The F.W.D. Alvis, although not in very large production, achieved some notable competition successes and has many adherents, in spite of its rather complicated design. Not very much seems to be generally known about it, so this informative and enthusiastic article by R. Stelfox is of more than passing interest. He deals with the production-model supercharged 4-cylinder car. It is worth recalling that the first racing F.W.D. Alvis, although it looked like an experimental chassis, was actually a very advanced car, with deep duralumin side members united for about 3/4 of their length by a daralumin undertray. It had a 4-cylinder engine, the supercharger of which could be put into or out of action by the driver, and the car weighed 9 cwt. It was designed by W. M. Dunn and ran at Shelsley Walsh and in the 200-Mile Race in 1925. The production-model F.W.D. Alvis, which was the first four-wheeled British car with all wheels sprung independently and front-drive, made its debut at the 1926 Scottish Show. Straight-eight racing and T.T. versions were built later, but only the four-cylinder models, like Stelfox’s car, both blown and unblown, seem to have survived to the present day. -Ed.
As the F.W.D. Alvis is a little-known vintage type, I will give a brief description of its layout before going on to deal with my actual experiences with the car. Its components can be summed up in the one word — “massive.” The engine has a bore and stroke of 68 x 102 millimetres, giving a swept volume of 1,482 c.c.; the crankshaft, whose journals are 1 5/8-in. diameter, the one aft being 2 in., the centre 1 1/2 in., and the front 2 5/8 in. long, is supported in three bearings. It carries a pinion at the front, from which is driven the oil pump, mounted below the crankshaft, and feeding oil to the bearings by an entirely separate gallery. A chain of three idler gears takes the drive from the front end of the crankshaft to the single overhead camshaft; the second idler wheel also drives two gear wheels, one to the water pump and magneto at the off side, and one to the dynamo and supercharger mounted on the near side.
The valves are tulip-shaped, and each valve is fitted with two springs, held by the usual method of collar and split collets; they are unusual in that they are completely shrouded by a dashpot, which covers them and is kept in position by special wells cast in the cylinder head. The cams operate directly on the dashpots, depressing them as they rotate, and these, in their turn, operate on the top of the valve stems. In this way, all side thrust on the valves is eliminated, and tappet adjustment as such is unknown, as there are no tappets. Clearance is effected by the insertion of steel shims between the top of the valve and the underside of the dashpot, the shims being held in a small cup which fits over the valve-stem head.
Oil is led to the camshaft from a bypass in the pump, and is forced down the hollow shaft, in which each cam has a feed-hole drilled so that a constant supply of lubricant is led to the cam faces and dashpots, the surplus draining to the front of the cylinder head, and falling back to the sump via the camshaft-gear train.
The combustion chamber and ports are all carefully machined and polished, and, on my model, light-alloy con. rods are fitted, although I believe steel rods are the more common and really wear better, as the light-alloy tends to fatigue and the enthusiast may be met with the disconcerting sight of a con. rod coming through his crank case for a breath of air!
The pistons are slightly domed, and, in my case, fitted with three compression rings and one scraper ring, all above the gudgeon pin, which is of a sliding fit and 25/32 in. in diameter. The Alvis instruction book gives the pistons with one scraper and two compression rings, but the difference is accounted for in my bores having been taken out oversize by some previous owner.
The cylinder head, block, crankcase, and base chamber are separate units, the latter being an imposing aluminium casting that would do credit to a lorry, and housing two gallons of oil. The valve timing is: inlet opens 5° before T.D.C. and closes 55° after B.D.C.; exhaust opens 50° before B.D.C. and closes 10° after T.D.C. — very nearly a “square” timing. Ignition setting is 38.6° before T.D.C. on full advance, and the valve clearances between cam and dashpot are 6-thous. inlet and 12-thous. exhaust.
A large Roots supercharger looks after the induction side of things, sucking through a 40-mm. Solex carburetter with 26 choke, 135 main jet, and 60 pilot, and blowing through a “Y”-branch manifold directly into the block, being thankfully free of any hot spots (how I hate ’em!). The exhaust is rather quaint in that it comes from the head into a three-branch manifold, cylinders number 1 and 4 having an exit of their own, but numbers 2 and 3 having to share! The maximum blower boost is 5 lb. per sq. in., but the extraordinary things that go on inside an inlet manifold have to be seen to be believed; I nearly ran into a ‘bus the first time I fitted my gauge, I was so fascinated by seeing it jerk from a full 25 in. of suction as one lifted one’s foot. up to 5 lb. per sq. in. as one accelerated, and the apoplectic condition of the needle when it coped with a back-fire!
