But not the buzzy sort. Nor was it a straightforward shoe-horn job for the
new MGB V8, as Philip Turner describes. Drawing by Lawrence Watts.
as published in British V8 Magazine, Volume XVI Issue 1, May 2008
Re-printed unedited by exclusive written permission of "Motor".
This article originally appeared in their issue for the week ending August 18, 1973.
1. twin electric fans, 2. ovens on exhaust manifold, 3. alternator, 4. larger radiator block
5. rear mounted twin SU carbs, 6. new gearbox, 7. three leaf rear springs,
8. new wheels with bigger tyres 9. adjustable headrest, 10. seat belt mounting.
One-time Mini racer Ken Costello has already shown that the Rover V8 can be installed in the MGB GT with most satisfactory results, for his conversions have been selling successfully for some time. It therefore comes as no surprise that MG themselves are now introducing a Rover V8-engined MGB to their range. In fact, the MG design team began work on this new addition as long ago as the summer of 1971, working to the brief that as few modifications as possible should be made to the main structure of the MGB in order to keep the price down.
The fruit of their labours is a new MGB V8 with 137 bhp under the bonnet instead of 95.
Possibly even more significant in everyday motoring is a massive increase in torque from
110 lb ft at 3000 rpm to 193 lb ft at 2900 rpm. Which means that the car can be whistled
along effortlessly with little or no recourse to the gearbox, or it can be fairly squirted
past other traffic when overtaking.
The Rover engine has been installed in the MGB engine bay very neatly, with no external power bulges to betray its presense. To this end, the two SU HIF6 horizontal integral float carburetters are mounted at the rear of the engine instead of in the centre of the vee. A special manifold has been devised to enable this revised mounting to be carried out and has the additional advantage of reducing temperature scatter between the cylinders compared with the original penthouse manifold.
To comply with the ECE 15 regulations on exhaust emission, especially when the engine is cold, bi-metal valves shut flaps in the air intakes so that the incoming air is warmed by diverting it through "ovens" on the exhaust manifolds which pre-heat the air. As soon as the engine reaches its normal working temperature, the flaps open and air is drawn direct from the atmosphere.
Emission regulations are also responsible for a reduction in the compression ratio from 10.5:1 to 8.25:1. Modifications to the engine engine to enable it to fit in the MG's engine bay include the use of an AC Delco alternator instead of a dynamo, and the installation of the oil filter in series with the oil cooler instead of in the base of the oil pump.
The exhaust manifolds have also been redesigned to suit the new installation and the two branches now merge into one in the region of the bell housing. This housing is also new for a new gearbox casing has been developed to enable the clutch diameter to be increased from 8" to 9.5" to cope with the increased torque. A further refinement is the use of a ball race for the clutch withdrawal race instead of a carbon brush.
The gearbox internals are mostly C-type with the intermediate ratios modified to bring them closer together. With a new final drive ratio of 3.07 instead of 3.91, the overall ratios are now 9.634, 6.059, 3.864, and 3.070 instead of 13.46, 8.48, 5.40, and 3.91. A Laycock overdrive operating only on top gear gives an overall ratio of 2.517 and is operated by a forward pull on the left-hand stalk which also controls the windscreen wipers and washers.
Few changes have been made to the body structure. The front bulkhead has been modified slightly to accomodate the rear ends of the cylinder heads, and slight depressions in the rear arch panels make room for the exhaust manifolds. The new and bigger radiator core with four rows of copper gills holds 16 pints of coolant instead of 9.5 and cooling is aided by two thermostatically controlled four-blade electric fans mounted in front of the radiator. The twin fan layout was adopted when supplementing the normal engine-driven fan to cure a heat soak problem in heavy traffic.
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The bolt-on front suspension member has been modified slightly to increase the ride height
by one inch and new front spring brackets for the rear suspension also have this effect.
