Multiple carburetor barrels

While basic carburetors have only one venturi, many carburetors have more than one venturi, or "barrel". Two barrel and four barrel configurations are commonly used to accommodate the higher air flow rate with large engine displacement. Multi-barrel carburetors can have non-identical primary and secondary barrel(s) of different sizes and calibrated to deliver different air/fuel mixtures; they can be actuated by the linkage or by engine vacuum in "progressive" fashion, so that the secondary barrels do not begin to open until the primaries are almost completely open. This is a desirable characteristic which maximizes airflow through the primary barrel(s) at most engine speeds, thereby maximizing the pressure "signal" from the venturis, but reduces the restriction in airflow at high speeds by adding cross-sectional area for greater airflow. These advantages may not be important in high-performance applications where part throttle operation is irrelevant, and the primaries and secondaries may all open at once, for simplicity and reliability; also, V-configuration engines, with two cylinder banks fed by a single carburetor, may be configured with two identical barrels, each supplying one cylinder bank. In the widely seen V8 and 4-barrel carburetor combination, there are often two primary and two secondary barrels.

The spread-bore 4-barrel carburetor, first released by Rochester in the 1965 model year as the "Quadrajet" has a much greater spreadbetween the sizes of the primary and secondary throttle bores. The primaries in such a carburetor are quite small relative to conventional 4-barrel practice, while the secondaries are quite large. The small primaries aid low-speed fuel economy and drivability, while the large secondaries permit maximum performance when it is called for. To tailor airflow through the secondary venturis, each of the secondary throats has an air valve at the top. This is configured much like a choke plate, and is lightly spring-loaded into the closed position. The air valve opens progressively in response to engine speed and throttle opening, gradually allowing more air to flow through the secondary side of the carburetor. Typically, the air valve is linked to metering rods which are raised as the air valve opens, thereby adjusting secondary fuel flow.

Multiple carburetors can be mounted on a single engine, often with progressive linkages; two four-barrel carburetors (often referred to as "dual-quads") were frequently seen on high performance American V8s, and multiple two barrel carburetors are often now seen on very high performance engines. Large numbers of small carburetors have also been used (see photo), though this configuration can limit the maximum air flow through the engine due to the lack of a common plenum; with individual intake tracts, not all cylinders are drawing air at once as the engine's crankshaft rotates.

Tyre Maintenance Tips

How much do you care for your car tyres? In fact, when was the last time you thoroughly checked the wear and tear on the tyres? In our busy life, we tend to focus merely on the outer shell of the car ignoring other essential parts. Tyres in the car are like limbs of an athlete. You don’t realise but your sprinter might be crippled thanks to your ignorance.

1 Tyre change

What’s the right time to replace the old tyre with a new one? Experts believe a tyre should not be used more than 10 years also depending on factors like total kilometres driven, driving style and climate conditions et al. Rubber compounds used Auto Bild India reveals how to avoid mavericks from ripping you off and find a reliable repair station to work on your car Tyres that will never tire Here are some tips to keep your car tyres in good shape over a long period of time in tyres contain anti-oxidising chemicals that help to slow down the natural aging process of untreated rubber. However, tyres do deteriorate with age, which increases the risk of tyre failure, and there are many ways in which this can be spotted. Cracking on the side wall of the tyre, caused by its flexing, distortion of tyre tread or deformation of the carcass of the tyre.

The tyre being used currently should be replaced with a newtyre when the tread wear indicator (1.6mm height) is exposed.

2 Wheel bolt

If wheelbolts aren’t provided by the manufacturer make sure bolts used aren’t too short, there are chances of the wheel jumping out, or too long, they can damage the suspension.

3. Rotation policy

Rotate tyre positions if any irregular wear is found on any of the tyre or after every 5,000km. The first rotation is important as it sets the stage for long and even tyre wear. Make sure that all the tyres are exposed to the road equally. Rotating tyres from time to time would ensure that all the tyres are sharing the burden equally and no tyre is under or over exposed. Some manufacturers provide uni-directional tyres which can’t be used both sides, hence can’t be rotated like regular tyres.

