Impressions of the A.C. Ace fitted with a Rudd modified Ford Zephyr engine
Introduced in 1953 the A.C. Ace was the first post-war British sports car to feature all-independent suspension and apart from the recently introduced Jaguar E-type and one or two specialised G.T. cars remains as the only fully independently sprung sports cars produced by a British manufacturer, which seems to indicate that the British motor industry has progressed very little in eight years and as our pictures show it is still one of the best-looking sports cars on the road. Designed mainly by John Tojeiro the Ace features a chassis based on two large diameter tubes with welded-up sub frames front and rear to take the transverse leaf spring and wishbone suspension, with steeply inclined Armstrong telescopic dampers. The engine fitted was the 2-litre, single overhead camshaft 6-cylinder A.C. engine which has now been in production for 40 years and gives 102 b.h.p. in its latest form. However. the car really came into prominence when the 6-cylinder Bristol engine giving power outputs of up to 120 b.h.p. became available in 1956. With this engine, which was already well known to racing drivers, the Ace began a long run of competition successes especially in the United States where it is almost always a class winner.
Recently another engine change has been made in the Ace because the Bristol engine is in rather short supply. The Bristol engines will be reserved for fitting in the Greyhound model and through an arrangement with K. N. Rudd (Engineers) Ltd., of Worthing, Ace and Aceca models will be assembled at the Thames Ditton factory except for engines and gearboxes and then transported to Worthing for the fitting of a Ford Zephyr engine. At first sight this seems to be a retrograde step, discarding the overhead camshaft A.C. engine and the Bristol with its ingenious valve gear but the 2-1/2-litre Zephyr engine produces 90 b.h.p. at 4,400 r.p.m. in standard form against the 105 b.h.p. at 4,700 r.p.m. of the Bristol unit and more important produces maximum torque of 133 lb./ft. at 2,000 r.p.m. compared with the 129 lb./ft. at 3,000 r.p.m. of the Bristol unit, and of course is much cheaper. The basic price of the Ace will now be £1,197 plus £499 17s. 6d. p.t., making £1,696 17s. 6d., and the Aceca will be £1,482 plus £618 12s. 6d. p.t., a total of £2,100 2s. 6d., a saving of around £500 on the Bristol-engined cars.
The Ace can be obtained with the standard engine but Rudds anticipate that most owners will require the engine to be tuned and have accordingly devised three stages of tune for the rugged Zephyr unit. These are listed in the data panel.
Stage I: Modified Ford cylinder head, opened and polished ports, larger inlet and exhaust valves. Triple inlet manifold with three H4 1-1/2-in. S.U. carburetters. 120 b.h.p. at 5,000 r.p.m. £75.
Stage II: As Stage I with lightweight pistons. 125 b.h.p. at 5,500 r.p.m. £100.
Stage III: Light alloy 6-port Rubery Owen cylinder head, triple inlet manifold and three H6 S.U. car buretters. 140 b.h.p. at 5,000 r.p.m. £160.
Stage IV: As Stage III with lightweight pistons. 155 b.h.p. at 5,500 r.p.m. £215
Stage V: As Stage IV with three Weber DCOE2 carburetters, alloy push-rods. 170 b.h.p. £225.
It can be seen, therefore, that a performance far in excess of that provided by the Bristol engine can be obtained for a considerably lower expenditure, and to sample that performance Ken Rudd loaned us his prototype car which is fitted with the Stage IV conversion.
First, we learned from Mr. Rudd, who has been responsible for much A.C. development in the past through his racing activities, that the fitting of the Zephyr engine has not caused too many problems as it is only 40 lb. heavier than the Bristol unit. For safety’s sake an extra leaf has been inserted in the front transverse spring and the heavy-duty dampers which were previously optional extras are now included in the standard specification. The gearbox used with the Ford installation is of Moss Gears’ manufacture which is mated to the Ford engine with a special bell-housing. The gearbox ratios are 1st 2.97 : 1; 2nd 1.745 : 1; 3rd 1.205 : 1; 4th 1 : 1; Reverse 2.97 : 1; and the final drive ratio in the test car was 3.9 : 1 although optional ratios of 3.64 and 4.30 are available. The test car was also fitted with the optionally available Laycock de Normanville overdrive, operating on third and top gears which, as we discovered during the test, is well worth the cost.
