minidat-technical.jpg (2637 bytes)

Jet to overhead valve engine

blank50.gif (825 bytes) Jet
A calibrated nozzle in a carburetor through which fuel is drawn and mixed with air. A carburetor normally contains several jets (idle, main, power) to provide the proper combustible mixture for all conditions of engine load and speed.

Jump Start
Cranking the engine of a car with a discharged or weak battery by attaching cables from the weak battery to a charger or helper battery.

A general term used to describe the sound made by loose or worn mechanical parts in an engine, such as a bearing.

Ladder Frame
A type of frame construction consisting of two heavy-section longitudinal members connected together stepladder fashion by smaller, transverse members. This type of frame is utilized on all 4x2 Hardbody's.

Laminated Windshield
A windshield consisting of a thin layer of rubbery plastic sandwiched between two sheets of glass. It is required for any car sold in the United States. Laminated windshields are safer than tempered glass windshields because damage, unless extensive, is localized and generally doesn't seriously impair vision. Also, when struck by a large blunt object, a laminated windshield fractures (or breaks) without puncturing, and the plastic inner layer holds the glass to reduce splintering.

Lead-Free or Unleaded Gasoline
Gasoline without tetraethyl lead or any other lead compound as an additive to increase octane rating or to reduce knock or detonation tendencies of the fuel. The elimination of such additives is one reason for the lowering of compression ratios. All new vehicles sold in the U.S. require lead-free gasoline.

Limited Slip Differential
A device in the differential that limits the speed difference between the two wheels. This prevents one wheel from spinning while the other is stationary, and so improves traction on slippery surfaces. (Also called Posi-Traction, GM trademark and Traction-Lok, Ford trademark.)

Live Axle
A rigid axle to which both rear wheels are mounted and through which the power is transmitted. Our Hardbodys and Van use a live rear axle. (Also see: Dead Axle/

Load Sensing Valve
A device that can sense the amount of weight in the bed of a truck and adjust the amount of braking force to the rear wheels to provide optimum stopping power under all load situations. This valve is found on all our Hardbodys and Pathfinder.

Lock-Up Torque Converter
A torque converter that contains a special clutch that forms a solid connection between the engine output shaft and the transmission input shaft when a certain, pre-set speed is attained. This reduces transmission friction losses and increases efficiency. (Also see: Torque Converter)

Any substance, but usually oil or grease, that is applied to moving parts to reduce friction. In an engine, lubricants not only reduce the friction, but also act as a seal to prevent leakage between parts, such as piston rings and the cylinder. The lubricant also acts to carry away much of the heat caused by friction and wash away the abrasive metal worn from friction surfaces.

Lubricating System
The oil pump, oil pan, oil coolers, tubing, filters and passages in the block and other parts that furnish oil to the moving parts and bearings of an engine.

Lug Nut
The nuts used to secure the wheels to the vehicle.

MacPherson Strut
A type of suspension that is known for being very efficient and compact. This suspension system employs a coil spring and shock strut, acting as an integral unit. Compared to conventional suspension systems, MacPherson struts use fewer parts, meaning a reduction in weight and elements that could wear out.

Main Bearing
Large insert type bearings that mount in an engine block and support the crankshaft.

Molded Seat
A type of seat that by its construction allows the manufacturer to avoid the use of seams in the seat covering.

A chamber attached to the exhaust pipe in which the exhaust gases expand and cool. It is usually fitted with baffles or porous plates that reduce, or muffle, the noise created by the exhaust.

Multi Link Rear Suspension
A system, generally employed only on driven wheels, in which a number of "links" are used to give vertical, lateral and fore-art support to the wheels. This system can be "tuned" or adjusted to give excellent steering characteristics during acceleration, braking and lateral G forces.

NAPS-X and NAPS-Z Engines
This is the designation for Nissan engines that feature optimum combustion for performance and economy with a low amount of exhaust emission. NAPS stands for Nissan Anti-Pollution System, which is protected by over 250 patents. These engines feature a "hemi" head combustion chamber and two spark plugs per cylinder. The NAPS-Z engine is used in four-cylinder Hardbodys and Van while the NAPS-X engine is used on the Stanza. (The term NAPS is no longer used in Nissan literature.)

Nissan Direct Ignition System (NDIS)
A system in which a separate ignition coil is supplied for each cylinder -- with one coil placed directly over each spark plug. In the Nissan system, each coil is controlled by a separate power transistor that is actuated by the E.C.C.S. electronic control unit. The Pulsar NX SE features this system.

Nissan Induction Control System (NICS)
A system used in multi-valve engines (such as the CAI8DE engine in the Pulsar NX SE model) in which there are two intake ports per cylinder. One port is open all the time. The second port opens, by way of a butterfly valve, only during high r.p.m. operation. This system provides driveability at low engine speeds and good power at high r.p.m. by maintaining high air velocity through the intake system. (Also see: Dual Plenum Intake System)

Oxides of nitrogen. NOx is produced when gasoline is burned in an engine. It constitutes one of the ingredients of photochemical smog. NOx emissions can be reduced by lowering peak combustion temperatures; two ways of accomplishing this are by lowering the compression ratio and by recirculating the exhaust gases.

An instrument for measuring and registering the miles and tenths of miles driven. Some cars also have an additional trip odometer, which can be reset to zero for conveniently measuring the miles driven during trips or between fuel fill-ups.

Oil Pump
An engine-driven pump that delivers oil to all the moving engine parts.

In the five-speed manual transmission, the fifth gear is built into the gearbox as a true overdrive. This means the driveshaft turns faster than the engine crankshaft. The overdrive feature saves fuel, and because the engine runs slower, engine wear and noise are reduced.

Overhead Cam (OHC)
An engine where the camshaft is located above the combustion chamber in the cylinder head, instead of in the cylinder block. Such a design allows the valves to respond more quickly to the needs of the engine. In addition, potential wear is reduced because there are fewer moving valvetrain parts. An engine that has one overhead camshaft operating all the valves is called a single overhead camshaft engine (SOHC). If the engine has one cam actuating the intake valves and another for the exhaust valves, it is known as a dual overhead camshaft engine (DOHC) or twin-cam engine.

Overhead Valve Engine (OHV)
An engine with both intake and exhaust valves placed directly over the piston. In this design, the camshaft is located in the block, and the valves are actuated by pushrods and rocker arms.