Performance camshaft

[zurinazwan]

HOW TO SELECT A PERFORMANCE CAMSHAFT
When selecting a performance camshaft, consider the use for which the vehicle will be required.
We all know the claims: 20 BHP extra. This sounds great – but think! These automotive manufacturers can’t be that silly to disregard
20 BHP by changing a camshaft.
Ask yourself! Where is this 20 BHP? Probably not where you will ever use it at 7500 rpm. Well, probably we will use it, occasionally;
it would be nice to have in reserve.
Hold on! In this world there is no such thing as a “free meal”. What’s the possible trade-off of this 20 BHP? It could be a loss of 10
BHP at 2500 rpm. This means, each time you accelerate through 2500 rpm, you could lose 10 BHP. This to me, doesn’t sound too
good.
SOLUTION
Be conservative! Don’t over-cam your engine. Choose your cam for the correct application. Consider! Fit a milder cam and increase
your power by 10 BHP at 3500 rpm.
Remember! You get this 10 HP every time you accelerate through 3500 rpm. Multiply this by 10 HP each time you drive through 3500
rpm then deduct the times you reach 7500 rpm.
I’m sure you will find more horsepower on the 3500 rpm side than the 7500 rpm calculation.

CAMSHAFT SELECTION
You will see that each camshaft has a Part No and Phase No. The Part Number designates the make and model/the duration period of
the inlet camshaft/the valve lift of the inlet camshaft and whether the camshaft profile is hydraulic. So if we look at the Ford 1300/1600
CVH RS Turbo XR3i XR2 Camshaft Data Sheet we see the following:-
FORC/206/420/H PH2
FORC Specifies the make and engine type
260 Specifies the duration
420 Specifies the lift on the inlet valve
H Specifies that the camshaft is designed for hydraulic cam followers
PH2 Specifies the type of use the camshaft is recommended for


SELECTING YOUR CAMSHAFT
All the camshafts in this brochure have a Phase Number after the Part Number. Phases 1 to 5 will help you to select the camshaft that
meets your requirements.
PHASE 1 (PH1) ROAD CAMSHAFT
This is a camshaft that would be used for road use and will normally run with standard carb or injection system and can be fitted without
additional tuning equipment. It is meant for town use and will have a smooth tick-over and will give its increase in power in the low midrange.
Other modifications to the engine will increase the performance of this cam.


PHASE 2 (PH2) FAST ROAD CAMSHAFT
This is a camshaft for increasing mid-range of the engines and is meant for mild competition use and where the driver requires an
increase of power in the mid-range without suffering too much loss of power in the low-range. The tick-over will be heavier than a standard
engine. The fuel system may have to be modified and the cam will work to its optimum with modifications to the cylinder head,
inlet/exhaust system and possibly the management system.
PHASE 3 (PH3) FAST ROAD RALLY
This type of camshaft is really the limit for normal road use. It will require fuel system and management modifications. It will have a
noticeable loss of low-down power and the tick-over will be heavy. For competition use, where mid-range power is important and road
use where the maximum power is required.
PHASE 4 (PH4) TARMAC RALLY SPRINT RACE CAMSHAFT
This camshaft is for competition use only and can be considered as a _ race cam. It could be used on the road, but would not be suitable
for use in traffic. It will have a very heavy tick-over and there will be a noticeable loss of power below 3500 rpm. Its main use is
for a torque race cam, giving a strong surge of power in the upper range power, yet still having the ability to floor the throttle below
5000 RPM and pull cleanly away. It will require modifications to the carb/injection system, cylinder head and induction exhaust system.
PHASE 5 (PH5) FULL RACE CAMSHAFT
For race use only. Not suitable for road or rally use,. Little power below 5000 RPM . Will have virtually no idle and will require
carb/injection, exhaust/induction., cylinder head and engine management modifications.