Entry into the Ace is about on a par with most sports cars – awkward, and getting out is hampered by the handbrake lever which is mounted to the right of the driving seat and usually manages to travel up the left trouser leg; however, one only carries out these operations once on each journey so unless one happened to be a commercial traveller little annoyance can be caused. A centrally-mounted handbrake is available at no extra cost. The well padded bucket seats give excellent lateral support but the backrests are a little too upright for those drivers who prefer the now popular semi-reclining position, but they hold the driver firmly when cornering fast. Wedges are available from the manufacturers to give the necessary rake.
Pedal positions are good but most drivers would prefer an organ-type throttle pedal to facilitate heel-and-toe gear changes. On the test car the optionally available wood-rimmed steering wheel was fitted, the column of which is adjustable both for reach and rake. Tall drivers might find the cockpit a little cramped but they can splay their legs out and reach a very comfortable position and obtain extra bracing from the cockpit side and engine bulkhead.
Instrumentation is very complete, with tachometer and speedometer on either side of the steering column, and to the left of the speedometer are gauges for fuel contents, oil pressure, water temperature, ammeter and a clock. A combined ignition and headlamps switch is fitted with positions for side and main beams, combined with a floor dipper switch, and a separate starter button is fitted. The choke knob is on the engine bulkhead. In front of the driver a dynamo charge warning light is flanked by two direction indicator warning lights, for which the self-cancelling switch is on the steering wheel boss, as is the horn button. To the extreme right of the facia, level with the steering wheel rim is the overdrive switch which can be operated by the index finger without removing the right hand from the wheel. The instrumentation is completed by a windscreen washers button, the jets for which are angled to hit the correct spot on the screen when travelling at speed; unfortunately we operated them with the hood down at a service station so that the driver and a surprised attendant were given a shower bath.
For the stowing of odds and ends there is a good, lockable glove locker and pockets in both doors. The boot, although shallow because the spare wheel is mounted flat on the floor, is surprisingly commodious and will take the holiday luggage of two people without much trouble.
However, the Ace is not the sort of car in which one desires to sit and admire the instruments, however comprehensive the layout may be, and driving away from Worthing along A24 it soon became clear that the excellent torque of the Zephyr engine had endowed the Ace with great tractability and a fascinating top gear performance; in fact, it was possible to potter along at 30 m.p.h. in overdrive top and accelerate smoothly away up to a comfortable 90 m.p.h. cruising speed. The noise level has been kept to a minimum with the use of twin silencers and the only intrusion comes from some carburetter roar, but the A.C. with the Zephyr engine is much quieter than many much slower sports cars. Carburetter air silencers can be specified instead of ram tubes at no extra cost.
Using 5,500 r.p.m. as a maximum (the tachometer is red-lined at 5,800 to 6,000 r.p.m.) the performance is extremely satisfying
Average of four runs:
0-50 … 7.6 sec.
0-60 … 10.0 sec.
0-70 … 12.9 sec.
0-80 …16.8 sec.
Standing start 1/4-mile: 16.8 sec.
Maximum speed: 123.8 m.p.h. (see text)
Speeds in gears: 1st, 37 m.p.h.; 2nd, 62 m.p.h.; 3rd, 90 m.p.h.; 4th, 107 m.p.h.
Overall fuel consumption: 22.4 m.p.g.
Price: £1,197 plus £499 17s. 6d. purchase tax; total, £1,696 17s. 6d.
