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ISKY RACING CAMS
The name Ed Iskenderian is a legend among racers worldwide.
Ed's life history parallels the proverbial success story. While attending Polytechnic
High School in Los Angeles, Ed's pet project was building a Model T Ford roadster.
Experiencing repeated crankshaft failure, Ed began searching for an engine with
a stronger lower end. The actual compression ratio turned out to be a whopping
13:1, an extremely high ratio for the early days of hot rodding. After graduating,
Ed obtained mechanical experience working as an apprentice tool and die maker.
Drawing on his tool making
and mechanical experience, Ed converted it to a universal cam grinding
machine. This machine produced
camshafts with a noticeable improvement in performance over the conventional
racing Ford camshafts. Ed saw that racers could benefit from the advancement
of higher-technology in racing so he created the first Hard-Face Overlay camshafts
in the industry and became the first to employ computers in camshaft design.
With the computer, Ed created the most advanced cam-profiles of the late 1950s
and early 60s like the famous 5-Cycle and Polydyne Profile 505 Magnum's along
with the very first Hydraulic racing camshafts in the industry. As the new camshafts
were delivering greater lifts and durations for higher R.P.M., the resulting
higher lift rates required advanced valve spring designs.
Recognizing this, Ed then introduced to the racing industry the first
Vasco Jet 1000 Valve Springs after having pioneered the first valve spring assemblies
for racing a decade before.
New Cams and Components were not the only thing Ed brought
to the young Drag Racing programs. In addition to the numerous racing advancements,
Ed also turned his interest to helping the stock/street enthusiasts. To
help fine tune racers' engines he offered the first "Ultra Rev-Kits"
for small block Chevy V-8 roller cams and the first anti-cam walk kit for the
Chevy V-8s, along with the first offset cam keys and bushings for adjusting
cam timing. In 1963, Ed in collaboration with a few other industry pioneers,
created the "Speed Equipment Manufacturers Association", now known
as the "Specialty Equipment Market Association" or "SEMA".
With the advent of the new small cars and the consumers trend
towards economy, Ed turned his efforts to enlarging his line of economy camshafts
and components, creating a camshaft that would deliver economy without robbing
performance. This led to the newest and strongest line of street/performance
camshafts. The SuperCams for economy/performance and the MegaCams, the maximum
in street/performance hydraulic camshafts. In the last three years, Ron has
developed over 100 new cam profiles using a new computer design program which
he developed to cut the design time by more than 3/4. In collaboration with
his brother Richard, they have designed over a dozen new valve spring combinations
for oval track and drag racing (blown alcohol and top fuel classes).
Isky's present location in Gardena, California consists of
a four-building complex of over 75,000 squre feet on property a full city block
long. Isky employs over 100 specialists, including engineers and technical advisers
to assist the thousands of Isky dealers throughout the world and the hundreds
of thousands of Isky customers. To answer the many questions that come in daily
from enthusiasts of circle track, off road, drag racing, Bonneville, truck and
tractor pullers, monster trucks, street, and stock cars and boats, Ed has written
many helpful pamphlets for technical advice on cam installations including installing,
valve timing, cam degreeing, dyno tuning, preventing roller cam walk and top
tuning tips.
As the world's largest racing, performance, and economy cam
manufacturer, Isky maintains a dynamometer testing program for constant improvement
of camshaft and valve train design. These tests are conducted daily in Isky's
new enlarged dyno facility. To properly evaluate and prove the efficiency of
Isky racing cams and valve train components, Isky maintains a continuous engine
testing program. Still another dynamometer is used exclusively for the purpose
of testing the endurance of racing valve gear components in today's OHV engines.
The final phase of testing is accomplished when the newly dyno tested cams and
components are coordinated with the best stock and performance equipment into
racing cars and boats as well as performance and stock street machines.
The results of these tests are available to all hot rodders, racers, and engine builders in the form of horsepower charts, plus information on carburetion, jetting, ignition, timing, and exhausts. At Isky Racing Cams you can always count on helpful, courteous service, the highest quality materials in all our products, the newest advancements and the finest workmanship available.