MATERIAL TYPE (PERFORMANCE CAMSHAFTS)
You will note that we have a material description at the end of the camshaft specification. This informs of the following:
Billet
This means that the camshaft has been turned from a round steel bar and will normally be nitrided after grinding.
We use this method for low volume production and, due to the work involved, they are always more expensive than cast blanks
Blank
Unless specified, the camshaft is made from a chilled iron casting. This is the best material for camshafts, as it has far superior wear
characteristics than any other material.
REPRO
A regrind on an existing camshaft, only suitable for mild grinds on existing chilled iron camshafts. If you regrind case hardened steel
camshafts you will remove the case hardening. We only regrind chilled iron cams, but prefer to supply new units


INFORMATION ON CAMSHAFT MATERIAL
Camshaft material, i.e., what the camshaft is made from, is the most important detail in stopping premature wear of performance
camshafts.
There are various materials that camshafts are manufactured from:-
CAST IRONS
1.HARDENABLE IRON
This is Grade 17 cast iron with an addition of 1% chrome to create 5 to 7% free carbide.
After casting, the material is flame/or induction hardened, to give a Rockwell hardness of 52 to 56 on the C Scale.
This material was developed in the 1930’s in America as a low-cost replacement for steel camshafts and is mainly suited in applications
where there is an excess of oil, i.e., camshafts that run in the engine block and that are splash-fed from the sump. (This is the material
that the Ford OHC camshafts were manufactured from).
It is not the most suitable material for performance camshafts in OHC engines.
As a company, we only use this material for performance camshafts if the camshaft is splash-fed in the sump.

2.SPHEROIDAL GRAPHITE CAST IRON KNOWN AS SG IRON
A material giving similar characteristics to hardenable. Its failing as a camshaft material is hardness in its cast form, i.e., Rockwell 5,
which tends to scuff bearings in adverse conditions. The material will heat treat to 52 to 58 RockwellC. This material was used by Fiat
in the 1980’s.

3.CHILLED CHROME CAST IRON
Chilled iron is Grade 17 cast iron with 1% chrome. When the camshaft is cast in the foundry, machined steel moulds the shape of the
cam lobe are incorporated in the mould. When the iron is poured, it hardens off very quickly (known as chilling), causing the cam lobe
material to form a matrix of carbide (this material will cut glass) on the cam lobe.
This material is exceedingly scuff-resistant and is the only material for producing quantity OHC performance camshafts.
CONCLUSION OF CAST CAMSHAFTS
When purchasing a camshaft, enquire which material the camshafts are produced from. A chilled iron camshaft may be more expensive,
but its resistance to wear in all conditions, far exceeds any other type of cast iron.
STEEL CAMSHAFTS
1.CARBON STEEL – EN8/EN9
Used mainly in the 1930 to 1945 period and is currently used for induction hardened camshafts in conjunction with roller cam followers,
due to the through-hardening characteristics of the material.
2.ALLOYED STEELS – EN351 AISI 8620 and EN34 etc
Used by British Leyland in the A Series and B Series engine and best when run against a chilled cam follower.
3.NITRIDING STEEL – EN40B
The best steel for camshafts. When nitrided it gives a surface hardness and finish similar to chilled iron.
We used this when replacing chilled iron camshafts in competition engines. This material is used on several of the current F1 engines.
CONCLUSION
In general, steel is a good camshaft material. However, the type of steel has to be matched with the cam follower it runs against, as
different grades of steel have different scuff characteristics.
GENERAL CONCLUSION OF CAMSHAFT MATERIAL
This has been a very simplified explanation of camshaft materials, based on over 38 year’s experience. It may assist you to ask the
correct questions when purchasing performance camshafts.

CAMSHAFT INSTALLATION
1. We recommend new cam followers be fitted, purchased from us or from a Main Dealer.
2. Check that on full lift on the inlet and exhaust valve spring there is 0.030”/0.75mm clearance between the centre coils of the
valve spring,. On hydraulic engines a dummy solid cam follower should be used for this purpose.
3. Rotate the engine by hand and ensure that the valves miss the pistons and block by 0.060/1.5mm
4. Don’t over-spring the camshaft. Most modern engines have valve springs that can be used for Phase 1 and 2 camshafts and in
some applications Phase 3 cams. So use the lightest spring possible.
5. Before starting the engine, remove spark plugs and spin the engine up until the oil pressure is indicated.
6. Ensure that the cam being fitted is identical to the unit being replaced, except for the cam profiles.
7. Set the camshafts up on the timings supplied on the data sheet. You can change the characteristics of the engine by moving
the opening and closing points. This will not have any great effect on the Phase 1 and 2 type of cams, but can make a
noticeable difference to the Phase _/and 5 camshafts, due to the effect on the air wave pulses in the induction and
exhaust systems.
The air wave pulses can be affected by induction length/diameter, exhaust length and silencer baffling, so the timing figures
we supply are based on experience, but to obtain the maximum power, it may be necessary to adjust the cams to suit the
characteristics of the engine. A trip down to your rolling road is the favourite way to obtain the best performance from
your engine.
8. There is no need for you to run the camshaft in, except for the first 25 miles. Do not exceed the normal running in procedure,
as recommended by the vehicle manufacturer.