4 Drive smoothly

Guess who curses you the most when you apply emergency brakes? Not the cop, but your car tyres. Rough braking takes away life of your car tyre and leads to early wear and tear. It’s important to drive at a constant pace and avoid applying frequent brakes. Driving rashly and breaking regularly leads to tyre skidding resulting in tyre losing its tread much quicker.

5 Aquaplaning

During monsoons tyres become more vulnerable to wear and tear. Rainwater that lingers in the ruts of roads places demands on driving. When the ruts are deep, the risk of hydroplaning is high, but anticipatory driving and good treads can reduce the risk. New tyres are the best weapons against hydroplaning. A tread pattern that channels water out from between the tyre and the road is the most effective means of preventing hydroplaning. Make sure the tyres are keeping water at bay.

6. Careful with jack

A hydraulic car jack should be used, which guarantees easy working and proper safety of the car and the person at the time of replacing tyre. Otherwise a standard jack provided by the car manufacturer should do. The base where the punctured tyre is being replaced should be should be flat and firm.

 

7. Air-pressure

Tyre pressures should always be checked and corrected (if necessary) when they are cold. It is vital that tyre pressures are maintained at the levels recommended by the manufacturer to ensure maximum tyre life, safety, the best ride and handling characteristics. Over or under-inflating tyres is likely to seriously impair their performance and may prejudice the safe use of the vehicle. Over-inflation increases overall tyre diameter, decreases the amount of tread in contact with the road, decreases sidewall flexibility and affects road-adhesion. Under-inflation decreases overall tyre diameter, increases sidewall flexion, generates higher tyre operating temperatures and difficult vehicle handling characteristics. Running an under-inflated tyre may cause premature tyre failure. Both over and under-inflation adversely affect tyre life.

 

8. Tyre storage

First clean the tyres and mark the position. Store in cool and dry place, away from petrol, oil, grease and chemicals. Lying or standing: it depends on the correct storage. When tyres are stored they should be stored in a cool, dry place away from sources of sunlight, heat and ozone such as hot pipes and electric motors. Tyres should be stored so there is no danger of water collecting inside them. Be sure that surfaces on which tyres are stored are clean and free from grease, gasoline or other substances which could deteriorate the rubber. Tyres exposed to these materials during storage or driving may be weakened and subject to sudden failure.

 

9 Mix and match

Most passenger tyres today are radial tyres. For best performance, we recommend the same size and type of tyre be used on all four wheel positions unless the vehicle manufacturer specified different sizes, front and rear, as original equipment. Check the vehicle placard. If only two radials are mounted with two non-radials, the radials should be mounted on the rear. If tyres of different types are mixed on a vehicle in any configuration, they should not be used for long periods and speeds should be kept to a minimum. Mixing or matching of tyres on four-wheel drive vehicles requires special precautions. Always check vehicle manufacturers’ manual for their recommendations

10 Wheel-alignment

A wheel alignment is part of standard automobile maintenance that consists of adjusting the angles of the wheels so that they are set to the car maker’s specification. The purpose of these adjustments is maximum tyre life and vehicle-travel that is straight and true when driving along a straight and level road, although most machines and the technicians who use them set the alignment to adjust for crowned roads, as well as correct tracking when driving on turns. Wheel alignment should be done after every 5,000km or whenever any irregular wear on tyre is found.

Top tips for economical driving

1. Ensure your car is well maintained. A poorly tuned engine could be using up to 50 per cent more fuel.

2. Travel at times when queues are shortest. Sitting in congestion uses up more fuel.

3. Eliminate short journeys if practical. Walk or cycle to the end of the road to pick up the paper.

4. Don’t carry unnecessary weight. Check you have got only the essentials in your boot and take off the roof rack if you don’t need it.

