CALIBRATED CRANKSHAFT HUB: A hub calibrated in degrees so that ignition and
cam timing may be accurately determined.
CAM COMPARATOR: This expensive equipment compares and evaluates production
cams to a precision master cam to check any possible variation.
CAM CONTOUR: See "CAM PROFILE."
CAM FOLLOWER: Usually a roller or flat faced companion to the camshaft that
transfers the action of the camshaft to the rest of the valve train by sliding or rolling
on the cam lobe surface.
CAM MASTER: After the design of the cam is computed, it's transferred to a precision
template or master. The master is then installed in the cam grinding machine to
generate the shape of the lobes of the production cam. The lobes on the master are
5 times that of a regular camshaft so that any variance from the actual computed profile
is reduced 5 times.
CAM PROFILE: The actual shape of the cam lobe. At Iskenderian, these profiles are
determined by an IBM computer.
CAMSHAFT: A shaft containing many cams that convert rotary motion to reciprocating
(lifting) motion. For every 2 revolutions of the crankshaft, the camshaft rotates 1
revolution. The lobes on the camshaft actuate the valve train in relation to the piston
movement in an internal combustion engine.
CARBURIZING: Gas carburizing is a method used by Iskenderian to heat treat steel
camshaft billets. In this method the camshaft is placed in a gas-carbon atmosphere
furnace and heated to the proper temperature. When the shaft has absorbed the
proper amount of carbon it's removed from the furnace and quenched to the proper
temper.
CAST BILLET: A term used by lskenderian to describe a camshaft which is made
from a casting. The material for the casting is a special grade of iron alloy called
Proferal."
CHILLED IRON LIFTER: A cam follower made from high quality iron alloy that is heat
treated by pouring the molten iron into a honeycomb mold with a chilled steel plate at
the bottom to heat treat the face of the lifter. It's compatible with steel and hardface
overlay cams only.
CLEARANCE RAMPS: The portion of the cam lobe adjacent to the base circle which
lifts at a constant slow speed (usually .00035-00055 in. per degree of cam rotation).
Its purpose, in theory, is to compensate for small deflections and take up the slack in
the valve train created by the valve lash.
COIL BIND: A valve spring that has been compressed to the point where the coils are
stacked solid and the spring's downward movement has stopped.
CONCENTRIC: Running true or having the same center. In camshaft terminology
the cam bearings and lobes are concentric to each other when the cam is straight
and there is .001 or less runout between all cams and bearings.
CORE DIAMETER: The diameter of the camshaft as measured between the cam
lobes.
CORRECTION GRINDING: The process by which another manufacturer's
camshaft is reground and corrected to the perfect geometric coordinates of an lskenderian
design.
COUNTER-BORING HOLE SAW: When installing high performance large diameter
valve springs, it's sometimes necessary to enlarge the spring bases on the
head by using this type of tool.
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D
DESMODROMIC: A special and complex type of valve train. Each valve is operated
by 2 lobes . . . 1 lobe opens the valve, the other lobe closes; therefore no
springs are used to return the valves to their seats.
DREAM WHEEL: A name for the Iskenderian Ratio Computer. Accurately converts
MPH to RPM, or RPM to MPH . . . Set gear ratio desired opposite tire diameter,
and read MPH opposite engine RPM. The dream wheel resembles a circular slide
rule.
DURATION: The amount of time measured in degrees that the valves are off their
seats during the lifting cycle of the cam lobe.
DYNAMOMETER: An apparatus for measuring the torque of an automobile engine
at various rpm. This torque reading is then converted to horsepower.
DYNO: An abbreviated word for dynamometer.
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ECCENTRIC: A disc having its axis of revolution out of its center of figure -- used
for reciprocating or lifting motion. The lobes of the camshaft are eccentric to the
cam bearings.
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F
FITTED DIMENSION: Referring to valve springs, this is the same as installed
height of the spring from its base on the cylinder head to its seat at spring retainer.
FLAME HARDENING: A heat treating process whereby a camshaft is exposed to
an open flame and then quenched (cooled in oil).
FLANKS: The sides of the cam lobe, or the portion of the lobe that lies between
the nose and the base circle on either side.