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Toyota:
6 Cyl. “Land Cruiser
PART#
|
DESCRIPTION |
TOYLNCRSRZ-50E4/06 |
Cams not available outright – Type (Combination) Intake (17
49) Exhaust (49 17) Lift (.425) Valve Lash hot (.018) Duration (246) |
TOYLNCRSRZ-99+E4 |
Cams not available outright – Type (Combination) Intake (21
57) Exhaust (57 21) Lift (.425) Valve Lash hot (.018/.020) Duration (258 |
TOYLNCRSRZ-99-005 |
Cams not available outright – Type (Combination) Intake (25
55) Exhaust (55 25) Lift (.406) Valve Lash hot (.016/.018) Duration (260) |
PART#
|
DESCRIPTION |
690144 |
Grind (440) Type
(Mild grind for Turbocharger) Lift
(.440) Valve Lash Cold (.008) Duration (280) .050 Duration (240) |
690146 |
Grind (465) Type
(Best all-around) Lift (.465)
Valve Lash Cold (.010) Duration (300) .050
Duration (240) |
690155 |
Grind (505B) Type
(Maximum competition) Lift
(.505) Valve Lash Cold (.0108) Duration (310) .050
Duration (255) |
PART#
|
DESCRIPTION |
TOY1200CorollaTC-66 |
Cams not available outright – Type (Combination) Intake (22
62) Exhaust (62 22) Lift (.420) Valve Lash hot (.018) Duration (264) |
TOY1200CorollaTC-84 |
Cams not available outright – Type (Competition) Intake (33
73) Exhaust (73 33) Lift (.420) Valve Lash hot (.018) Duration (286) |
TOY1200Corolla505A |
Cams not available outright – Type (Max. Competition) Intake
(40 80) Exhaust (80 40) Lift (.480) Valve Lash hot (.028) Duration (300) |
PART#
|
DESCRIPTION |
TOY1900CoronaTC4-66 |
Cams not available outright – Type (Combination) Intake (22
62) Exhaust (62 22) Lift (.420) Valve Lash hot (.018) Duration (264) |
TOY1900CoronaTC4-84 |
Cams not available outright – Type (Competition) Intake (33
73) Exhaust (73 33) Lift (.420) Valve Lash hot (.018) Duration (286) |
TOY1900Corona505A |
Cams not available outright – Type (Max. Competition) Intake
(40 80) Exhaust (80 40) Lift (.480) Valve Lash hot (.028) Duration (300) |
PART#
|
DESCRIPTION |
675128 |
Grind (228) Type
(Combination) Intake (32
68) Exhaust (68 32) Lift (.450) Lash Cold (.010) Duration (280) |
675174 |
Grind (74-S) Type
(Combination) Intake (42
78) Exhaust (78 42) Lift (.500) Lash Cold (.008) Duration (300 |
675183 |
Grind (Z-383) Type
(Combination) Intake ( )
Exhaust ( ) Lift (.450) Lash Cold (.006/.008) Duration (270) |
PART#
|
DESCRIPTION |
678135 |
Grind (Z-35) Type
(Combination) Intake (34
74) Exhaust (74 34) Lift (.508) Valve Lash Hot (.018) Duration (288)
.050 Duration (254) |
678150 |
Grind (L.L.505-T) Type
(Competition) Intake (34
76) Exhaust (76 34) Lift (.490) Valve Lash Hot (.028) Duration (290)
.050 Duration (242) |
678155 |
Grind (TH-55) Type
(Combination) Intake (19
61) Exhaust (61 19) Lift (.430 .430) Valve Lash Hot (.024) Duration (260)
.050 Duration (222) |
678160 |
Grind (Z-60) Type (Max. Competition)
Intake (36 76) Exhaust (76 36) Lift (.529) Valve Lash Hot (.018)
Duration (292) .050 Duration
(259) |
678177 |
Grind (TH-77) Type
(Competition) Intake (29
71) Exhaust (71 29) Lift (.460) Valve Lash Hot (.018) Duration (280)
.050 Duration (240) |
678190 |
Grind (TH-99+10) Type
(Competition) Intake (44
86) Exhaust (86 44) Lift (.480) Valve Lash Hot (.018) Duration (310)
.050 Duration (264) |
678199 |
Grind (TH-99) Type
(Competition) Intake (39
81) Exhaust (81 39) Lift (.480) Valve Lash Hot (.028) Duration (300)
.050 Duration (254) |
In order to hold costs down in oval track racing today we have
numerous "RULE" classes. Cam "Lift" rules, engine "Vacuum"
rules, "Carburation" rules and of course "Compression" rules.
I for one, certainly have no quarrel with compression Ratio rules, because if
you are talking true compression ratio, and it's properly measured and enforced,
it is absolute.
On the other hand, if it's a "compression effect"
rule or the measurement of cranking compression in the cylinder as read on a
compression gauge, then you have just pushed one of my buttons! However, before
I begin my tirade, let us review why we have such rules as these in the first
place. Do they exist so that we can go faster or slower; to make racing more
or less competitive? And, are those who break such rules punished or rewarded?