5. Look at the option of car sharing with friends and family, particularly on the school run.

6. The majority of cars run at their most efficient at 60mph. Every 5mph above that you drive, you will lose six per cent of your fuel economy.

7. Make sure you know where you are going before you set off. An estimated 350,000 tonnes of fuel is wasted every year by drivers who are lost.

8. Driving smoothly is much more efficient. Hard acceleration and sudden braking could use up to 40 per cent more fuel.

9. Consider changing your car to a smaller, greener model.

10. Is it absolutely necessary to take the car? The bus or train is much more efficient and can often be quicker, especially during rush hour traffic.

How Automotive Air Conditioning Works

You're stopped in traffic on an August afternoon. Sweat drips from your neck all the way down your back until your shirt absorbs it, making a damp spot between you and the seat. Your legs are either stuck to the vinyl upholstery or prickled by its cheap velvet. Your hands feel like they're about to slip off the steering wheel, and you're thankful your eyebrows are keeping the sweat from running into your eyes. Well, mostly.

What's missing from this picture? Automotive air conditioning. It's become nearly universal, with 99 percent of all new cars as of summer 2010 coming equipped with it. When it's missing, we notice.

It's also been with us longer than you might think. Packard invented automotive AC all the way back in 1939, and in 1940 was the first car company to offer factory-installed air conditioning. Of course, this early system didn't have a thermostat, but it was better than not having anything at all. The idea caught on, though, and by 1969, more than half of all new cars were sold with air conditioning built in. That's not including the aftermarket AC units that could be installed during the first heat wave of the year, when the new owner regretted his penny-pinching at the dealership in January.

Eventually, it was determined that the refrigerant used for decades in automotive AC, known as R-12, CFC-12, or its brand name Freon, was damaging the ozone layer (it's a chlorofluorocarbon). It was banned from being manufactured in the United States and an alternative, called R-134a or HFC-134a, was required for all cars manufactured after 1996. Now, any car older than that needs to be retrofitted with a new system that can use the newer, safer refirenge.

Air conditioning has worked pretty much the same way for its entire existence: it cools and removes humidity from the air. There are three main parts to the system -- the compressor, condenser, and evaporator -- that achieve this, plus a few other parts to keep the system running smoothly. Let's take a look at each.

double helical gears

Double helical gears, overcome the problem of axial thrust presented by "single" helical gears, by having two sets of teeth that are set in a V shape. A double helical gear can be thought of as two mirrored helical gears joined together. This arrangement cancels out the net axial thrust, since each half of the gear thrusts in the opposite direction resulting in a net axial force of zero. This arrangement can remove the need for thrust bearings. However, double helical gears are more difficult to manufacture due to their more complicated shape.

For both possible rotational directions, there exist two possible arrangements for the oppositely-oriented helical gears or gear faces. One arrangement is stable, and the other is unstable. In a stable orientation, the helical gear faces are oriented so that each axial force is directed toward the center of the gear. In an unstable orientation, both axial forces are directed away from the center of the gear. In both arrangements, the total (or net) axial force on each gear is zero when the gears are aligned correctly. If the gears become misaligned in the axial direction, the unstable arrangement will generate a net force that may lead to disassembly of the gear train, while the stable arrangement generates a net corrective force. If the direction of rotation is reversed, the direction of the axial thrusts is also reversed, so a stable configuration becomes unstable, and vice versa.

Stable double helical gears can be directly interchanged with spur gears without any need for different bearings.

Equation of motion

The Cardan joint suffers from one major problem: even when the input drive shaft axle rotates at a constant speed, the output drive shaft axle rotates at a variable speed, thus causing vibration and wear. The variation in the speed of the driven shaft depends on the configuration of the joint, which is specified by three variables:

•  The angle of rotation for axle 1
•  The angle of rotation for axle 2
•  The bend angle of the joint, or angle of the axles with respect to each other, with zero being parallel or straight through.