Extras: Overdrive, £93 10s.; hard-top, £85; heater/demister, £21 15s.; bumpers, £15; wood-rimmed steering wheel, £12 10s. Tuning as per list.
as the accompanying acceleration data suggests; the figures, which are the average of four two-way runs are about the same as these for the Ace-Bristol with D-type competition engine, and of course the Zephyr engine has at least 20 b.h.p. more to come. Our best one-way acceleration times with hood down, two passengers and 6 gallons of fuel were 0-50 6.9 sec.; 0-60 9.6 sec.; 0-70 12.2 sec.; 0-80 15.6 sec.; and a standing start 1/4-mile in 16.3 sec. A flying 1/4-mile was covered at an indicated 5,500 r.p.m. in top gear for an average speed of 107 m.p.h. and in overdrive top with the hood down the car covered the same distance at 123.8 m.p.h. at which speed the tachometer showed 4,800 r.p.m. and refused to go any further. With the hood -erected Ken Rudd has been timed at 130 m.p.h. The optional extra hard-top would probably extract another 1or 2 m.p.h. from the Ace, although for normal motoring the hood is perfectly acceptable having an excellent fixing method at the front and being free from drumming. Vision is rather restricted with the hood erect and it was stowed in the boot for the duration of our test. There is a good deal of turbulence without the hood and no doubt an aerodynamicist could explain why a well pulled down “flat hat” would always fly off at exactly 80 m.p.h.
Although the Ace has independent suspension all round the ride is very firm, abetted no doubt by the Michelin “X” tyres which are now almost considered as part of the design, although Ken Rudd may experiment with Dunlop RS5s. Bumps are transmitted to the occupants rather more frequently than one would wish with i.r.s. and on bad secondary roads some body shake is evident with one or two rattles making themselves known, although the light-alloy bodywork on a tubular steel frame showed no sign of warping and all panels were an excellent fit. No doubt the non-racing owner would probably prefer to specify softer dampers and/or spring settings. With the settings of the test car the handling is superb and a driver new to the car has difficulty in judging just where the limit of adhesion comes and fast main road curves can be taken at full throttle with a very reassuring “running on rails” feeling. Towards the limit oversteer warns of impending breakaway but lifting of the throttle foot restores the status quo.
With only two turns lock-to-lock the steering wheel calls for little movement in making corrections and the Ace can be tweaked through traffic gaps very easily. Naturally the steering calls for some effort but this remains constant, being no worse at parking speeds than when travelling fast, the fact that the Michelin “X” tyres were inflated to 28 lb. all round no doubt helping somewhat.
Girling 11-3/4 in. disc brakes are now standard fittings on the front wheels and combined with 11-in. Alfin drums at the rear provide the A.C. with almost unbeatable braking characteristics; the pedal pressure required is not unduly high and the car always pulls up all-square from high speeds with no sign of fade. Although the handbrake operates on the rear drums it would not hold the car on a steep gradient and a gear was always engaged when the car was parked on a hill.
he Moss gearbox seemed able to cope with the torque of the Zephyr unit although some whine was evident in 3rd gear. Swift changes defeat the synchomesh but in ordinary road motoring this would hardly worry the driver as most other cars are soon left behind without the need to constantly “swop cogs,” and on winding roads, 3rd, overdrive 3rd and top gears are all that is required to keep up very high average speeds. The value of overdrive is once again demonstrated as one can save the engine whilst still maintaining high speeds. Rudds may experiment with lower axle ratios so that the Ace can reach peak revs. in overdrive top, which should give the car a very useable 130 m.p.h. maximum speed.
Fuel consumption over our 1,000-mile test worked out to a commendable 22.4 m.p.g. and only under performance testing conditions did the consumption fall below 20 m.p.g. With a 33-gallon tank the Ace has a range of nearly 300 miles. No oil or water was consumed although the engine ran quite hot during our period of ownership which coincided with a minor heat wave.
The extreme simplicity of the design of the A.C. makes this a fairly easy car to maintain and now that the design incorporates an engine from the great Ford empire, service for this unit will be available all over the world as well as being considerably cheaper to overhaul or replace. Moreover, the adoption of the Zephyr engine endows the A.C. Ace with a more attractive performance, especially on the road and when in racing tune should go so quickly that it stands a good chance of being banned from B.A.R.C. marque races! – M. L. T.