 

[SkYwAlKeR]

good info........

 

[BLANk]

good info...thx bro!!!

 

[zurinazwan]

Camshaft Tips & Definitions

By UNDERGROUND4RACING.BLOGSPORT.COM
What cam grind is right for your street machine? We’ve compiled some basic tips and terms that can prove helpful in the camshaft selection department.
Tip 1: A low compression-ratio powerplant will respond favorably to a camshaft that features relatively short duration figures, wide lobe centers, rapid valve opening rates, and a high lift number (comparatively). On the opposite side of the coin, an engine that features a high static compression ratio easily can use more duration and tighter lobe centers.
Tip 2: Virtually all of the major cam grinders (and more than a few oil companies) discourage the use of synthetic oils during engine break-in--particularly on engines with flat tappet (solid or hydraulic) camshafts. Instead, use a quality grade of naturally formulated oil for the break-in. You can safely use synthetics following the proper break-in period. Besides, synthetics are pricey, and you’d have to drain it out after the first 20 minutes or so anyway.
Tip 3: Valvespring damper failure is more common that we’d like to think (especially on high-lift, radical-profile camshafts). Occasionally, a damper will physically "unwind" and the lower portion of the assembly will work its way between two lower coils of the outer spring. Naturally, this stacks the spring into coil bind. One easy solution to this problem is to inspect the spring, inner spring, and damper carefully before installation. You might find that some valvesprings have added "flashing" on the spring ends (this is quite common on some dampers). If that’s the case with your spring(s), use a small die grinder and very carefully smooth over the burrs. Similarly, some dampers have very sharp edges on the "flats." The life of the damper can be improved by gently deburring and chamfering this section.
Tip 4: Before sliding a set of larger-than-stock ratio rockers inside your Chevy (as an example, adding 1.6:1 rockers in place of 1.5:1 rockers), carefully check for coil bind at the valvespring, especially in applications with stock or stock spec valvesprings. You need at least 0.40-inch clearance between the springs at maximum lift.
Tip 5: When installing an aftermarket, high lift camshaft with stamped-steel, stud-mounted rockers, be sure to check the rocker arm slot that allows the rocker to pivot at maximum lift. There should be approximately 0.60 inch of additional travel left in this slot when the valve is at maximum lift. At the same time, be sure that the rocker arm contacts only the valve tip, not the valvespring or retainer.
Tip 6: In the area of single- and dual-pattern camshafts, controversy seems to reign supreme. Proponents of the dual-pattern grind feel that a standard pushrod engine will breathe better on the intake side than it does on the exhaust side. In this scenario, the exhaust lift and duration figures are greater in order to compensate for the exhaust port’s inability to breathe. The single-pattern group points out that the exhaust is somewhat controlled by cylinder pressure. The piston movement helps to force the exhaust from the combustion chamber and, as a result, the intake port does not have any real advantage. This makes for a single-pattern camshaft that features identical intake and exhaust lobe profiles. Which is the better of the two designs? Both have merit. Your particular combination might respond properly with a dual-pattern cam grind while a slightly different Chevrolet might show promising results with a single-pattern grind.
Tip 7: Piston-to-valve clearance should always be checked when a high lift cam is installed in an engine. It should be pointed out that high-lift figures alone do not always contribute to piston-to-valve clearance problems. Overlap and rod length also can create problems.
Very seldom is a specific valve fully open when the piston reaches top dead center (TDC) in a wide-lobe-center, short-overlap camshaft application. As the lobe-center angle is decreased, the proximity of the valve face to the piston dome is increased. In a narrow-lobe-center, long-overlap application, the valve remains open for a longer period of time as the piston approaches TDC. This problem is magnified when a powerplant is fitted with "long" connecting rods. As the rod ratio number increases (due to the longer-than-stock connecting rod), the piston remains at TDC longer, which can contribute to piston to valve-clearance problems.