These variables are illustrated in the diagram on the right. Also shown are a set of fixed coordinate axes with unit vectors  and and the planes of rotation of each axle. These planes of rotation are perpendicular to the axes of rotation and do not move as the axles rotate. The two axles are joined by a gimbal which is not shown. However, axle 1 attaches to the gimbal at the red points on the red plane of rotation in the diagram, and axle 2 attaches at the blue points on the blue plane. Coordinate systems fixed with respect to the rotating axles are defined as having their x-axis unit vectors ( and ) pointing from the origin towards one of the connection points. As shown in the diagram,  is at angle  with respect to its beginning position along the x axis and  is at angle  with respect to its beginning position along the y axis.

 is confined to the "red plane" in the diagram and is related to  by:

 is confined to the "blue plane" in the diagram and is the result of the unit vector on the x axis  being rotated through euler angles ]:

A constraint on the  and  vectors is that since they are fixed in the gimbal, they must remain at right angles to each other:

Thus the equation of motion relating the two angular positions is given by:

with a formal solution for :

The solution for  is not unique since the arctangent function is multivalued, however it is required that the solution for  be continuous over the angles of interest. For example, the following explicit solution using the a tan (y,x) function will be valid for :

The angles  and  in a rotating joint will be functions of time. Differentiating the equation of motion with respect to time and using the equation of motion itself to eliminate a variable yields the relationship between the angular velocities  and :

As shown in the plots, the angular velocities are not linearly related, but rather are periodic with a period twice that of the rotating shafts. The angular velocity equation can again be differentiated to get the relation between the angular accelerations  and :

Fitting new piston ring

When fitting new piston rings or breaking them in within an engine, the end gap is a crucial measurement. In order that a ring may be fitted into the "grooves" of the piston, it is not continuous but is broken at one point on its circumference. The ring gap may be checked by putting the ring into the bore/liner (squared to bore) and measuring with a feeler gauge. End gap should be within recommended limits for size of bore and intended "load" of engine. Metals expand with a rise in temperature, so too small a gap may result in overlapping or bending when used under hot running conditions (racing, heavy loads, towing) and, even at normal temperatures, a small ring gap may lead to ring gap closure, ring breakage, bore damage and possible seizure of the piston. Too large a gap may give unacceptable compression and levels of blow by gases or oil consumption. When being measured in a used bore, it may indicate excessive bore wear or ring wear. (Radial wear on ring face reduces thickness of used/worn ring (face wear in bore) essentially decreasing face circumference of ring and thereby increasing size of ring end gap.)

It is considered good practice to build a new engine with the ring gaps staggered around the circumference of the bore. This means that any escaping gas must negotiate a labyrinth before escaping past the rings. However, while the engine is running, the rings will tend to rotate around the piston and not remain in the position as fitted. Many rings will then stick in one spot at random and remain there for the life of the engine. For this reason, ring position during build cannot be considered to be important although most engine builders would feel uncomfortable assembling an engine with the gaps aligned.

When fitting new rings to a used engine, special "ridge dodger" rings are sometimes used for the top compression ring, to improve compression and oil consumption without reboring the cylinder. These have a small step of iron removed from the top section to avoid making contact with any wear ridge at the top of the cylinder, which could break a conventional ring. These are not widely recommended, however, as they are usually not required and may give inferior oil consumption. A more acceptable method is to remove the wear ridge with a "ridge reamer" tool before lightly honing the bore to accept new rings. In fact, if the "ridge " is measured it will generally be apparent it is not really a ridge but a relatively local hollow caused by the top ring near the ring reversal point. The upper edge of this hollow will take the form of a "ramp" about 2mm long from the point of maximum wear to the point of zero wear. In this case, there is not actually any ridge to hit, so light honing may be all that is required.

During engine assembly, a piston- ring compressor is used to evenly squeeze the rings long enough to slide the piston into the cylinder.