Well you say, the obvious answers to these questions are "slower",
"more competitive" & "punished". Wrong! Not when it
comes to compression "effect" rules!
Very simply, with a carburetor rule, he who installs a "bigger"
one usually goes faster, can be detected and penalized.
Likewise with a "cam lift" or "engine" vacuum rule.
You cheat by installing a bigger cam and although you go faster, we can catch
you and "you're outta there". Even with a compression ratio rule,
you can have your "15 minutes of fame" if you like, but eventually
you're going down because we can detect your indiscretion.
However, guess
what happens to those who comply with a "compression effect" rule?
Why, they are virtually always running a larger camshaft, go faster and of course
can never be punished because they are within the rules!
Impossible you say? Quite possible I contend and in fact this
is actually what happens virtually 100% of the time!
know, I'm in the camshaft business! Simply put, I believe compression
effect rules are the single most ridiculous rules in existence. Rules that guarantee
to keep speeds up, not down and actually penalize those with weaker engines
and fewer resources. How can that be? Please read on…..
With a given static compression ratio, you will always have
a higher reading on your compression tester gauge with a stock or low duration
cam, because you will be closing the intake valve earlier on the compression
stroke. The resultant longer effective compression stroke always delivers a
higher gauge reading. Now switch to a longer duration cam. Your intake valve
will close later, lowering your gauge reading because of the shorter effective
compression stroke. Some people feel this is impossible, insisting that if it
were true, why will you go faster with the bigger cam? The answer is,
the bigger cam will have higher compression effect in the cylinder
at higher engine speeds (where all that extra valve timing can do you some good),
however at lower speeds and especially at starter-cranking speeds, the effect
will be lower.
If you wish to prove this to yourself, simply recall how in
the past you may have noticed losing bottom end torque when installing a longer
duration cam. Do you think you lost that torque because of higher cylinder pressure?
Of course not, but that is only the logic of deductive reasoning. Lord only
knows what the "compression effect" rules people were thinking of
when they came up with this stuff. It doesn't make sense and just about any
cam grinder I know of, could have told them as much.
On the other hand, there are some cam grinders who are confused about
"compression effect" and cylinder flow dynamics. (Perhaps they consulted
one of them.)
What
Cause's Intake Reversion?: Once and for all, let us have the truth.
With the proliferation of the Motorsports Industry over the
years, many new faces have come on the scene.
In the cam grinding business today, there are many younger, less experienced
companies struggling for recognition of their talents and a few have turned
to postulating new theories in order to attract attention. However, they are
I believe unfortunately, too often guilty of shooting from the hip.
Two in particular are responsible for perpetuating the "myth"
that an earlier opening of the intake valve (even by a mere 2 or 3 degrees)
causes the phenomenon known as "reversion". Nothing could be further
from the truth! This misconception not only defies common sense, it also establishes
a false premise from which other, incorrect conclusions can be drawn. Simply
put, those who focus on overlap are on the wrong end of the cam-timing diagram!
Reversion, carburetor/Injector "stand-off" or the
general effect of the backing up of the intake Fuel/Air charge normally associated
with longer duration high-performance camshafts is actually caused by a Later
Intake Closing! How do we know
this to be true? The answer lies in the basic principles of physics. For as
with geometry and trigonometry, these sacred truths do not change simply because
someone chooses to ignore them in an attempt to garner a reputation.
Specifically, when the intake valve opens some 40 or more degrees
before T.D.C. at the end of the exhaust stroke, very little (virtually no) exhaust
gases remain in the cylinder. The piston is in the vicinity of T.D.C. (only
.425" down the hole @40° BTDC - on a typical 350" Chevy with 5.700" rods)
and no appreciable threat is posed to the forthcoming intake charge.
The "False Reversion Hypothesis" taken to an extreme would
lead one to the equally false conclusion that any overlapping of the intake
and exhaust valves is totally undesirable. Automotive engineers of the late
1800's and early 1900's used to think this way.
They were deathly afraid of overlap, so much so they actually employed
"Negative" overlap (minus 5 or 10 degrees) to be absolutely sure none
would occur. What was the result? These
engines were severely "throttled back" or limited to low speeds and
mediocre output. [ Reference: Iskenderian's Tech Article "Cam Degreeing
is Simple"] But, more progressive engineers of the early 1920's who performed
"brazen experiments" with longer duration cams proved these overlap
fears to be only so much "stuff and nonsense", as both power, rpm
and performance were actually improved. These engineers demonstrated that overlap
did not cause engines to quiver, backfire or lock-up on the spot! Although,
the ignorance displayed by their predecessors is easily explained by their lack
of experience, (internal combustion engine design being in it's infancy) it
was none the less the result of an incorrect hypothesis.