Tip 8: If you bend one or more pushrods for no apparent reason, there’s a very good chance the engine is experiencing some form of mechanical interference in the valvetrain. The places to look include the rocker arm-to-stud clearance, valvespring coil bind, interference between the retainer and the valve seal or retainer, and the valve guide. In addition, high engine rpm might be causing the valves to whack the pistons, which in turn bends the pushrods.
Tip 9: Never overlook the fact that pushrods of the wrong length can wreak havoc on the rocker arm geometry, adversely affect the amount of lift, and even contribute to valve guide wear in the engine. A number of factors can influence pushrod length and valvetrain geometry. These include a decked block, installation of a smaller base circle cam, lash caps, non-stock-length lifters, or custom-length valves, and alteration of the valve seat depth. If any of these items have been included in your engine, then the pushrods could be far too short. To measure the correct pushrod length, try a set of adjustable measuring pushrods.
Tip 10: When a stamped-steel rocker arm bites the dust on a Chevy V8, it’s usually an exhaust rocker. Why? Simply because the exhaust side runs hotter. But when it comes time to replace the rockers, swap a good used intake to the exhaust side and install a new rocker on the intake. That way, the new rocker won’t be killed before it’s "seasoned." It’s just cheap insurance.
Definition: Theoretical valve lift is the figure often published in cam manufacturers’ specification charts and is the most common term used to describe the lift of the cam. Theoretical valve lift does not take into account valve lash, valvetrain deflection underload, variables in rocker arm ratio, and so on. Think of theoretical valve lift as maximum valve lift under ideal conditions.
Definition: Net valve lift is the real-world number that your particular powerplant experiences with all variables taken into account. Items such as valve lash, valvetrain deflection, and rocker arm ratio variation are considered when this particular measurement is determined. It should be pointed out that it is virtually impossible for any camshaft grinder to print a true "net" figure on its specification card. The only viable method of determining actual net valve lift is by setting up a dial indicator on the nose of the rocker arm and measuring the lift while the powerplant is in an "operational" mode (but, of course, not running).
Definition: Lobe lift or camshaft lift is the term that describes the amount of lift the camshaft provides without any benefit of rocker arm ratio multiplication factors. For example, a small-block Chevrolet roller camshaft may have an advertised lobe lift of 0.350. If the engine makes use of a standard 1.50:1 ratio rocker arm, the final theoretical valve lift works out to 0.525 (0.350 X 1.5). In the event that the powerplant uses a 1.60:1 ratio rocker arm, the theoretical valve lift works out to 0.560-inch. Think of cam lift as the true amount the camshaft lifts the valve lifter in the respective lifter bore.
Definition: Advertised duration is the most common form of listing specific duration figures. It is measured in crankshaft degrees and basically expresses the length of time that a given valve is open. Unfortunately, this particular figure can be more optimistic than theoretical valve lift. A good portion of the discrepancy regarding advertised duration figures is due to the fact that many manufacturers tend to include the camshaft lobe clearance ramp in their duration figures. For example, a Chevrolet ZL1 camshaft has an advertised duration figure of 359 degrees on the exhaust side. Obviously, this is an extremely stout number and, when you give it some consideration, you can clearly see that the powerplant could hardly run with such a radical camshaft. This is where 0.050-inch duration figures come into play. Measured with the 0.050-inch method, the very same ZL1 grind features a duration figure of 273 degrees. That’s a significant difference.
