The Guy Eight-Cylinder Car

An article from 'The Australian Motorist', 1st January, 1921. Courtesy of Brendan Kinsella.

Notable British Production Apparently only one British car is built with an eight-cylinder engine. This is the Guy, made by Messrs. Gut Motors Limited, of Wolverhampton. It formed a notable centre of interest at the last Olympia Show, but the production was considerably delayed. Now cars are leaving the works at a very satisfactory rate, and the makers’ initiative in placing an eight-cylinder on the market is being fully justified. The interest of this chassis is not by any means limited to its possession of an eight-cylinder engine, for the Guy embodies other details that are well worth the serious attention of owners and designers. It is the only chassis in the world in which the lubrication is entirely automatic to all those working components that require lubrication. Lubrication The lubrication of the engine is under pressure, and from the same system leads are taken to such chassis components as the steering gearbox, springs, shackle bolts, and clutch bearings. The method of operation is that on the horizontal shaft of the steering gear is cut a cam which, when the steering wheel is brought over to the extreme on the right lock, it bears against a plunger valve, and so opens a connection between the pipe leading from the engine oil pump to the pressure gauge on the dash board and to other pipes connected to the various chassis details. In every component to which this lubrication is applied there is embodied a cylinder having a tiny orifice, the area of which is strictly proportional to the amount of lubricant that the bearing surface it serves requires. After passing through this restricting orifice the oil is conducted by a wick to the actual hearing. Thus excess of oil is prevented, and the system does not work by merely forcing on to the bearing a flushing of oil on occasion – i.e. when the steering wheel is brought right over to the right, but the feed is continuous on account of the storing function of the wick. In practice the various parts so lubricated demonstrated to the eye that their lubrication is adequate. The Engine Accessibility has been studied in the engine design, as indeed in that of the chassis as a whole, to an extent that is quite unique. The two cylinder blocks arc set at an angle of 90 degrees, and the head of each pair of cylinders is detachable, being inclined at an angle of 45 degrees to the vertical. Thus decarbonisation necessitates the previous removal of quite a small component, and the area of the compression joint that has to be remade is considerably less than is the case with the ordinary four-cylinder engine, and the difficulty of securing a compression tight joint depends almost in strict proportion on the area of the joint. Above all, the cylinder head has its water cooling entirely separate from that of the cylinder barrel, the connection between the two separate water spaces being by means of external piping. Thus, when the cylinder head is removed a water joint is not broken in the ordinary sense, there being two pipes from the cylinder head – one to the main water uptake, and the other to the cylinder barrel, which are connected by a fastening similar to that usually employed between cylinder block and radiator. Besides this accessibility to the cylinder and piston heads the Guy has a characteristic and very attractive method of improving the ease of detachability of the piston and connecting rod complete. On either side of the crankcase opposite to each big end bearing there is an inspection port, which may be removed, and through which the bearing may be uncoupled, so enabling the withdrawal of the connecting rod and piston assembly complete. The crankshaft is of the two throw type, and careful designing has made possible the avoidance of forked big ends, as the bearing of each pair of connecting rods is mounted side by side on its crank pin. The arrangement of the valves is another characteristic feature, for these are disposed horizontally – i.e. their heads are vertical in the cylinders. The valve operation is by rocker arms from a camshaft containing only eight cams embodied in the crankcase at the base of the cylinder V. The aluminium cover which encloses the whole of the valve gear plays an important part in its lubrication. Situated as it is in the slip stream of the fan, and owing to its high heat conductivity, the aluminium cover has the effect of condensing the oil vapour that always fills the chamber. In its condensation this oil vapour falls onto the valve springs and stems, thus keeping them thoroughly lubricated, and also much reducing the risk of air leaks, which especially in connection with the inlet valves, is often an important and baffling cause of unsatisfactory engine behaviour. More About Lubrication Lubrication is, as has been stated, one of the most important of Guy features, The oil-filler is situated above the fan spindle bearing and incorporates a filter. As the oil is poured, a certain quantity is caught by a dash pot mounted immediately above the fan spindle, for which it ensures continual lubrication. The remainder of the oil passes over the chain connecting the crank shaft and camshaft, and thence through a large tray filter into the sump.

The Guy V8 engine and chassis.

Before it can reach the oil pump the oil has to pass through a third cage-type filter surrounding the pump entirely, and between pump and crank shaft there is situated a fourth and final filter, which is placed outside the crankcase, so that it is easily accessible for cleaning. Thus the Guy filtration arrangements for the oil are unusually elaborate, and they certainly should be more than merely effective to prevent the slightest suspicion of any foreign matter penetrating into the engine.