Rings are not a very expensive part, but fitting new ones is usually very costly. This is because to fit them, the mechanic must essentially take the whole engine apart. Therefore the labour costs are the major factor. Once going that far, one might as well correct many other problems found inside - so fitting new rings is usually done as part of an entire engine rebuild/reconditioning

piston ring in automotive

Most automotive pistons have three rings: The top two while also controlling oil are primarily for compression sealing (compression rings); the lower ring is for controlling the supply of oil to the liner which lubricates the piston skirt and the compression rings (oil control rings). At least two piston rings are found on most piston and cylinder combination. Typical compression ring designs will have an essentially rectangular cross section or a key stone (right angled trapesodial) cross section. The periphery will then have either a barrel profile (top compression rings) or a taper napier form (second compression rings or scraper rings). There are some taper faced top rings and on some old engines simple plain faced rings were used.

Oil control rings typically are of three types:

1. single piece cast iron
2. helical spring backed cast iron or steel
3. multipiece steel

The spring backed oil rings and the cast iron oil rings have essentially the same range of peripheral forms which consist of two scraping lands of various detailed form. The multipiece oil control rings usually consist of two rails or segments (these are thin steel rings) with a spacer expander spring which keeps the two rails apart and provides the radial load.

The piston might be a fairly loose fit in the cylinder. If it were a tight fit, it would expand as it got hot and might stick tight in the cylinder. If a piston sticks (seizes) it could cause serious damage to the engine. On the other hand, if there is too much clearance between the piston and cylinder walls, much of the pressure from the burning gasoline vapour will leak past the piston (a condition known as blow by) and into the crankcase, and the push on the piston from combustion will be much less effective in delivering power.

CNG Fuel Types

CNG vehicles can use both renewable CNG and non-renewable CNG.

Conventional CNG is produced from the many underground natural gas reserves are in widespread production worldwide today. New technologies such as horizontal drilling and hydraulic fracturing to economically access unconventional gas resources, appear to have increased the supply of natural gas in a fundamental way.

Renewable natural gas or biogas is a methane‐based gas with similar properties to natural gas that can be used as transportation fuel. Present sources of biogas are mainly landfills, sewage, and animal/agri‐waste. Based on the process type, biogas can be divided into the following: Biogas produced by anaerobic digestion, Landfill gas collected from landfills, treated to remove trace contaminants, and Synthetic Natural Gas (SNG).

ABS with EBD and EBA

Anti-lock Braking System (ABS) with Electronic Brakeforce Distribution (EBD) and Emergency Brake Assist (EBA)
The standard Anti-lock Braking System (ABS) makes for safer stopping and cornering. Electronic Brakeforce Distribution (EBD) assists in balancing braking force between front and rear wheels, depending on driving and vehicle load conditions. Working alongside EBD is Emergency Brake Assist (EBA), a system that interprets a driver’s braking behaviour and automatically initiates full braking faster than a driver ever could.