FORCED INDUCTION: See 'SUPERCHARGER."
FORGING: A metal object which was formed under pressure while in a red hot or
semi-molten state.
4130: A common grade of chrome-moly steel. The 41 represents the molecular
structure of chrome-moly steel, and 30 represents 301100 of 1% of carbon present
in the material. This carbon factor determines to what degree the material may be
heat treated.
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G
GEAR DRIVE: A special camshaft drive employing gears in lieu of the common
timing chain. The gear drive eliminates cam and distributor timing changes due to
wear or stretch of the stock timing chain. The gear drive gives immaculate (precision-
perfect) timing.
GILMER BELT: A trade name for a flat rubber cog belt used to drive superchargers.
The rubber belt has a core of steel wire for reinforcement and the inner side of
the belt has evenly spaced cogs which match grooves machined in the supercharger
drive pulleys.
GILMER PULLEY: A trade name which is used in conjunction with the Gilmer belt.
The pulley has grooves machined into it to mesh with the cogs on the Gilmer belt.
GROOV-MATIC "O" RING TOOL: A tool designed and manufactured by
Iskenderian to cut a groove around the cylinder. After the groove is cut, copper wire
is inserted so that .010 of the wire is above the plane of the block. The purpose of
the raised portion of wire is to increase the pressure on the head gasket around
the cylinder to prevent pressure leaks when supercharging the engine.
GROSS LIFT: The theoretical valve lift obtained by multiplying the cam lift by the
rocker arm ratio.
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H
HARDENABLE IRON LIFTERS: A cam follower made from high quality iron alloy.
Manufactured with the latest electronic furnace techniques, this
the cam bearings and lobes are concentric to each other when the cam is straight
and there is .001 or less runout between all cams and bearings.
HAROFACE OVERLAY: A process originated by Ed Iskenderian to apply a tungstencarbide,
chrome-nickel alloy to the outer surface of the cam lobe. These combined
alloys provide an extra-durable surface for the tremendous spring pressures and high
rpm of today's all-out competition engines. Camshafts that have been hardfaced are
for maximum competition only, and cannot be used on the street.
HEAVY DUTY SPLIT VALVE LOCKS: A component which resembles a semiconical
form on the outside. The inside of the cone is notched to coincide with the grooves
on the top of the valve. The valve locks prevent the valve from slipping through the
spring retainer. Iskenderian is the only company that manufactures special chromemoly
locks which replace the stock stamped steel part.
HEEL OF THE LOBE: Same as the "BASE CIRCLE" or the concentric portion of the
cam lobe.
HOLE SAW: See "COUNTER-BORING HOLE SAW."
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INERTIA RAM: A condition created by the piston as it reaches the bottom of its intake
stroke, by which the inertia of the intake air column continues to pack the cylinder until
the pressure exceeds that of the atmosphere.
INNER VALVE SPRING: For many racing applications a single valve spring may not
exert adequate pressure on the valve train and valve float may occur. Isky engineers
have determined the spring pressures necessary for each of our grinds and when this
pressure cannot be obtained with 1 spring, a smaller inner spring is used inside the
larger outer spring.
INTERFERENCE FIT: In a dual spring combination where the O.D. of the inner spring
and the 1.0. of the outer spring nearly approximate each other so that there is a slight
press fit between the 2 springs. This produces a dampening effect on valve spring
vibration and surge.
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L
LIFTER: See "CAM FOLLOWER."
LIFT GRAPH: By installing the camshaft in a bare block, the mechanic can plot the
lift of the cam in relation to each degree of camshaft rotation by installing a dial indicator
on the cam follower or tappet and a degree wheel on the crankshaft. All that is
necessary is to rotate the crankshaft every 5 degrees and take a reading on the dial
indicator at each of these intervals and transfer the readings to graph paper.
LOBE: The lobe is eccentric to the cam bearings of the camshaft and transmits a lifting
motion through the valve train to operate the valves. The design of the lobe determines
the usage of the camshaft - i.e., street use, all-out competition.
LOBE CENTERS: The distance measured in degrees between the center line of the
intake lobe and the center line of the exhaust lobe of the same cylinder.
