-B.M.W. racig engine, which has been loaned by Elva Cars (1961) Limited, and with which Tony Lanfranchi became Autosport Champion for 1964 in one of the works cars.

All Nerus conversions are available from distributors throughout the U.K., all of whom specialise in cylinder head conversions.

In attendance: Frank Webb and Conolly Tuke.


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