IC - Valve & Ignition Timing (in brief)

Ic Engine-Valve Timing and Ignition Timing | Classle

hole is normal........it is provided to drain any rain water that accidently enter exhaust....

@prince: O...ok

i want you to guide me regarding the improvement obtained from such a method.
i understand the longer duration cam will keep the valves open for a longer time, but the ports and the valves being stock, and the pull of air from the TDC back to stroke 0 also being the same, what is actually increasing the performance ?

If it intakes more air, then the compression should increase right ? (correct me if i am wrong)
Or is it that the smoother air intake, which helps the bike climb revs faster ?

Does it really give us a worthy increase in performance ?

Let me try to answer this.

Analogy - The time you keep the water tap open determines the amount the bucket will fill. This is valid even if the water pressure remains the same.

I think you got it. The air pressure before ignition will increase, yes. But the compression ratio remains the same.

@ ncg (nano cool genius)

I hope this would almost clear some basic doubts of us all here

From Yahoo....

"What do performance camshafts do, and what all is involved in installing one?"

"well an engine is a modified pump. It's efficiency is based on how much power it can move in and out of it. The more an engine can flow in and out the more power it will make. More oxygen in air plus more fuel equals more power. So aftermarket camshafts alter the duration and lift. Longer duration and more lift to get more air into the cylinder to make more power. You are increasing volumetric effiency and usually you should have a intake, better manifold and throttle body to take advantage of increased airflow. I would also recomend better valves, retainers, and valve springs while you are in there for further performance gains

You will need to take off the valve cover and expose the valve train. Make sure you are at TDC. You might have to take off the distributor depending on the application, the timing belt will need to be loosened and moved off the sprockets. The camshaft retaining parts need to be taken off then the camshafts should just pull out with the sprocket gears. Usually when you change cams it is a good idea to buy adjustable cam gears to change valve timing. Then go reverse putting them in, making sure everything is in line. I would suggest a good mechanic as well. It is a good idea to buy a piggy back ecu to adjust the fuel and timing to make power and get some dyno time with an experienced tuner."


From HOWSTUFFWORKS


" The camshaft uses lobes (called cams) that push against the valves to open them as the camshaft rotates; springs on the valves return them to their closed position. This is a critical job, and can have a great impact on an engine's performance at different speeds."

"The key parts of any camshaft are the lobes. As the camshaft spins, the lobes open and close the intake and exhaust valves in time with the motion of the piston. It turns out that there is a direct relationship between the shape of the cam lobes and the way the engine performs in different speed ranges.

To understand why this is the case, imagine that we are running an engine extremely slowly -- at just 10 or 20 revolutions per minute (RPM) -- so that it takes the piston a couple of seconds to complete a cycle. It would be impossible to actually run a normal engine this slowly, but let's imagine that we could. At this slow speed, we would want cam lobes shaped so that:

Just as the piston starts moving downward in the intake stroke (called top dead center, or TDC), the intake valve would open. The intake valve would close right as the piston bottoms out.
The exhaust valve would open right as the piston bottoms out (called bottom dead center, or BDC) at the end of the combustion stroke, and would close as the piston completes the exhaust stroke.
This setup would work really well for the engine as long as it ran at this very slow speed. But what happens if you increase the RPM?"
When you increase the RPM, the 10 to 20 RPM configuration for the camshaft does not work well. If the engine is running at 4,000 RPM, the valves are opening and closing 2,000 times every minute, or 33 times every second. At these speeds, the piston is moving very quickly, so the air/fuel mixture rushing into the cylinder is moving very quickly as well.

When the intake valve opens and the piston starts its intake stroke, the air/fuel mixture in the intake runner starts to accelerate into the cylinder. By the time the piston reaches the bottom of its intake stroke, the air/fuel is moving at a pretty high speed. If we were to slam the intake valve shut, all of that air/fuel would come to a stop and not enter the cylinder. By leaving the intake valve open a little longer, the momentum of the fast-moving air/fuel continues to force air/fuel into the cylinder as the piston starts its compression stroke. So the faster the engine goes, the faster the air/fuel moves, and the longer we want the intake valve to stay open. We also want the valve to open wider at higher speeds -- this parameter, called valve lift, is governed by the cam lobe profile.

Any given camshaft will be perfect only at one engine speed. At every other engine speed, the engine won't perform to its full potential. A fixed camshaft is, therefore, always a compromise. This is why carmakers have developed schemes to vary the cam profile as the engine speed changes.