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M
MICRO SPRING SHIMS: These shims serve the same function as the regular spring
shims except they are offered by Iskenderian in .005 increments. By combining different
thicknesses, the mechanic can precisely adjust spring height and pressure.
MUSHROOM LIFTER: Serves the same purpose as a regular lifter (flat tappet) but is
a different shape. The face of the lifter (the area that contacts the cam) is of a larger
diameter than that of the lifter body - . - it vaguely conforms to the shape of an inverted
mushroom.
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N
NET LIFT: The actual lift of the valve. This lift can be approximated by subtracting the
valve lash dimension from the gross lift figure in the catalog. Production tolerances
on rocker arms can vary this figure as much as ±.O1O.
NORMALLY ASPIRATED: An engine that utilizes either carburetors or fuel injection
without a mechanical device that forces the fuel/air mixture into the combustion
chambers (non-supercharged).
NOSE OF LOBE: The highest portion of the cam lobe off the base circle (full
lift position).
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OFFSET BUSHINGS: An eccentric bushing placed in the cam gear or sprocket to
advance or retard the camshaft with relation to the crankshaft. The dowel pin hole in
the cam gear or sprocket is drilled oversize to accept this bushing.
OFFSET KEY: A stepped key which is used to advance or retard the camshaft
where the cam contains a keyway rather than a dowel pin. Offset keys are also used
on the crankshaft to vary cam timing.
OHV: Abbreviation for over head valve."
OUTER VALVE SPRING: In a dual spring combination the outer valve spring is
always the larger of the 2 springs. It's usually made from a heavier wire than that of
the inner spring.
OVERLAP: A situation where both the intake and exhaust valves are open at the
same time when the piston is at (TDC).
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PARKERIZING: A thermo-chemical application whereby a non-metallic, oil absorptive
coating is applied to the outer surface of the camshaft. This permits rapid break in
without scuffing the cam lobes.
PISTON NOTCHING TOOL: Today's high lift camshafts often bring the engine's
valves too close to the piston crown. Therefore, it's necessary to cut deeper notches
in the piston crown to allow adequate valve-to-piston clearance, and prevent the
valves from striking the pistons. (Minimum recommended clearance is 100.)
POLY LOCKS: A valve train component which replaces the stock adjusting nuts on
Chevrolet, Pontiac and Ford rocker arms. These Poly-Locks allow for a finer and
more secure adjustment over a wider range and can be used with either mechanical
or hydraulic tappets.
PRE-LOAD: To load before applying a different load as with the Isky UltraRev Kit
which pre-loads the roller tappets to the cam lobe to keep them in constant contact.
PROFERAL IRON: A very high quality cast iron alloy. Used primarily for camshafts
because of its excellent wearing ability.
PUSHROD: A component of the valve train which connects the tappet and rocker
arm in an OHV engine. Iskenderian pushrods are manufactured from seamless
chrome-moly tubing and come either adjustable or non-adjustable. They are also of
special wall thickness for highest strength and lightest possible weight.
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RATIO COMPUTER: See "DREAM WHEEL."
REFINISHING: A process by which the cam face is refinished to the same geometrical
shape, however, being slightly smaller in size.
REGRINDING: Refers to an operation where a stock camshaft is modified to racing
specifications. This should only be done where it is difficult to obtain new cores, as
with imported cars.
REV LUBE: A non-detergent lubricant containing Molybdenum-Disulphide which is
spread on the cam lobes when installing a camshaft to prevent galling and insure
protection during the critical break-in-period - the first 5 minutes of operation.
ROLLER TAPPET: The roller tappet performs the same function as the mechanical
or hydraulic tappet. However, instead of sliding on the cam face, the lifter contains a
roller bearing which rolls over the cam surface. Its main advantage is that its operating
range is very flexible and can be used for street and strip, low or high speed
performance.
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SCREW-IN STUDS: Some engines are equipped with press-in studs from the factory
for locating and attaching the rocker arms. Under racing conditions, these studs
are prone to pulling out and must be replaced with screw-in type rocker arm studs.
Installation requires removal of the old studs and tapping the stud holes with a special
tap supplied with the installation kit.