Should you need further persuasion that reversion is not caused
by earlier intake opening and the resulting extension of valve overlap, consider
this: What happens when you advance any camshaft? The intake as well as the
exhaust valves open earlier. Does this advancing of the cam cause more reversion?
Of course not. Throttle response and torque are enhanced. Yet, if these theories
were correct wouldn't the engine run more poorly, especially at lower RPM? The
answer is obviously yes, and because so, these theories are invalid. A brief
look at what's happening on the other end of the valve-timing diagram will tell
you why.
For when a camshaft is advanced, not only do both valves open
earlier but they of course also close earlier - and here in lies the key to
reducing Intake Reversion. Close your intake valves earlier and any tendency
for the occurrence of Reversion or the backing up of the intake charge as the
piston rises on the compression stroke will be reduced. It's not complex, nor
is it a mystery. And the circumstances surrounding it's occurrence have not
changed. In fact any experienced mechanic could tell you as much, for, as Ed's
good friend the legendary Smokey Yunick might say, "Only country smarts
are required to solve the problem."
In
a Normally Aspirated (unblown Engine)
Most stock camshafts from American production V8, V6 and 4
cylinder engines manufactured today are ground with the longer exhaust lobe
duration. Or, another way of looking at this is that they are ground with shorter
intake durations! The former embraces the viewpoint that either the Exhaust
Ports or Exhaust Pipe system is somewhat restrictive, and is in need of an assist.
The latter suggests that the intake system is rather efficient and cam timing
can be trimmed back a bit with out much sacrifice in power, in order to maximize
throttle response and cruising efficiency.
Take your pick here. There is no absolutely correct viewpoint
- because both are probably true! In
a stock engine running at conservative RPM levels, for the sake of overall efficiency,
fuel economy and a quiet smooth running engine, this staggering of intake and
exhaust duration is quite common and appropriate.
However, High Performance is another thing entirely. Change
one factor, let's say in this case, the exhaust system (installing headers and
larger pipes) and you have just negated in most cases, the need for that longer
exhaust lobe.
Now couple this change with a different intake system and camshaft
and you have really scrambled the equation. But, wait just a moment. Why is
it that so many people (racers & cam grinders alike) insist on running a
cam with longer exhaust duration regardless of what equipment is employed? The
answer is "habit". Most of them have been somewhat successful in doing
it their way and will probably never change unless virtually forced by circumstances
to do so.
Before we go any further however let's review what it actually
is we are trying to do with an engine when we attempt to make more power. Our
best result comes when we are cognizant of the fact that an engine is basically
an air pump. We pump it in and
out (although in a different form) and we have problems when one side or the
other is restricted. Balance or
the equilibrium or flow should be our objective, unless of course we are not
trying to make more horsepower!
Example #1 (Oval track racing) Here, I have often observed
that the most experienced drivers are those who are most likely to run a single
pattern (equal on intake and exhaust duration) cam. Why? Because such cams always,
I repeat always make more torque! These veterans have a more educated foot and
greater experience in feathering the throttle in the corners. They can therefore,
utilize the benefit of added torque, in the lower to mid RPM range, to their
advantage.
Their counterparts, the younger drivers on the circuit, generally
are not as experienced and may at times actually get “crossed up" in the
corners especially with a lighter car or when they are learning the ropes. In
their case, a longer exhaust duration is often the more appropriate choice.
It will often help them to drive better, more "flat footed" if you
will, without consequence. But please for the sake of accuracy, let us be truthful.
The benefit comes from an actual bleeding off of low to mid range torque, which
is always what happens when Exh. Duration is lengthened, not from any improvement.
The improvement, (if any) would come because of an improvement in scavenging
at the extreme upper end of the power curve and would usually be marginal at
best. Yet the so-called "extra power"
potential of a longer Exh. Duration
cam is most often why they are touted - power most people are backing away from
at the end of the strait away!
Example #2 (Drag Racing) At the drag strip it's a little different
and I feel more honest. Here, racers have long enjoyed longer exhaust and longer
durations across the board (If I may add specifically for the purpose of "killing"
low-endtorque) to keep the tires from too easily breaking lose. This has been
successful and sometimes actually results in a slight increase in top end power
- something you can actually use in drag racing since it is a full throttle
endeavor through the lights. Keep in mind here though, it's quite possible that
a longer duration cam overall would have done just as well or better. In other
words if you needed that longer exhaust for top end, perhaps the intake could
have benefited from such a lengthening as well.