Oldsmobile jetstar

(1964–1966) - Life for the somewhat obscure Jetstar I started in 1964. It was designed to be a low cost option to the successful full size Starfire series - more of a direct competitor to the pontice. Standard equipment included the 345 hp (257 kW) 394ci Starfire engine, vinyl bucket seats and console. Keeping the “sport” part of the Starfire, it possessed less of the luxury and glitz. It weighed in at 4028 pounds, and 16,084 were produced for 1964. It was a Starfire without the frills and was informally dubbed “the poor man’s Starfire”. Proving to be an ill-fated model, 1965 concluded the 2 year run for the Jetstar I. Only 6,552 were sold. The introduction of the Pontiac GTO and Oldsmobile 4-4-2 in 1964 insured the future of the musclecars were the intermediates, and the front-drive Toronado loomed big in Oldsmobile's future taking over the flagship status from the Starfire. Further confused with its lesser brethren with the Jetstar 88 nameplate, there was no way but out for the Jetstar I. And close examination of prices revealed that unless one bought a sparsely optioned JS1, there was little financial incentive to buy a JS1 over the Starfire. Take the $3602 base price and add the $107.50 power steering, the $43.00 power brakes, and the $242.10 automatic transmission (all standard on the Starfire), and you had a $4,000 Jetstar I. And less than $150 more would buy you the $4148 based priced Starfire, which not only included those standard features but a more luxurious leather interior. But lost in the mix was a jewel of a high-performance car in the ’65 Jetstar I. Trimmed down to 3963#, the ’65 model was an overlooked performance car. The new 370 hp (276 kW) 425ci Starfire engine delivered 470 lb·ft (637 N·m) of torque, was durable, and was quite an improvement over the ’64 394. How serious was that horsepower and torque in ’65? If you wanted this much power in a Pontiac, it was only available in the top-of-the-line 421 HO Tri-Power engine that was not standard in any Pontiac model, but an extra-cost option. The new Oldsmobile Turbo Hydra-Matic transmission was a vast performance improvement over the previous “slim-jim” Hydra-Matic transmission. But best of all, Oldsmobile offered the Muncie 4-speed with Hurst shifter in ’65. Oldsmobile boasted in a 1965 press release that “a Jetstar I proved to be the top accelerator of the entire event” at the 1965 Pure Oil Performance Trials in Daytona beach. Those trials were sanctioned and supervised by NASCAR.Note: between 1964 and 1966, Oldsmobile named its least expensive full size model the Oldsmobile Jetstar 88 which the Jetstar I was not related to, and priced $500–$600 below the Jetstar I.

olds........................

Early on in their history, Olds enjoyed a healthy public relations boost from the 1905 hit song "In My Merry Oldsmobile". The well known song was updated in the fifties to sing about "The Rocket 88".

The strong public relations efforts by GM in the 1950s was epitomized in the motorama, a "one company" auto show extravaganza. Millions of Americans attended, in a spirit not unlike a "mini-world's fair". Every GM division had a "Dream Car". Oldsmobile's dream/concept car was called "The Golden Rocket".

1970 Oldsmobile 442

The Dr. Oldsmobile theme was one of Oldsmobile's most successful marketing campaigns in the early '70s, it involved fictional characters created to promote the wildly popular 442 muscle car. 'Dr. Oldsmobile' was a tall lean professor type who wore a white lab coat. His assistants included 'Elephant Engine Ernie' who represented the big block 455 Rocket engine. 'Shifty Sidney' was a character who could be seen swiftly shifting his hand using a Hurst shifter. 'Wind Tunnel Waldo' had slicked back hair that appeared to be constantly wind blown. He represented Oldsmobile's wind tunnel testing, that produced some of the sleekest designs of the day. Another character included 'Hy Spy' who had his ear to the ground as he checked out the competition.

In the 1970s, the mid-size Oldsmobile Cutlass public relations campaign in the late 1980s that proclaimed this was "not your father's Oldsmobile." Ironically, many fans of the brand say that the declining sales were in fact caused by the "this is not your father's Oldsmobile" campaign", as the largest market for Oldsmobiles was the population whose parents had, in fact, owned Oldsmobiles and that by going away from the traditional vehicles that Oldsmobile's brand was built upon, lost many loyal buyers and put the brand on a collision course with pontiac and buick which led to internal cannibalization and a downfall from which it could never recover.

A 1902 advertisement for Oldsmobile - Galveston Daily News, December 28, 1902

A 1904 advertisement for Oldsmobile - Syracuse Post-Standard, September 30, 1904

A 1905 advertisement for Oldsmobile.

A 1906 Advertisement for Oldsmobile, Amos Pierce Automobile Company - Syracuse Post-Standard, February 10, 1906

Oldsmobile four-cylinder touring car (Model S) - Syracuse Herald, April 7, 1906