TUNING THE AUSTIN SEVEN
(Continued from the November issue, in which the Modifications made to the sia odard model since its introduction in 1922 were described and the ” Brooklands and standard 1925 sports models were mentioned.) F. WILLIAMS
F. Williams, to whom we are indebted for the accompanying notes on Tuning the Austin Seven, specialises in Austin Seven tuning and modification at Messrs. AutoConversions, 2, Belton Road, Willesden, N.W.2 ; telephone Willesden 3180.
While at the Austin Motor Co. Ltd., Mr. Williams saw possibilities of developing special editions of the famous ” Seven.” He spent twelve months on his own, experimenting with chassis-lowering and the construction of a body based on that of the J2 M.G. He then went into business, building the W-Special Austin Seven, supplying a considerable number of these special cars, including two rather extraspecial ones to the order of K. C. Jarvis. Williams can supply the J2 body shell in ash, with dummy rear tank, panelled in steel and with beaded edge, ready for fitting, for £10, and can build the complete body on to any Austin Seven chassis for £45, naturally charging extra for any special equipment a client may
specify. The photograph shows the modern lines of the W-Special, which has full all-weather equipment and a 3 ft. bonnet. Williams is a keen sprint enthusiast and builds himself a new racing job every
year. This year he ran at Prescott, Dancer’s End and Morkyate, using an unblown side-valve Austin Seven with ” Nippy ” carburation layout, coil ignition and an ingenious two-pipe exhaust system to avoid the bottle-neck at the silencer which a three-branch system sometimes involves. This Austin revved to 6,500 r.p.m. and gained two second places at Dancer’s End, beating ” Ulster •’ Austins and J2 M.G. Midgets. Williams is now building a single-seater Austin for next year, which has a Cozette compressor and carburetter, ” Ulster ” copperised head and standard gasket, pump-cooling, and three-branch external exhaust system. Much of the engine is T. T. ” Ulster ” and the body started life on a racing Maserati. Austin enthusiasts should pay an early visit to Belton Road, where there is much to interest them. Gordon England was producing his 75 m.p.h. semi-racing ” Brooklands ” model at this time, with the approval of the Austin Co., and also his ” Cup ” two-seater, built of fabric on his patented construction he also used for saloons, and ha v iitg the spare wheel hOused in a flat-backed tail. Another special job of this period was the ” Bnghley ” twoseater, with boat-type tail and flaired Wings, made by liVilSona Motors Ltd., of Eccleston Street, and priced at £175. The chassis was quite standard. Vet another special job was the B.C. two-seater, made by Boyd-Carpenter Ltd., of Kil burn. The cars had o.h.v. heads of L.A.P. manufacture, the push-rods running up the existing Valve guides, and the old. ports blanked off. Other modifications included enlarged ports, polished passages, special Claudel-Hobson carburetter, lowered springs, extra spring leaves, lowered and extended steering and remote gear-control. The body had a long tail and cycle wings and in 1930 the price was 97 10s., or 1,25 extra with o,h.v. head. Tested by Moron SPonr (September 1930), the speeds were 50 to 55 m.p.h. on second and 71 m.p.h. on top. Many other specialised sports jobs have been made, notably the Swallow twoseaters and saloons the Arrow, Stadium etc. In 1930 the Austin Co. introduced their own new sports model, based on the cars which were to rim so suecessfullv at Brooklands, Ulster and Le Mans. -These cars had special pistons, con rods and crankshaft, ratios of 4.9, 7.0 and 12.5 to 1, and the ” l’ister ” racing tail body, lowered frame with ” Ulstz-r ” front axle and outside exhaust. The unblown model was capable of 60 to 65 m.p.h. and cost z:185, and the supercharged job, with small Roots-blower, gear-driven on the near side of the engine and magneto ignition, did 80 to 85 m.p.h., and cost £225. The spare wheel was carried in the tail. For 1932 these cars were discontinued. The next sports job produced by Austins was the ” 65,” which gave 23 b.h.p. at 4,800 r.p.m. and cost £152 in 1934. It had the short