V8 Saloon Weber Carbs

V8 Saloon Weber Carbs Description

In production: 1973 - 1978

Chassis numbers: V8/11002/RCA - V8/12000/LCAV, then V8/12010/RCAS - V8/12031/RCAS excluding 11001

- V8 Vantage chassis numbers are also within the AM V8 series

- 12001 - 9 not used to avoid confusion with Lagonda V8

In August, 1973 a “NEW Aston Martin V8” was unveiled to the press at the West End showrooms of AM dealer, Hexagon Motors. This car had the important change away from the Bosch fuel injection system to four, twin-choke downdraught Weber carburettors topped by a new airbox, fed by a pair of 76 mm diameter air pipes drawing air from the front of the engine compartment. This in turn required a noticeably taller bonnet scoop to clear the airbox and carburettors. Whilst the fuel injection system was initially fitted to the V8 in the belief it would be easier to comply with strict US emission control regulations, as these became tougher year on year, thoughts changed and carburettors were felt to be a better bet in the long run.

With the Weber carburettor set-up, performance of the V8 at low engine speeds became notably smoother, with greater flexibility. The bulge on the bonnet was noticeably larger extending all the way back to the trailing edge. At the opposite end of the car, the extractor ventilation louvres behind the rear window were replaced by a shallow lip adjacent to the boot lid which allowed more efficient extraction of stale air from the cabin.

Several other modifications were introduced: water, oil and automatic transmission cooling were all improved; optional back axle ratios of 3.54:1 and 3.07:1 were offered for manual and automatic transmissions respectively; a new insulating material called Industrialite was used for the bulkhead and under the bonnet. Detailed improvements inside the car were revised front seats, the passenger door could be locked electrically from a switch by the driver’s side, new push-pull switches at the bottom of the centre console, a rotary dial on the facia for the lights, wiper control from a stalk on the steering column, fuses in a new panel below the glove box and a larger, centrally located, ash tray and cigar lighter. The instrument dials which previously had been in a line became staggered. With the deletion of the fuel injection, the fuel surge tank was no longer needed which increased space in the boot for luggage. Under the bonnet, the finish of the cam covers was changed to silver.

Rex Woodgate came up with an interesting development in the USA. Rex had been 'Mr Aston Martin' in the States for many years, as General Manager of AML Inc., the US branch of the UK parent company in King of Prussia near Philadelphia. He had been having a difficult time with very patchy sales since the introduction of the DBS V8. The problem had been that the DBS V8 was unveiled in September 1969 in the UK and naturally, US buyers were drawn to the new car which had cut across sales of the six cylinder DBS which still satisfied the US Federal exhaust requirements. Yet AML Inc. were only clear to sell the Federalized DBS V8 from September 1971 to the end of that year. Rex, worried that even with the new Weber set-up, the V8 engine would not meet the stringent 1974 regulations, and mindful that the US market was important, had received permission to develop his own system that would be acceptable.  In conjunction with a Californian turbo-charging specialist, AK Miller, they took only four weeks to develop an effective system using a Garrett exhaust driven centrifugal supercharger, drawing through a four-barrel (four-choke) Rochester carburettor.

However, when the Weber Company heard of this successful development, they were spurred into action and were able to design a system to satisfy the upcoming 1974 regulations. Indeed they went on to design a system to satisfy the even tighter 1975 regulations, which included an exhaust catalytic converter necessitating a change to lead-free petrol. The use of regular leaded petrol would have caused irreparable to the catalytic converter. In addition, the compression ratio was reduced to 8.3:1 and a belt driven air pump, later increased to two, forced clean air into the exhaust system. These US Federal or emission control engines received an LFA or LFM suffix for automatics and manuals respectively and, although there was an initial heavy drop in power, further development saw the power creep up to something in the region of 275 bhp. The lead-free carburettor engine is easy to identify with its chunky ribbed alloy sealed airbox linked to the evaporative loss system with carbon canisters. Thus, after a 50,000 mile test, the V8 received its US Federal Certification on 29th October 1974. This would have unlocked the sale of a decent number of cars to the USA except that time and cash had almost run dry. The effect of the 1973 Arab–Israeli War and the subsequent massive increase in fuel costs plus the unfavourable economic climate, meant that demand for expensive thirsty luxury sports cars was shrinking fast.

By September, 1974, it was clear that the company was in severe financial difficulties. It was publically forced into administration and production was stopped on the last day of December 1974, although the service and parts departments remained in business. An offer for AML by a pair of businessmen, American Peter Sprague and Canadian George Minden both Club Members, was accepted on June 27th 1975. Shortly they were to be joined in the new company, Aston Martin Lagonda (1975) Ltd by Britons, Alan Curtis and Denis Flather, also Aston Martin enthusiasts. (See AM, Vol. 18 No. 67, 178, p.46).

V8 Saloon Weber Carbs Updates

The first update following the restart of production was an engine modification designed to liberate a little more power, reduce fuel consumption and reduce noise, known as ‘Stage 1’ tune or sometimes ‘S-spec’, announced in June 1977. Stage 1 tune was an intermediate step between the previous regular V540 and ‘Stage 2’ ‘Vantage’ tune which chiefly involved new camshafts with a polynomial profile and the fitting of a ‘Vantage’ exhaust. Other small detailed changes included more modern looking black bezels replacing chrome around instrument dials, the deletion of the chrome trim on the rain gutters and the fitting of Koni dampers

V8 Saloon Weber Carbs Derivatives

Canadian S Specification ‘Vantage’ AM V8

A unique and often misunderstood sub-model was made especially for the Canadian market. The Canadian S specification ‘Vantage’ AM V8 had the external appearance of the flip tail Vantage but with an engine to Stage 1 'S' specification. As this car does not have a V at the end of the chassis number, it cannot truthfully be described as a Vantage, which is perhaps a little odd. Odd particularly as the US market received visually similar cars, correctly described as cosmetic Vantages, with a V in the chassis number but with the less powerful, catalysed, lead-free LFM engine. In total, there were eight Canadian ‘S’ specification ‘Vantage’ AM V8s built, all left hand drive and four of each in manual and automatic. Most of these cars have subsequently been modified to full Vantage engine specification.