Definition: The 0.050-inch duration figure is determined when the valve lifter has risen 0.050-inch off the camshaft base circle (opening side) and closed to within 0.050-inch (closing side) on the ramp. This particular duration figure is quite accurate for comparison purposes and in most areas is much closer to true duration than the advertised number. Airflow in the intake or exhaust port is minimal at low lift figures, especially when the clearance ramp numbers are included in the discussion. Since this airflow is almost nil in most situations, the camshaft manufacturers began using the 0.050-inch method to determine a universal number that could be used for camshaft comparison. The newer 0.050-inch number is more accurate and can, at least, be compared without worrying about variables such as ramp clearance.
Definition: Several camshaft grinders have begun to use the 0.020-inch duration figure in addition to the previously mentioned 0.050-inch number. It is primarily a seat duration figure and most often is used to determine valve timing at the seat. This figure is helpful when plotting a specific cam profile on graph paper and also can be of some assistance when comparing various camshaft profiles.
Definition: Overlap was once a very common figure but, much like advertised duration, it has fallen from favor as a comparison tool among many cam grinders. Basically, overlap is the number of degrees that the camshaft features with both the intake and exhaust valves open simultaneously. Overlap takes place at the beginning of the intake stroke and also at the end of the exhaust stroke.
Definition: Lobe center is the amount of camshaft degrees between the point of maximum lift on the intake lobe and the point of maximum lift on the exhaust side of a given pair of cam lobes. As an example, lobe center is calculated for cylinder number one only and does not deviate between number one and the other cylinders in the powerplant. To make a representative sketch of lobe center, draw a line between the very center of a camshaft intake lobe and then draw a similar line through the respective exhaust lobe for the same cylinder. The number of camshaft degrees between these two imaginary lines is the camshaft lobe center.
Also called lobe displacement angle (LDA), the lobe center has a definite bearing on how a particular camshaft will operate in a specific powerplant. If the lobe center of the camshaft is increased, the valve overlap will be decreased. The overlap decrease is created because the exhaust timing will occur earlier and the intake timing event will occur later in relation to crankshaft position. Conversely, if the lobe center or displacement angle is decreased, overlap increases. Note that lobe center cannot be changed once a camshaft has been ground.
Definition: Lobe centerline should not be confused with lobe center or lobe displacement angle. The term "lobe centerline" refers to an imaginary line drawn through each respective lobe but does not combine the separation angle between the intake and exhaust lobes in a given pairing. Lobe centerline can be altered by advancing or retarding a camshaft, while lobe center is a figure that cannot be altered since it is incorporated into the camshaft when it is designed and manufactured.
Definition: A symmetrical camshaft makes use of the same profile on the opening and closing side of a specific lobe. In other words, the opening side of an intake lobe features a shape that is exactly the same on the closing side of the lobe. This term should not be confused with single-pattern or dual-pattern camshafts (see below).
Definition: An asymmetrical camshaft features a lobe shape or profile that is different on the opening side than the closing side of the same lobe. For example, a camshaft could feature a very rapid valve opening profile, but when the valve is closing on the same lobe, the shape could be extremely smooth and gentle.
Definition: Single-pattern camshaft grinds feature identical intake and exhaust lobe configurations. This actually means that the valve timing is the same for both the intake lobe and the exhaust lobe. It should be pointed out that a camshaft can be asymmetrical in design yet still be a single-pattern grind. On the other hand, a camshaft can be symmetrical yet also be a single-pattern configuration.
Definition: Dual-pattern camshaft grinds make use of different profiles on the intake and exhaust lobes. This means that the exhaust lobe and the intake lobe are not identical in shape. A cam profile of this type could feature an asymmetrical lobe on the intake and a symmetrical lobe on the exhaust. It also could be symmetrical in both, asymmetrical in both, or any combination of these types of profiles.