tail, cut-away two-seater body with doors. In 193-5 this model became known as the “Speedy,” with ratios of 5.25, 7.82, 12.39 and 20.48 to 1. These cars had the ” Ulster ” type front axle. For 1935 the “Nippy ” was introduced, in appearance like the ” Speedy,” but with ratios of 5.6, 8.38, 13.3 and 21.9 to 1 and giving :20 b.h.p. at 4,000 r.p.m. For 1936 only the ” Nippy ” was offered, with threebearing crankshaft and Girling brakes, the Speed being 65 m.p.h. and the prke 042. For 1938 the sports model was discontinued, and Cooper’s of Putney purchased nineteen ” Nippy” bodies, which are offered at );20 each, ready to tit, with screen, hood, side-screens, wiper, battery box, wiring, etc. Both ” Speedy” and ” Nippy” models had Zenith downdraught carburetter, highcompression ratio, special valves and highlift camshaft. The ” Nippy ” had slightly modified oilways, but the ” Speedy ” had 50 lb. feed to big-ends and camshaft. Both had 1 gallon ribbed sumps, machined con-rods with oil leads to the gudgeon-pins, and Burgess silencers. The ” Speedy ” had a V-screen, the ” Nippy ” a flat screen and a hinged rear panel concealing the spare wheel, in place
of the pointed tail. The ” Nippy ” weighed 9 cwt. 3 qr. 14 lb. and had 3.50″ X 19″ tyres. It did 13.44 m.p.h. at 1,000 r.p.m. in top gear as against 14.4 m.p.h. of the normal 1936-7 cars.
As a comparison, the standard chassis of 1937-8 had ratios of 5.25, 8.73, 13.85 and 22.94 to 1 and the two-seater weighed 10 cwt. 7 lb. There are important differences in the valve tinting of the various sports models. The supercharged ” Ulster” Model had the inlet opening T.D.c., a 2200 on inlet and 240° exhaust period and an overlap of 15°. The lift was approximately .030″ less than with other camshafts. The anblown ” Ulster ” had the inlet opening 10° before T.D.C., a 2500 inlet and 2600 exhaust period and 30° overlap. The ” 65″ or ” Speedy” had the inlet opening on T.D.C., a 2400 inlet and 2500 exhaust period and 20° overlap. The two latter camshafts cannot be used in the standard engine on account of the size of centre bearings and the fan pulley cannot be used with the blown ” Ulster “
camshaft. So mach for variations in the different production models—fuller information on this subject and on care and maintenance of ordinary models up to 1937 will be found in that excellent work of reference : “The Book of the Austin Seven” by Gordon G. Goodwin (Sir Isaac Pitman & Sons, 2/6). We come now to a consideration of moderate tuning, to improve acceleration and to increase road speed to 60 m.p.h.,
or for sprint work. For the following information we are indebted to F. Williams of Auto-Conversions, who has tuned a large number of Austin Seven engines of all types. If speeds of over 60 to 05 m.p.h. or 5,500 r.p.m. are contemplated it is essential to use a 1930 type engine with the larger crankshaft. The 1930 crankshaft can be used in the older magneto ignition engines but this entails changing the back-main bearing. The older crank is liable to snap across the journals if overstressed. The Austin Seven is very sensitive to carbur4tion alterations. The Gordon England “Cup” ” models had a special manifold with short riser, and horizontal section well clear of the exhaust manifold ; it was tubular, with buffer-ends. The existing Zenith layout may be discarded and a 26 mm. or 80 mm. S.U. used. with this manifold. An S.U. from an old Morris Minor is 22 mm. and will not suit. Even better results can be obtained by reversing the Gordon England manifold so that the flange is uppermost, when a 26 mm. or 30 nun. downdraught S.U. can be bolted in place. If this is done at least two gallons of fuel must be kept in dashboard tanks to ensure adequate feed, or the tank may be placed under pressure. With this arrangement engine speed can be in