Despite a year and a half hiatus in production, the AM V8s built between 1973 and 1978 were the most numerous variant with a total of 970 examples, 576 RHD (at least 134 manuals and 438 automatics) and 394 LHD, (124 manual, 270 automatic).

V8 Saloon Weber Carbs Specification

Body / Coachwork
Two-door 2+2 coupe
Steel platform chassis with handcrafted aluminium alloy body panels
Dual 7'' quartz-halogen headlamps
Interior
Connolly or Bridge of Weir leather interior
Coolaire air-conditioning system
Bucket seats with tilting squabs to allow access to the rear seats
Radiomobile radio-stereo eight-track cartridge tape player, four speakers, electric aerial
Optional Phillips AM/FM radio cassette player or Phillips AM/FM radio cassette recorder. Later Blaupunkt Berlin AM/FM radio cassette recorder
Engine
Front-mounted all-alloy 90° V8, 5,340 cc, two valves per cylinder, twin overhead camshafts per bank. Engine number prefix V540/
Bore 100 mm. Stroke 85 mm. Compression ratio 9.0:1 (8.3:1 Emission Control LFM & LFA)
Four Weber 42 DCNF downdraught carburettors. Fuel supplied by SU AUF 412 electric pump
Maximum power: not quoted at the time but now believed to be between 280 bhp and 300 bhp. (230 +/- bhp Emission Control LFM & LFA). 'S' specification engine believed to be 306 bhp @ 6,000 rpm
Maximum torque: not quoted at the time but now believed to be 320 lb.ft @ 3,000 rpm
Air injection system: AC Delco air pumps from 1977
Twin catalytic convertors on Emission Control LFM & LFA
Ignition system: Lucas 'OPUS' Mk 2 electronic
Transmission
Automatic: Chrysler TorqueFlite three-speed automatic
Manual: five-speed ZF. Hydraulically operated 10½" Borg and Beck single dry-plate diaphragm clutch. Additional cost option from 1975
Final drive: Salisbury hypoid bevel with Powr-Lok limited slip differential
Final drive ratio: 3.31:1 (manual), 3.54:1 (optional and North America specification), 3.07:1 (automatic)
Steering
Power-assisted Adwest rack and pinion, 2.9 turns lock to lock. Turning circle 11.58 metres
Wheels and Tyres
Bolt-on, five-stud, GKN Kent 15 x 7'' light alloy wheels
Avon GR70 VR15 radial low profile tyres
Suspension
Front: independent, unequal transverse wishbones, coil springs and co-axial telescopic Koni shock absorbers with an anti-roll bar
Rear: De Dion axle tube located by parallel trailing links and a Watts linkage. Coil springs and double-acting piston shock absorbers
Brakes
Front: Girling, ventilated discs; 10.75" diameter
Rear: Girling, inboard ventilated steel discs, 10.38'' diameter
Tandem master cylinders and dual vacuum servo assistance
Dimensions
Length: 4,660 mm
Width: 1,829 mm
Height: 1,327 mm
Kerb weight: 1,727 kg
Wheelbase: 2,610 mm
Front track: 1,499 mm
Rear track: 1,499 mm
Fuel tank capacity: 95.4 litres, 114 litres from October 1977
Performance
Maximum speed: 146 mph (automatic), 155 mph (manual), 135 mph (LFM specification)
Acceleration: 0-60 mph 6.2 seconds (automatic), 5.7 seconds (manual), 7.7 seconds (LFM specification)
Prices, (including UK purchase tax/VAT and car tax where applicable)
September 1973: £9,593
August 1974: £11,349
1975: £12,795
1976: £15,600
May 1977: £16,600, (USA, January 1977: $33,950)
October 1977: £19,000, (USA, July 1977: $37,500)
January 1978: USA over $40,000

V8 Saloon Weber Carbs Number Guide

For the first time since the war, chassis and engine numbers directly corresponded, so that the engine in V8/11002/RCA is V/540/1002. This continued all the way through to the end of V8 production in 2000. The prefix of V8/ continued with the exception of cars for the Japanese market up to 1976 which confusingly continued with the DBSV8/ prefix. A source of further confusion to this day is that from 1976, Japanese market cars had the letter ‘J’ instead of the first ‘1’ in the chassis number, such as V8/J1496/LCA. Japanese cars from 1976 with the V8/J**** chassis number were also fitted with the LFA or LFM lead-free engine instead of the earlier /EE emission control engine.

Yet another cause for confusion, with the AM V8 from 1973, with the final ‘C’ in the chassis number suffix which indicated ‘Cosmic Fire’ paint, a then new paint process with a metallic flake suspended in the paint.

The introduction of the ‘Stage 1’ engine was signalled by the suffix “S” to both the chassis number (thus V8/11647/RACS the first series production example, after 11613 and 11631 and to the engine V/540/1647/S).

Chassis numbers from 12001 to 12009 were not used for the AM V8 so as to avoid confusion with the earlier Lagonda V8.

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