The crankshaft itself is hollow, and the oil is fed under pressure to its main bearings and big end bearings, separate leads also conducting oil under pressure to the five camshaft bearings. The pipe conducting the oil to the pressure gauge on the dashboard is inserted into a T-piece, through which the oil finds its way to the chassis when the valve is open in the manner previously described. The camshaft, which as stated, is chain driven, has mounted on it at its forward end a skew gear for driving a cross shaft, on the rear end of which is mounted the magneto, and on the off-side end the dynamo, the final drive to each of these units being taken through a flexible coupling. Cooling and Carburation Although thermosyphon cooling proved quite satisfactory under touring conditions at home, it was felt that as the Guy was to be a car for use the world over, pump cooling would be a genuine advantage to overseas users, therefore it was adopted. The fan is belt driven, and is assisted in its function by a cowling behind the radiator, an arrangement that has quite naturally been found to increase its efficiency considerably. Originally there were two carburettors, one for each cylinder block. In present models there is one carburettor mounted between the two cylinder blocks and having its induction pipe generously hot water jacketed. Engine, clutch, and gearbox, although not constructed as a single unit, are carried in a sub-frame three point suspended in the main frame, so that the advantages of unit construction are obtained without the corresponding disadvantages following from the inevitable employment of large, unwieldy aluminium castings. The sub-frame has its forward point of suspension in the centre of the forward cross-member of the main chassis frame, and its two rear points hang from a tubular cross-member just aft of the gearbox. In the event of an accident and the main frame getting damaged, this sub-frame, complete with its units, may be lowered to the ground and the main frame lifted over it, thus effecting a considerable saving of time in dismantling. The advantages accruing in the way of insulation from chassis distortion are, of course, obvious. The clutch is a fabric-lined cone, the springing of which has received special attention. It is abnormally light in operation, this being due both to careful design in the first instance and the leverage offered by the unusually long clutch pedal. The clutch-shaft between engine and gearbox contains two flexible joints, the first of the fabric type and the second of the sliding all-metal kind. The Transmission The gearbox itself gives four forward speeds and reverse. All its shafts are carried on ball bearings, which are provided with guards to prevent foreign matter from getting into the races, a detail of construction that incidentally makes possible the lubrication of the gear-box by thin oil instead of the commoner thick grease, Thin oil is undoubtedly preferable, provided it cannot escape, and precautions for this purpose on the Guy box are ample. Each gear wheel is a separate unit, so that should one become damaged its replacement can be made at a minimum of cost. The gear-operating lever, with its gate, is mounted directly onto the gearbox and takes no support from the chassis frame, although it is placed in the most popular British position - at the right hand of the driver. Immediately aft of the gearbox is a sliding all-metal flexible joint, which, like the one immediately forward of the box, is automatically lubricated by the gear oil. A third flexible joint of similar type is placed at the end of the propeller shaft (which is not enclosed in a torque tube) immediately in front of the differential housing, and should wear develop in any of these three sliding joints it may be taken up by removal, turning round and replacement of the rectangular steel bushes that are provided for the purpose. The full floating back axle has a spiral bevel drive, and the whole of its contents may be removed without previous dismantling of the road wheels. Lubrication of the axle is by oil, which is pumped to the whole of its working parts, road wheel bearings, and universal joint at the end of the propeller shaft. Both hand and foot brakes operate directly on the rear wheels through internal expanding shoes mounted side by side, and the compensation of the brake operation is carried to the actual shoes themselves beyond that in the brake operating rods. The shoes are expanded by a sliding cam instead of by the more ordinary fixed cam, a simple departure that in itself is enough to secure the full compensation of the brake shoes. The rear springs are underslung under the axle, and are of usual length, and neither front or rear springs are drilled, as is usually the case, but are attached to their axles by means of special clips registering with the spring pads on the axles, and avoiding weakening of the springs through their being drilled. The lubrication of the leaves of the rear springs is from the back axle. Of those of the front it is from the chassis lubrication system, and from the same source is obtained the lubrication of the rear shackle bolts, these being connected to the main pipeline by a short length of flexible tubing. A Petrol Tank, Showing Design Immediately above the filler for the tank there is a small horizontal lever, which in its normal position allows fuel to be drawn only from the main supply in the tank. When this supply becomes exhausted the lever is put into a position pointing directly aft, and then it brings into action the reserve supply of fuel. When in this position the tap, as it may be called, projects over the filler cap of the tank, which cannot be removed until the lever has been returned to its normal supply position. Thus one cannot refill one's tank without being aware that the supply was already very low, and one cannot accidentally leave the lever in the reserve supply position, so that one runs absolutely dry by accident. Steering is by worm and complete worm wheel, and the steering column is readily adjustable for rake, being steadied by a universal bracket from the dashboard. When necessary for export purposes, the steering column can be lowered right down to the chassis. The front axle is of ‘H’ section, its swivel pins having renewable bushes and the weight of their heads being taken by thrust bearings. Both swivel pins and road wheel bearings are lubricated by oil from a single reservoir on top of the axle swivels, and the detail lubrication of the chassis is conducted even to the front steering coupling rod.