 

[zurinazwan]

[FONT=&quot]How to Degree Camshafts[/FONT]

By:UNDERGROUND4RACING.BLOGSPORT.COM
[FONT=&quot]we figured now would be a logical time to cover a camshaft basic. One of the keys to making power is to properly set camshaft timing; in other words, when valves open and close in relationship to the position of the piston and crankshaft is critical to the performance of the engine.
The process of properly setting the camshaft position is referred to as "degreeing the cam." Many beginner tuners mistakenly believe that to degree cams means setting the cam gears at a certain position such as "+1 intake and -2 exhaust." Though this information may be useful at times, these settings may not be accurate on all motors.
For example, when the deck of a head or block is machined, it will retard the cam timing. So the cam gear setting method may only apply to engines using the same type of cam gears with exact same head and block heights. This also assumes that the given cam gear settings are the correct location for the cams.
The most accurate way to set camshaft position is to properly degree the cams. This way you can be sure the cams are in the right position regardless of engine variations, deck heights, and cam gear marks. The method we are proposing is a simple way for setting cam positions using peak lift measurements. Cam degreeing can also be used to check valve opening and closing positions, durations at various lifts, and peak lift measurements.[/FONT]
[FONT=&quot]Helpful Tip 1[/FONT][FONT=&quot]
When degreeing a camshaft, make sure that you rotate the crankshaft in the direction the engine normally runs. If you over shoot the position the crankshaft is supposed to be in, do not rotate the engine backward. It will throw off your numbers because the tensioner only works properly in one direction.[/FONT]
[FONT=&quot]Step 1:[/FONT][FONT=&quot] Install a degree wheel onto the end of the crankshaft, and bolt a pointer onto the block. The pointer can be a sharpened piece of welding rod or coat hanger that can be bent to change the position of the pointer. Rotate the crankshaft to top dead center, or TDC, for piston no. 1. You can use a dial indicator inserted down the spark plug hole or the piston stop method; the piston stop method is more accurate. When the crankshaft is at TDC, move the pointer so it points to TDC/0 degree on the degree wheel.[/FONT]
[FONT=&quot]Step 2:[/FONT][FONT=&quot] Set up the dial indicator with the tip on the retainer, NOT the rocker arm. To get an accurate reading, it is important to make sure that the axis of the indicator is parallel with the axis of the valve. Make sure the rocker is on the base circle of the camshaft; in other words, make sure the valve is completely closed, and zero out the dial indicator. We recommend that you degree the cam with the lash set at 0.000-inch.[/FONT]
[FONT=&quot]Helpful Tip 2[/FONT][FONT=&quot]
If you are having a hard time finding the centerline because the cam dwells at peak lift, you can take a reading of the degree wheel when the cam reaches max lift less than 0.003 inch before and after peak lift. The middle of those two positions will be the centerline.[/FONT]
[FONT=&quot]Step 3:[/FONT][FONT=&quot] Rotate the crankshaft. When the cam starts to open the valve, the dial indicator will show the amount of valve lift. Rotate the crankshaft and stop when the pointer is pointing at the specified peak lift/center line position. Loosen the cam gear bolts and rotate the camshaft until the indicator is showing that the cam is at peak lift. Tighten the cam gear bolts. Rotate the engine two more rotations, stopping when the dial indicator reaches peak lift, look down at the degree wheel to make sure the position of the crankshaft is in the correct location. If not, repeat step 3.[/FONT]
[FONT=&quot]Step 4:[/FONT][FONT=&quot] Move the dial indicator to the other side of the head, and repeat steps 2 and 3. When peak lift positions of both the intake and exhaust cams are set in the proper locations, the cams are considered to be degreed in.[/FONT]
[FONT=&quot]CAMSHAFT DEFINITIONS[/FONT][FONT=&quot]
When discussing camshafts, enthusiasts often get confused with the terminology used to describe the various parts of the camshaft. This diagram and these definitions should help most people better understand camshafts and their related terminology.[/FONT]
[FONT=&quot]Ramp[/FONT][FONT=&quot]
The textbook definition of ramp is the section of the cam from the base circle to where the valve physically begins to open, or finishes closing. It is also commonly referred to as a clearance ramp; or in other words, the part of the cam lobe where the camshaft will close up the initial tappet clearance (lash) and the tappet/follower will make initial contact (on the opening side) or end its contact with the camshaft (on the closing side). Skunk2 defines ramp as the portion of the profile from the base circle to the point of maximum valve acceleration. Skunk2's Fast Ramp Technology helps the valve go from zero to maximum acceleration as quickly as possible and still maintain superior valvetrain stability.[/FONT]
[FONT=&quot]Flank[/FONT][FONT=&quot]
This is defined as the end of the ramp section to the point where the valve reaches maximum velocity. We frequently hear people talk about "aggressive ramps" when they are actually trying to describe the flank and how quickly the valve is opening. It is important to find the balance between opening the valve too quickly and not opening the valve quick enough. If the valve is not opened quick enough, "area under the lift curve," the airflow is not optimized. If the valve is opened too quickly the camshaft may run off the tappet, and it will become difficult to slow the valve down enough as it goes over the nose.[/FONT]
[FONT=&quot]Nose[/FONT][FONT=&quot]
Nose is defined as the section between the maximum velocity on the opening side and maximum velocity on the closed side, or rather the section of the cam where the valve spring forces are keeping the valvetrain from separating from the cam surface. Controlling valve accelerations over the nose is critical to preventing valve float and high-rpm valvetrain stability. Skunk2 Amax Technology allows the company to design the flank and nose section of the cam to maximize area under the curve and still maintain valvetrain stability.:hmmmm:[/FONT]

 

[zurinazwan]

Camshaft Timing by :UNDERGROUND4RACING.BLOGSPOT.COM
As with ignition timing, accurate valve timing, or cam timing as some people refer to it, is critical for achieving maximum horse power delivery from your engine. The first thing you need to accurately set your cam timing is a timing degree wheel, or a cam timing disc, that you can get from your camshaft manufacturer. You also need a dial gauge with a magnetic stand to find true top dead center (TDC) of the no. 1 cylinder and the correct valve lift, and an adjustable vernier gear.