Other modifications to the suspension include uprated coil springs at the front to take care
of the slight increase in weight on the front wheels. Although the basic V8 engine is 40 lb
lighter than the 1.8 litre four-cylinder unit, its total weight with all accessories - such
as the emission equipment and the bigger radiator block - is greater than that of the four,
so that the total weight of the car is up from 2260 lb to 2427 lb with a front rear weight
distribution of 49.4/50.6 instead of 47.8/52.2.
The rear suspension has received more extensive modifications. Instead of the semi-elliptic lead springs having one main leaf and five auxiliary leaves, the springs now have three main leaves. These are sufficiently stiff to prevent axle tramp when accelerating hard in the gears.
The rack and pinion steering gear has been modified slightly and is now mounted further forward relative to the front wheels in order to reduce the Ackerman effect. The primary shaft from the rack to the universal joint has been lengthened and the steering column has, therefore, shortened. It is also now collapsible.
To cope with the increased performance now available, the Lockheed brakes have been uprated; although the diameter of the front discs remains at 10.7" the width of the discs has been increased from 0.35" to 0.5". A servo is now fitted as standard instead of being an optional extra.
The Dunlop wheels are a distinctive feature of the new MG, with ventilated cast alloy centres riveted to chromed steel rims. They are said to be immensely strong, for the survived the standard 600,000 load reversal rig test and then carried on to complete three million reversals without failure.
Tyre size is up from the normal 165-14 of the four cylinder GT to 175-14. The slightly higher ride height and the bigger tyres combine to give the V8 a more massive look than its four cylinder relations from which in fact it differs very little externally. Apart from the new and attractive wheels the only outward indications of its extra performance are the V8 badges on the front grille, on the left front wing, and on the tail.
The fascia has been brought into line with United States Federal requirements, with 80mm
speedometer and rev counter in place of the 4" diameter gauges previously fitted. Otherwise
the well equipped interior with its deep bucket seats has not been modified, for it has
already been redesigned to meet both US Federal and European Economic Community regulations
on switches, padding and other safety points.
A full road test of the MG V8 will appear in next week's Motor.
|Cylinders||8||Type||4-speed manual with overdrive on top|
|Capacity||3528cc (215 cu in)||Clutch||9.5" sdp diaphragm spring|
|Bore/Stroke||88.9/71.12mm (3.5/2.8 in)||Internal ratios and mph per 1000 rpm|
|Cooling||Water||Overdrive||0.820 / 28.5|
|Block||Light alloy||Top||1.00 / 23.4|
|Valves||OHV||Third||1.259 / 18.6|
|Compression||8.25:1||Second||1.974 / 11.8|
|Carburetters||Two SU HIF6||First||3.138 / 7.4|
|Fuel pump||SU electric||Final Drive||3.070:1 hypoid|
|Max power||137 bhp (DIN) at 5000 rpm|
|Max torque||193 ft lb (DIN) at 2900 rpm||STEERING|
|Type||Rack and pinion|
|BODY / CHASSIS||Assistance||No|
|SUSPENSION||Type||Lockheed 10.7" discs / 10" drums|
|Front||Independent by upper/lower wishbones||Servo||Yes|
|coil springs, lever arm dampers,||Circuits||One|
|anti-roll bar.||Rear Valve||No|
|Rear||Live axle on semi-elliptic|
|leaf springs, lever arm dampers.||WHEELS|
|Type||5J cast alloy centers / steel rims|
|Tyres||175HR 14 radials|
|Wheelbase||7 ft 7 in (231 cm)||Width||5 ft 0 in (152 cm)|
|Front track||4 ft 1 in (124 cm)||Height||4 ft 2 in (127 cm)|
|Rear track||4 ft 1.5 in (124 cm)||Ground Clearance||4.25 in (10.8 cm)|
|Overall length||12 ft 10.25 in (393 cm)||Unladen Weight||2427 lb (1099 kg)|
|Base price||£1925||VAT tax||£208.54|
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