SEAT BOUNCE: When there is a lack of valve spring tension, or where a poorly
designed cam having excessive deceleration and velocity characteristics is used,
the valve lands with such force on the valve seat that it has a tendency to bounce
on impact, causing a loss of compression and power in the cylinder.
SOLIDS: Purely mechanical cam followers. This follower or tappet requires either
adjustable pushrods or adjustable rocker arms to obtain the required valve lash.
SPLIT OVERLAP: An occurrence when both the intake valves and exhaust
valves are off their seats at the same time and the same distance. At this time, the
TDC mark on the harmonic damper should correspond with the pointer on the
engine.
SPRING FATIGUE: Valve springs have a tendency to lose tension after being run
in an engine for certain periods of time, because of the tremendous stress they are
under. At 6000 rpm, for example, each spring must cycle 50 times per second. The
tremendous heat generated by this stress eventually effects the heat-treating of the
spring wire and causes the spring to take a slight set (drop in pressure).
SPRING HARMONICS: See "SPRING SURGE."
SPRING HEIGHT: See "FITTED DIMENSION."
SPRING PRESSURE: The force exerted by a valve spring as it is compressed
(measured in pounds per sq. in.).
SPRING RETAINER: A stepped type washer made of either steel, titanium or aluminum
that transfers the force exerted by the compressed valve spring to the
valve.
SPRING SHIM: A thin metal washer which is placed between the spring seat and
the head. Its purpose is to compress the spring to the correct installed height and
tension.
SPRING SURGE: The factor which causes unpredictable valve spring behavior at
high reciprocating frequencies. It's caused by the inertia effect of the individual
coils of the valve spring. At certain critical engine speeds, the vibrations caused by
the cam movement excite the natural frequency characteristics of the valve spring
and this surge effect substantially reduces the available static spring load. In other
words, these inertia forces oppose the valve spring tension at critical speeds.
STACK SOLID: Refers to valve springs. See 'COIL BINDING."
STEEL BILLET: A solid piece of steel bar stock from which Iskenderian machines
most of their roller tappet camshafts.
SUPERCHARGER: A mechanical device which forces greater quantities of fuel
and air into the engine's cylinders by means of rotating impellers which are driven
from the power of the engine. The main types are centrifugal, Roots (GMC type)
and vane.
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ULTRA REV KIT: A device designed by Ed lskenderian .to preload the roller tappet
to the camshaft to allow higher rpm. The kit consists of 2 plates which are located
on each side of the valley chamber and a spring for each roller tappet. The springs
fit between the roller tappet and the valley plate.
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V
VALVE: A mushroomed shaped object which is used to regulate the incoming fresh
air! fuel mixture and the outgoing exhaust gases in the cylinder of an internal combustion
engine.
VALVE EVENT: The opening and closing points of the valve with relation to the
crankshaft.
VALVE FLOAT: A detrimental condition caused by over revving of the engine, or
by inadequate spring pressure, resulting in a lag of the valve gear components
where they fail to follow the dictates of the cam profile. Under this condition the
valve is a greater distance off its seat than it normally would be, causing a loss in
compression and power, as well as possible damage to the engine if the floating
valve strikes the oncoming piston.
VALVE GEAR: Same as "VALVE TRAIN."
VALVE LASH: Same as valve clearance. Valve lash is necessary to allow for thermal
expansion of the valve train components during operation.
VALVE SPRING DAMPER: A flat wound spring coil inside the outer valve spring,
which because of its rubbing contact on the inner surface of the coils, produces a
friction-dampening effect on valve spring surge (harmonics). Wherever possible,
lskenderian Valve Springs incorporate this damper coil.
VALVE TRAIN: The components or train of parts used to operate the valves in
conjunction with the camshaft.
VASCO JET 1000: The Chrome-Vanadium alloy steel used in the sky Vasco Jet
1000 racing valve springs which virtually eliminates the fatigue problem encountered
with ordinary valve springs.
VINCO CAMSHAFT INSPECTION OPTICAL DIVIDING HEAD: The world's most
accurate dividing head -- accurate to ±1 second of arc (1!3600 part of 1 degree)
and .000015 115 millionths of an inch). This machine is used to inspect all
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ISKY
ISKY