creased to 6,500 r.p.m. The best carburetter setting must be found by experiment, using standard S.U. needles, and raising and lowering the needle to enrich or weaken the mixture in the ordinary way. The inlet ports in the block can be opened up by ilf” all round, which means lots of elbow grease. Care should be taken to line up the inlet-pipe flanges with the ports. The exhaust ports are, in any case, larger than the inlets and there is little point in enlarging them, but the three-branch ” Ulster” manifold, or the three-branch external exhaust system made up by Auto-Conversions, effects considerable improvement, in conjunction with the ” Ulster ” silencer. Another line of attack is to scrap the inlet manifold and bolt two 26 mm. horizontal S.U. carburetters directly to the inlet ports. If this is done, a
balance pipe must be used on the engine side of the throttles. Twin carburetters give an excellent surge of power, but render the engine delicate to control for road motoring. Yet another line of attack is to replace the older exhaust manifold with the 19384 type manifold and the horizontal carburetter mounting described earlier on, while the standard 1933-6 manifolds together will give excellent results, especially if the Zenith carburetter is replaced by an S.U. The maximum speed of the Austin Seven engine is limited by valve bounce to 5,000 to 5,500 r.p.m. This can be overcome by fitting Terry’s double aero valve springs, with considerable improvement in speed on the indirect gears. If single Terry aero springs are used 45 to 50 m.p.h. in top is possible before power-loss from bounce is experienced, and with
double Terry springs the valves seat properly up to 05 m.p.h. Before doing any further tuning a very careful examination should be made of the main and big-end bearings. If the crankshaft journals have worn oval regrinding is essential, and the big-end bearings should be taken up, or re-metalled if oval or scored. The ball and roller main bearings should be replaced if badly worn—we have heard of Hoffman and Marks bearings being bought for 5/each for this purpose. It is important to remember that the engine is a high speed unit and to replace worn parts and assemble to approved clearances before attempting to push up speed or power output. Worn bearings cause rough running and loss of efficiency and are liable
to sudden failure and worn valve tappets set up a bad rattle—the cure is to grind the heads flush. Lighter pistons are of advantage and Mr. Williams recommends those sup plied by Specialoid, which have dome heads and are made of an alloy which wears extremely well. Three piston rings
per piston are advisable, including the scraper ring. The use of 7A# rings or 1 rum. rings reduces piston friction. So far as cylinder heads are concerned, Mr. /Williams favours the ” Ulster ” cast iron head, which has a machined pocket over the valves, on Whatmough principles. This head gives a compression ratio of 8 to 1 with the standard C of A gasket, and for sprint work it may be used with a IV Klingerit gasket, which
gives a ratio of 8.5 to 1. No detonation takes place if this head is properly copperised—but avoid firms which offer to do the job cheaply and merely copperplate. Aluminium heads sometimes distort and they strip their plug threads. The Alta heads with inclined plugs is quite good otherwise ; while the writer has run some 3,000 miles with a Silvertop alloy head, in which the plugs are over the inlet valves. A standard gasket was used and no trouble was experienced, but oil loss occurred via the holding-down studs and the engine would not take any ad
vance. Performance appeared to be improved and quicker warming up resulted. For increased performance the ignition may be given more advance. The standard magneto timing allows the points to commence breaking at T.D.C. With the hand control in the fully-retarded position the venier-coupling may be advanced half to one notch, after which the driver must use the ignition control. It should be two-thirds up the quadrant at speeds below 30 m.p.h. and fully advanced thereafter. With coil ignition it is permissible to increase the advance by 1 inch on the flywheel rim over the standard setting (or a total of 21 in. to 3 in. before the T.D.C. position), timing with
the hand control at full retard. Final adjustments should be made at the distributor in the ordinary way, to suit different fuels and individual requirements, remembering that energetic use should now he made of the hand-lever. Weight can be removed from the fly
to the extent of 1 to lu lb. If more than this is removed, slow-speed.