The drive is taken via a normal singleplate clutch, to a “crash-type” gearbox, and out through a standard differential, giving ratios of 4.81, 7.26. 10.10 and 15.44 to 1, with a reverse of 13.47 to 1. Engine, gearbox and differential are, of course, all one unit, and it is from now on that things become really unorthodox.
The front brakes are bolted directly to the differential housing, two short shafts about 9 in. long taking the drive from the differential to the brake drums, in whose centre is formed a universal-joint housing. Held away from the chassis by four transverse wishbone springs, is the front-wheel split hub-housing, which is attached top and bottom to the springs; inside this is held the interior spherical housing, extension of which forms the pivot, equivalent to the steering-head pin of the ordinary car, the lower extremity being attached to the steering arm. This housing also forms a universal joint, and is connected to the brake drums by a half-shaft, having a cross head at either end to which are fitted detachable balls; this permits the shaft to drive the hub from the brake drums with a full universal-joint action, and it also transmits the braking torque to the front wheels.
The rear wheels, too, are independently sprung being mounted on fore-and-aft radius arms which swing about the extreme rear of the chassis, the springs being reversed quarter-elliptics, and funnily enough, not provided with any form of damping.
Bodywork is fabric, and, in my case, is a two-seater with a sort of cubby hole in the duck’s back, in which a gibbering passenger may be deposited, though I have, on one classic occasion, carried five full-grown men, two in the duck’s back, and three of us in the front! Weather protection is a little scant, but sufficient for the enthusiast, and one gets accustomed to having only one door, and that at the passenger’s side. The windscreen is incredibly low, being a bare 6 in. in height, but the vision is surprisingly good, and one can see one’s near-side wing, in true vintage manner, despite the abnormally long bonnet, which has to house a gearbox and differential, in addition to the engine.
The gear lever and hand brake are on the right-hand side, giving a nice clean cockpit, and the instruments are adequate, magneto and dynamo switches being mounted in a panel to the right of the steering column (which is adjustable for rake) along with the headlamp switches. The centre panel houses speedometer and rev.-counter, oil and petrol gauges, and, on the left, the boost gauge is mounted separately, leaving just sufficient room for a small cubby hole in front of the passenger.
Coming now to my own personal experiences, the circumstances of my acquiring the Alvis were rather unusual. I had been a motor cyclist of some 8 years’ experience, my last mount being a “springer” Ariel “Four,” and I had had to get a car for business reasons, my first choice being a Riley Nine “Kestrel,” a rather pleasing little saloon, but tame after being used to 80 in third. After three months I had become bored with it. An advertisement, for a “Brooklands” Riley in a Glasgow paper lured me into town, and, after running it to earth only to discover it sold, I found as its stable companion the Alvis. The latter was examined as any enthusiast would look over an unusual car, and I returned home with no further thought of purchase, but, as the week-end passed, it kept coming back to my mind, again and again, until finally I just had to go back. A test run completed the thing, a deal was struck, and the Riley and Alvis changed hands. A lot of work needed doing, and one of the first things that happened was a rear-tyre burst which let the chassis sit down on the silencer, to its detriment and the consternation of the proud owner. A new set of tyres was acquired by rather dubious dealings with a local farmer who happened to have a trailer with similar wheels. The instruments were all in need of repair, and I was very pleased with myself by my efforts at constructing a blower gauge from an old Standard oil gauge which read up to 30 lb. per sq. in.; I knew the blower should manage 5 lb. per sq. in., and that atmospheric pressure was about 14.7 lb. per sq. in., so I dismantled the gauge and shortened the little arm connecting the needle quadrant and the link mechanism of the “C” tube, until the needle was reading 20 lb. per sq. in., instead of zero, and then gave the dial a new face, marking the positive position of the needle in lb. per sq. in. up to a maximum of 10, and the negative side in inches of mercury to it maximum of 30 in. The thing worked beautifully, much to my astonishment.
The car’s petrol consumption shook me rigid by turning out be an honest 10 m.p.g., and, incidentally, caught me napping (and minus petrol) in the middle of the Fintry Moors in the first days of my ownership. After all the tyro expects something a little better than 60 miles on 6 gallons from a 1 1/2-litre, blown or not. However, after going over the petrol supply lines and caulking up the worst leaks, I eventually got it to give me 25 m.p.g., with very modest driving methods, and 20 with fairly hectic ones, which isn’t too bad.