One of my favorite expressions is how "The Drag Racing
mentality has infiltrated the ranks of Oval Track". Many have crossed over
and made the switch in the past 10-15 years and some have brought their preconceived
notions about how to cam an engine with them. A few may actually read these
concepts and if they do so will at least come away with a better understanding
of what they are doing. On the other hand they also could find that this information
might actually help their cars to run just a bit faster!
It is certainly an over simplification to make the statement
"that which is not wasted, should be inducted". However, in the case
of restricted intake systems and in particular 2-BBL carb rules, it is not far
off the mark. Engines with such restrictions are "choked off" to the
point where they will not run much past 6500 RPM (if even that high) without
dropping off sharply in power. You might have trouble running very fast yourself
if someone had your windpipe choked down to say 50 or 60% of it's normal capacity.
Under such conditions, would you volunteer to give blood at the Red Cross? Of
course not, but without knowing so, racers often do the equivalent with their
engines by running a camshaft better suited for a 4-BBL class! How So? ….
If you'll recall in last months tech tip: "Longer Exhaust
Duration: Is This Really Necessary?" I discussed how, through habit, many
racers and cam grinders alike are predisposed to running camshafts with longer
exhaust durations, whether they need to or not! Well, in the case of restricted
intake applications, if there was ever a situation in which you'd want to avoid
the longer exhaust "trap" it's here! Especially the 8, 10, 12 or even
longer degree spreads, I often discover people employing.
Use such a cam at you own risk - and don't be surprised to
find that your exhaust temperatures are unusually high.
Your headers in fact may even glow cherry red. There is a very good reason
for this. Raw (unburned) fuel is burning "late" or in the pipe (header/manifold).
You may have a good equilibrium of flow going here but there is just one problem.
Much of what should be inducted into the cylinder is being scavenged out the
exhaust! You see, although back pressure in an exhaust system can be restrictive,
the only thing that could be even worse is a reduction of it to the point where
you are now, in effect pulling a vacuum. In the case of an intake restriction,
very slight back pressure is preferable to avoid "over scavenging".
Yes, Yes I know. You are probably thinking "what's wrong
with a little scavenging?". Well, nothing if you can afford it. But with
intake restrictions (either small 2-BBL carbs and/or restrictor plates) you
must be very careful. You already have reduced intake potential and therefore
simply cannot be cavalier about valve overlap and scavenging or you'll be way
down on power and have those nice bright cherry red pipes to show for it! Case
in Point: One racer who called me was in this exact situation and was running,
not surprisingly, a 14 Degree longer exhaust duration. It was Friday afternoon
and he needed a cam the next day for the last "points race" of the
season and UPS had already picked up at Isky. "Too Bad" I said, "You
don't have a set of those low ratio break-in rocker arms because they could
really help in this case". " I do have some" he said "but
they are only 1.2:1 ratio - is that okay?" I told him to use them (on his
exhaust valves only of course) and he finished the race 2nd having come from
the back of the pack. Later we made him the right cam so he could avoid this
make shift approach.
Unfortunately, the symptoms are not always as obvious as in
this case to allow for a speedy diagnosis. Also, it's not only longer exhaust
duration that causes the problem. Although it is usually the primary offender,
it is often coupled with too close a lobe separation angle of say 104 Degrees.
A widening to 106 Degrees or preferably 108 Degrees (some go even wider) is
usually prudent.
I am not absolutely dead set against a slightly longer exhaust
duration in these cases as a 2-4 Degree longer exhaust lobe is permissible under
some circumstances (if your running a completely stock exhaust system including
mufflers for example). Each case is different, depending upon the equipment
employed. I might even recommend shorter exhaust duration to some; if I feel
they have "overdone" their exhaust ports and or exhaust system a bit.
What matters is the end result and if you're out of balance on one side simply
employ what I call the "Great Law of Compensation" to bring you back
to that equilibrium of flow.
So, how can you tell if you may need to make some of these
changes in your camshaft? Well, short of trying a lower exhaust rocker arm ratio,
you can increase exhaust valve lash .004" - .008" temporarily to see
if there is any improvement. You can also try and increase restriction (smaller
headers or pipes, or in the case of open headers a longer collector) and simply
observe the results. Remember, "One test is worth a thousand expert opinions".
Keep this old axiom in your "tool box" and you'll be ahead of the
game. How do you think Smokey's shop got to be "The best Damn Garage in
Town" anyway? Yes, he had those country smarts, but his experiences in
racing and his willingness to test are legendary!