running will suffer. Metal should be taken from the back face or bevel, leaving a lip of 116 in. For sprint work, if more than 65 m.p.h. is craved, the standard camshaft should be replaced by the unblown ” Ulster ” camshaft 011 magneto-ignition engines or by a special high-lift camshaft having provision for a rev, counter drive, on
coil-ignition units. This necessitates fitting different tappets and tappet. gear. The ” Ulster ” camshaft is still available from Austins, priced at Z4 2 6, and ” Nippy ” camshafts cost about £6 18 0. Tulip valves are worth fitting, but must be of standard length. Messrs. Auto-Conversions can supply suitable tulip valves. It should be noted that “
Ulster” tulip valves have longer stems than those used for the ” Nippy” engine, and do not interchange. The standard lubrication system comprises a vane-pump forcing oil to the camshaft bearings and out of two jets into oilways in the crankshaft webs, from whence centifugal force feeds the big. ends. The tappets and roller main bearings are mist-fed. This seemingly crude system functions remarkably well and there is no point in increasing pressure beyond the normal 2 to 5 lb. per square inch, even with a tuned engine, though this can be done, by adjustment of the crankcase ball-valve, by fitting a stronger spring or an additional spring made from half a standard spring. For racing work it is highly desirable to use the “
Ulster” or ” Speedy ” crankshaft (which is apparently fitted now to a lot of “Nippy ” models) which has 50 lb. delivery to the big-ends via the nose of the shaft, which is hollow, ensuring an even oil supply to all bearings. If the standard crankcase is somewhat cleaned up internally it will accommodate the pressure-fed crankshaft, but the work of conversion is considerable.
The standard sump holds only half a gallon of oil, and for fast long-distance journeys it is advisable to use the 1 gallon cast-iron sump, which Austin can supply for about 22/-. Cooling can be improved by increasing the header tank size to twice standard capacity or, less effectively, by substituting the ” Ulster” fan-blade for the standard fan. For racing, pump cooling is advisable and Messrs. Auto-Conversions make a special pump winch they fit to those W-Specials exported to warm
climates. A drive can be obtained from the dynamo pinion or, if preferred, the pump layout used for the supercharged “Ulster “job may be employed. Mr. Williams recommends K.L.G. 848 plugs for road work, with the engine tuned in accordance with the foregoing
notes. K.L.G. themselves specify M 30 plugs for the standard Austin Seven engine, M So plugs for use with an alloy head and. compression-ratio of about 7 to 1, and M 80 plugs for ” Ulster ” or highly tuned engines. The later models had a compression ratio of about 6 to 1 as standard. Aero Shell, Castrol XXL and Essolube Racer are recommended lubricants for the sports engines. The correct tappet clearances for sports engines are : inlet .004″ to .006″ and exhaust .006′ to .008″. The recommended carburetter settings for the Zenith carburetters are :—” Nippy ” (downdraught) : choke 21, main jet 85, compensator 55, slow-runner 60, capacity tube 2, and progression jet 90 ; for the ” Speedy ” (downdraught) : choke 25, main jet 120, compensator 40, slowrunner 60, capacity tube 2 and progression jet 90, and for the standard engine (late-type, horizontal) : choke 17, main jet 57, compensator 50, slow-runner 60, capacity tube 2, and progression jet 100. The Austin Seven seldom gives less than 40 m.p.g. and sometimes as much as 50 m.p.g. The writer has obtained 41 m.p.g. from a coupe with Gordon England manifold and updraught Zenith carburetter, Silvertop alloy head and blown ” Ulster” camshaft, with the
engine in none too good condition. A quite standard 1935 engine with four speed gearbox and the 5.25 to 1 rear axle in an early frame will give 50 m.p.h. cruising and is suitable for trials work ; to fit the engine it is necessary to shorten the propeller-shaft, which a firm like Laystall Ltd. will do for about 30/-.