One point during the above bit of work, which indicates the highly efficient state of some of our garages just now, was borne out to me when I received my carburetter, after a supposedly complete overhaul. It was handed me as ready to bolt on, which I forthwith did, started up, and found that, although she could tick over and just run, she had no performance at all, and the chronic backfiring, at anything like a throttle opening, sounded like gunfire. As I, too, had carried out work on the engine, I humbly took for granted the fact that I had done something moronic, and proceeded to check everything I could think of, very nearly checking tyre pressures too, out of sheer desperation! I might add that I had blown through the carburetter before assembly, just in case some packing had got in, so I knew it was not choked. Finally, I came to the conclusion I was right, and it must be the carburetter, so I took it down, and, on unscrewing the little chimney affair that covers the main jet on the Solex, I discovered no main jet. As I had just paid some £8 10s. odd for the job, the things I called that garage were weird and wonderful.
I ran all through the summer without doing any serious work on the car, except to re-line the front brakes, a simple operation that involves taking out the engine unit, a fact I could not believe until I had it checked for me by the makers! To give some idea of the car’s capabilities, the door-to-door journey from just south of Edinburgh, where I am working, to my home near Newcastle, is 104 miles, and, on the two occasions I have gone home it has taken me 2 hours 17 mins. and 2 hours 18 mins., the actual 100 miles from the start being covered in 2 hours 10 mins. and 2 hours 7 mins., respectively: Not too bad for a 17-year old? The brakes are good, but heavy, and the steering is a delight, once one is used to it, but it scared the daylight out of me at first. It is very much an understeer car, and the first sharp corner I took at anything like speed, I needed every inch of road, and a good few feet of the opposite verge, to get round. The turning circle is very poor, and one sometimes feels a couple of locks will be required to get round the sharper bends of the Loch Lomond road!
I ran her in the Edinburgh Jubilee Cavalcade last October, with my mother as passenger. (One word of praise for the latter is deserved, as she is a great enthusiast, and drooled over all the old cars with me from 10.15 a.m. until 7 p.m., when the last Veteran left the King’s Park. She is aged just over 60, and is still driving her Hillman Minx, having started in 1922 on a Jowett, and has never had an accident of any sort. I only hope I can say the same after nearly 23 years of motoring.) The next day, my cylinder-head gasket blew completely, so I decided on a major overhaul.
I stripped engine, clutch, gearbox and differential, and found everything O.K., except a badly-worn clutch (it had been slipping a bit) and broken piston rings, which accounted for an oil consumption of about 8 or 9 hundred miles per gallon. These were replaced, and, after checking the head and finding it quite true, a new gasket was procured, and the whole shoot rebuilt, the operation taking about a month of evening and week-end work. The engine fired right away, and within 30 seconds the head gasket blew again.
To describe my hopeless feelings would be impossible, as I had under a week in which to become mobile for business reasons. I stripped the head once more, and this time checked the block, and my worst fears were realised; it was warped, and, though I had checked the head, like a fool I never thought of a warped block. Call me a moron, if you will, but we all make mistakes. It was obviously impossible to strip the whole engine and have the block machined, because of the time factor, so I had to fake something. By careful measurement, I isolated four hollows, opposite each bore, and between the studs on the side of the engine away from the inlet and exhaust manifolds. I then built up the solid-copper gasket with solder at these points, measuring the required thickness as near as possible with callipers, and tapering off from the maximum of 5 thous. in each hollow to zero at the edges. I assembled once more and again the engine fired first go, but after about two minutes, number two cylinder blew, with a loud hiss.
Nothing for it but to strip again, with spanners in my hand and despair in my heart, and this tme I cleaned and polished the block, and, using a huge soldering bit and a blow lamp. I built up the cast-iron block itself with solder, no easy job, I might add. The rough I took down with a coarse rasp, the rest with a fine file, and the last with emery cloth, using a 6-in. steel straight-edge, and a 1 1/2 thou. feeler-gauge as my measure. I had to build up some of the hollows as many as three times, by reason of my taking off too much, and it took me about 7 1/2 hours of heart-breaking work to get things done to my satisfaction. Once more, the head, blower and what have-you were assembled and, as a jointing compound, I used Holt’s “Overhaul,” so as to leave as little as possible to chance.
Once more I took hold or the handle and, with prayers, gave her it swing. She fired, and kept on firing and I went to bed happy for the first time in six nights.
And that is the position to-day. She gives me great joy, and an honest 25, 45, 60 and 80 to 85 m.p.h. in the gears, with acceleration from 0 to 50 in 12 secs., 20 to 25 m.p.g. and uses no oil. The silencer still tends to fall off at times, and once its over-close proximity to the floor boards or the duck’s back set the body on fire, about 5 miles south of Jedburgh. But who cares? I love her!