It is easiest to set the cam timing before the cylinder head is fitted to the engine. You need to accurately determine TDC using the dial gauge and accurately mark TDC on the crankshaft pulley. Usually, the car manufacturer would mark TDC on the crankshaft pulley, but you should verify that it is marked accurately as if it is even just a few degrees out, it can have a significant effect on power delivery. Accurately marking TDC on the crankshaft pulley will also be helpful when want to check or adjust the cam timing at a later stage, with the engine fully assembled and fitted.
The next step is to bolt the cam timing degree wheel to the crankshaft, fit a temporary pointer to the engine block and set the pointer to TDC or 0° on the cam timing degree wheel. Then fit the cylinder head and install the camshaft, or camshafts if it's a twin-cam cylinder head. The engine should be at TDC and at the end of the compression stroke on the no. 1 cylinder, so the camshafts should be installed with the intake and exhaust valves of the no. 1 cylinder closed.
The camshaft manufacturer or grinder will provide you with a specified valve lift and the point at which that valve lift for the intake valves and the exhaust valves should be achieved. This may be for full-lift, or a specified amount of valve lift with the valve opening. Also, the point at which the valve lift is achieved is measured in degrees of crankshaft rotation, which is why we bolted the timing degree wheel to the crankshaft. Our next step is to attach the dial gauge to the cylinder head, with the stylus on the intake valve of the no. 1 cylinder and zero the dial gauge. Now rotate the crankshaft to the specified point at which the specified valve lift should be achieved and read the amount of valve lift off the dial gauge. If it is not the same as the valve lift specified by the manufacturer, then free up the vernier gear and turn the camshaft until the correct valve height is achieved. Take care not to let the valves hit the crown of the piston while you're doing this adjustment as the valves could bend quite easily. With the specified valve lift of the intake valve occurring at the specified degrees of crankshaft rotation, tighten up the vernier gear. Your intake valve timing is now set. On a single-cam cylinder head you just need to verify that the exhaust valve also reaches the specified valve lift at the specified point. But on a twin-cam cylinder head you will need to set your exhaust valve timing by repeat this process for the exhaust valve of the no. 1 cylinder.
It's quite easy in theory, but a bit more complicated if you need to determine the exact point that full-lift is achieved and the same applies to determining TDC accurately.
FINDING TDC

Finding TDC accurately is a bit complicated as the piston is stationary at its apex for a few degrees of crankshaft rotation. Thus assuming that TDC has been reached when the piston is at its apex is not accurate enough when you want to set cam timing. This is where the dial gauge and the timing degree wheel come in quite handily. Bolt the degree wheel to the crankshaft, fit a temporary pointer to the engine and place the dial gauge on the engine block with the stylus the no. 1 piston. Determine when the piston is at its apex and zero the dial gauge. Now rotate the crankshaft until the piston is a short distance, say ¼ inch or 5 mm, below its apex. Mark this point on the degree wheel. Now turn the crankshaft in the opposite direction until the piston is at the same distance below its apex and mark this point on the degree wheel. True TDC would be the mid-point between the two marks on the degree wheel.
FINDING FULL VALVE LIFT

The same technique can be used to determine when the camshaft reaches full valve lift. The toe of the camshaft lobe is shaped to keep the valves at full lift for as long as possible, which is usually a good number of degrees. If you need to find full lift as your reference point when setting your cam timing, you need to find the exact point of full valve lift. Start with the engine at TDC. Then turn the crankshaft back until the camshaft lobe acting on the intake valve of the no. 1 cylinder is pointing more or less upward and the intake valve is fully closed. Set up the dial gauge with the stylus on the valve retainer cap of the intake valve and zero the dial gauge. Now rotate the crankshaft until the intake valve opens and is a short distance, say 0.1 inch or 0.25 mm, past full lift. Mark this point on the degree wheel. Then turn the crankshaft in the opposite direction and stop when the intake valve starts to close and is at the same distance from full lift. Mark this point on the degree wheel. Needless to say, the point of full lift for the intake valve would be the mid-point between the two marks on the degree wheel. Now you just need to repeat this process to find the point of full lift for the exhaust valve. :hmmmm:

 

[sg x]

so frm the info u r telling us cam such as powerzone ,matspeed or others is trustable or nt
confusing or u juz simply paste....

 

[zurinazwan]

if u like u can use ....i give u info or ready,u can think it`s ok 4 u setting or not.....TEPUK DADA TANYA SELERA...CAU........

 

[zurinazwan]

up date my thread on 3/11/2008 c u soon