It is important not to overgear a tuned engine by fitting big tyres. Always use the 5,25 axle, or the 5.6 axle ratio if available. If using the older 4.9 to 1 axle, replace 19 x 5.50tyres with special wheels and 17″ x4.0″ covers. There are various ways of lowering the Austin Seven chassis. The “
Ulster” front axle may be fitted, or the special axle, of rather greater upsweep, which is supplied by Messrs. AutoConversions. This axle costs £4 2 6, or L3 2 6 if the existing axle is given in part exchange, and includes long front links to lower the radius arms 2 in. etc. Attempts to mount the spring on extended brackets invariably result in rolling and yawing. The spring can be placed below the axle for special racing assemblies. The rear quarter-elliptic springs can be placed on top of, instead of inside, the frame side members, but this results in lack of rigidity and there is grave risk of the springs swinging sideways.. A better plan is to have the leaves flattened. If done by a reliable spring-maker break
ages should not be experienced. New wooden discs in the Austin shock-absorbers and binding the springs with window cord will materially improve road-holding. Standard shock-absorbers suit the dropped ” Ulster ” axle. The Austin Co. rake their Steering in three ways : sports, semi-sports and standard. To convert to sports rake use a metal (not wooden) wedge under the Steering box, bolted to the chassis. The normal clip at the top of the column will still fit. As an alteration of i” at the box drops the wheel 1.1″ the wedge is tricky to make. Messrs. Auto-Conversions can supply correctly drilled metal wedges at 7/6 each. Raked steering feels more • positive than that of the Standard car and at first the driver tends to oversteer, but this tendency will soon be over
come. As the standard ratio gives 1} turns lock to lock, a higher ratio is unnecessary. Braking efficiencycan be improved by doubling the length of the brake-cant levers. Messrs. Auto-Conversions supply these lengthened arms and can modify the layout on any Austin Seven model at a price of 25/-. They also manufacture a Bowdenex Cable system of actuation, which does away with the compensator for the front wheels, providing equal braking on each wheel winch the old layout does not, with individual adjustment, and allowing the front brakes to
lead over those at the back. This Bowdenex system costs f,3 complete, or ac4 fitted, and looks thoroughly businesslike. The application of supercharge to the Austin Seven engine is rather Outside the scope of this article, as it verges on timing for racing results, but in any case it is inadvisable to go beyond a boost of 5 lb. per square inch for road or ordinary competition work. The Austin Roots blower is not very efficient but is worth using if in good order, likewise the Cozette vane-blower. Both were used as
standard on the ” Ulster” jobs. The Centric No. 4 vane-blower is excellent, also the Arnott, and when supercharging the standard C of A gasket is advised..
A very simple remote gear control can be made by cutting down a four-speed Austin Seven gear-lever and welding the ball-gate thereon, bolting the assembly to the propeller-shaft tunnel and connecting to a quarter of the actual lever by yoke-ends and rod. If welding is out of the question a yoke may be bolted to the tunnel. Old Arid l motor-cycle gearrods and yoke-ends Suit the job admirably. Reverting to the engine, coil ignition fades badly at 6,000 r.p.m. Williams recommends using a Lucas high-speed. coil, which is satisfactory up to 9,000
r.p.m. A less expensive improvement is the use of an American 6 volt replacement coil, as supplied for cars like the Packard, etc. For speeds over 70 to 75 m.p.h. a Scintilla ” Vertex” magneto can beneficially replace the coil system. Incidentally, fitting an ignition booster saves trouble with the ignition condenser, which, of course, is applicable to all makes of car. In conclusion, the writer craves indulgence for any errors or omissions in these notes, pleading that the field is a very wide one. One must congratulate the Austin Motor Co. Ltd., on putting such good material into a little car which dealt the cyclecar proper its deathblow sixteen long years ago. The design is still fundamentally the same and stands a remarkable lot of amateur tuning trickery. Its very size makes the Austin Seven an amusing engine to tune for increased performance, and somehow this car has a fascination peculiar to itself, which is not shared by other babies. It seems that a club for keen owners of standard and converted sports “
Sevens” Might go down very well and do good work—if sufficient people are interested we believe we can put them onto a sound secretary and trials organiser.