E for Efficiency

efficiencies is a word everyone uses let's take the case of Pat and Pete who are building houses both have the same materials that uses his materials efficiently Pete doesn't know that efficiency means getting the most out of what you put into any project or machine that builds a trim cottage but Pete ends up in the doghouse yes efficiency is important and it's most important in our automobiles we want to get as much fine automobile for our transportation dollar as possible and for our gasoline and oil dollar we expect mile after mile of carefree economical driving at the highest standard of performance in a motor car efficiency begins with the engine let's look at this simplified model to see what an efficient engine does to get the most power from every drop of gasoline first the fuel mixture is brought into the combustion chamber and cylinder it is important to get the right amount of fuel and air into the engine the engines second job is to compress the fuel mixture the piston moves up and as the mixture is compressed it becomes hot engineers no fuel burns better and makes more power at pressures and temperatures which are exactly right now for the third job a spark ignites the mixture as it burns the mixture expands enormously driving the piston to the bottom of the cylinder in a rush of power the fourth and last job the engine has to do is to push the burned gases out of the cylinder and into the exhaust manifold the engine is now ready to begin the cycle all over again the most efficient engine used in modern motorcars is the valve in head type this engine is found only in Chevrolet in its price class let's see why the valve in head engine gives more economy response and efficiency than any other type on the intake stroke Chevrolet's large intake valve opens directly over the combustion chamber and cylinder the fuel mixture is delivered over the piston in one sweeping motion there are no obstructions to cut down the smooth flow with some other engines such as this l-head type the job of getting the fuel mixture into the cylinder is more difficult the fuel mixture has to snake its way past the intake valve up into the combustion chamber and finally down into the cylinder the engine works harder to bring in the mixture because Chevrolet's intake stroke draws in a full charge of mixture with plenty of air for thorough burning this mixture is brought to the correct pressure and temperature with very little effort on the other hand some types of engines may draw in a skimpy charge of fuel and air in an effort to correct this fault higher compression ratios must be used that is the piston must squeeze the mixture harder without a gain in overall efficiency Chevrolet's piston travels only a short distance on each stroke the power is delivered smoothly and quickly in other engines the piston travels a long distance on each stroke this condition often goes hand-in-hand with excessive crankshaft bearing and piston wear on the exhaust stroke Chevrolet's big exhaust valve opens and the piston pushes the burned gases out of the cylinder and into the exhaust manifold smoothly and easily in other types of engines it is difficult or impossible to design passages for exhaust gasses without sharp corners and obstructions only the valve in head engine can do these for jobs with top efficiency better intake means better compression better compression means more power from each drop of gasoline and all these result in sparkling performance and valve in head economy there are many other reasons for valve in head superiority we know that the engine gets its power from the expansion of hot burning gases the more heat the greater the expansion and the greater the efficiency but in any engine some of the heat is lost through the walls of the combustion chamber the valve in head engine with its small combustion chamber as a small lost through the chamber laws in other types of engines the combustion chamber must be much larger this means larger heat losses this additional heat going out through the combustion chamber wall is heat that should have gone to work in the engine yes with the chevrolet valve and head engine you get more for what you put in more economy and more top-notch performance but that isn't all the overhead valve operating mechanism gives the valve in head engine other advantages for example to get the fuel and air mixture into the cylinder and the exhaust gases out valves should operate quickly and positively in Chevrolet this rocker arm gives the right leverage for the most efficient operation combines with long life and dependability here we have a slow rising cam working on the short end of a Chevrolet rocker arm which opens and closes the valve quickly and positively if a hydraulic valve lifters added as in the chevrolet 105 horsepower engine this action becomes even smoother and more possible in other types there is no memory so a fast-rising cam must be used the rod has so far to travel that it cannot follow the contour of the cams smooth yet higher engine speeds this may cause erratic valve action and shorter life both the chevrolet piston and chevrolet cylinder block are made of the same cast alloy iron a feature exclusive to chevrolet in the low-priced field and because parts made of the same material expand at the same rate when heated chevrolet pistons always fit right in the chevrolet valve in head engine valves and pistons are located in separate castings so that they can be completely surrounded by generous sized water jackets for controlled cooling of each part this is not possible where valves and piston both located in the cylinder block as in this l-head engine perfected lubrication is another Chevrolet extra the better the lubrication the more power available to drive the wheels and the longer the engine life chevrolet engineers knew that no one system could possibly do all the lubrication jobs with top efficiency to lubricate the cylinder walls oil mist is just right for the job the mist is caused by the high-speed action of a scoop on the connecting rod to lubricate the connecting rod bearings where pressures are high a pressure stream system is used at the engines main bearings there is a full pressure system to assure a constant and plentiful supply of oil to these all-important bearings to furnish exactly the right lubrication for the valve mechanism oil is delivered to the hollow rocker arm shaft under tell abraded pressure overhead valves slow rising cams cast iron fist' ins four-way oiling and superior cooling these are some of the reasons for the greater efficiency of the chevrolet valve in head engines valve and head engines have long been the choice of the world's fastest and most rugged racing cars airliners around the world rely on valve in head performance durability and dependability today there are more Chevrolet's on the road than any other automobile in the world chevrolet has built more valve in head engines than any other thank you as time goes on manufacturers of more expensive automobiles are turning to this engine design to give them the added durability performance and economy demanded of today's finest automobiles yet in its class only Chevrolet offers the brilliant performance outstanding economy and rugged durability of a valve in head engine with Chevrolet you drive the first and finest at lowest cost