This Link shows an animation how a regular cam and a performance cam have different valve timing. Notice that the exhaust (red circle) and intake (blue circle) cycles overlap a lot more on the performance cam. Because of this, cars with this type of cam tend to run very roughly at idle.
HowStuffWorks "How Camshafts Work" (Check this for animation)

Single Overhead Cam
This arrangement denotes an engine with one cam per head. So if it is an inline 4-cylinder or inline 6-cylinder engine, it will have one cam; if it is a V-6 or V-8, it will have two cams (one for each head).

The cam actuates rocker arms that press down on the valves, opening them. Springs return the valves to their closed position. These springs have to be very strong because at high engine speeds, the valves are pushed down very quickly, and it is the springs that keep the valves in contact with the rocker arms. If the springs were not strong enough, the valves might come away from the rocker arms and snap back. This is an undesirable situation that would result in extra wear on the cams and rocker arms.


Check this out for picture and animations..
HowStuffWorks "Camshaft Configurations"

Selecting your camshaft

From NEWMANCAMS

Phases 1 to 5 will help select the camshaft that
meets our requirements.

PHASE 1 (PH1) ROAD CAMSHAFT (I Think our p220F camshaft on p180 can be considered in this category when compared to stock camshafts)
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.

Installation of the camshaft

1.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.

2. Rotate the engine by hand and ensure that the valves miss the pistons and block by 0.060/1.5mm

3. 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.

4. Before starting the engine, remove spark plugs and spin the engine up until the oil pressure is indicated.

5. Ensure that the cam being fitted is identical to the unit being replaced, except for the cam profiles

6. Set the camshafts up on the timings supplied on the data sheet (Will i get one with the p220f one). 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 4 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

7. 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

" I have read somewhere about camshaft running-in procedure on cars, where it says, engine should be set running at 2000rpm for 20 minutes and never should be allowed to idle at 1500rpm. Though small variations in the range near 2000rpm is advisable..
I think this would suit the running-in procedure for our conversion to 220F camshaft, and there it mentioned proper and complete greasing of the camshaft... can someone tell me as to what kind of grease to be used and where it would be availabl in chennai? "

For more information on materials a camshaft uses, check

cam

So much info on cams....good..... the ignition on cams is taking place at the correct timing The most important things to remember are: 1. Valve timing 2. Valve lift. 3. Valve lift duration. 4. Valves overlap. Hope this starts and integrate more info....

psr guru i plan to go for the 220F valve clearance hope that would do...
and are valve timing and the timing chain the same (i sound myself silly...), how do we set it..?

is it like setting to TDC opening the head... and what is the next step, heard that itz a simple job by matching the markings...
where do i find these markings.... is it to be set straight by rotating the wheels?

The Crank shaft drives the Timing Chain and the cam.The cam with it's relative position to the Crankshaft,and hence Piston position ,actuates the valves for correct inlet and exhaust.
Setting the correct Cam position is through aligning the Cam sprocket markings with the flywheel magneto markings at TDC...or as described in the workshop service manual.
The Pulsar Manuals are available in PDF form and you can download it for reference.

keep the valve clearances the same as for a regular 180 as the cam doesn't open the valves any more than the stock one ,if you want to set the valve clearences yourself get a feeler gauge having the smallest dimensions as there is hardly any space inside the ports to use a regular one (i tried....),
as for the exact differences b/w a high lift and longer duration camshaft try this link

Thanks Guru n KB...

what grease should i be using on the camshaft? what is the specification?

Guys one doubt..

Thanks Guru n KB...

One more thing what grease should i be using on the camshaft? what is the specification?

What would be the difference if i went between 180 Valve clearance and 220's, wouldnt i be experience a more kick in the use of the new camshaft in terms of power because of the new change in timing, or would the compression be high? <am confused here, how can the compression increase with an increase in valve clearance, infact wouldnt it bring a more relaxed delivery of power with a relaxed compression>

Increase in VC can also be done on stock engines right!!? provided we are knowledgeable enough to implement a new timing...and that would bring correct compression or proper complete combustion. Am i right?
if so the same would be the case here right!!?, Higher VC would compensate the increase in compression brought by the new camshaft bringing more usable power....
or am i going stupid?..
If am right which would be logical the 200's valve clearance or 220's, will the local mechanics have these gauges ?

If am right, would mileage be the reason why bajaj didnt try this out?

Ya...GURU, Samarth just reminded me, i have the service manual with me... will go through it

Now am looking for all tools that my 180 or to be moded 180 would demand, both would be same right!!??

@moderators.... Can you please rename the thread head to
" Issues faced on my Pulsar180UG3 and upgrading it to p180ug3 version 2 "

I think this would be the ideal topic since i had faced jetting/tuning issues with stock filter & K&N, and at a later stage found clutch and tappets to be the issue makers ... Now a new mod has been started... so the current topic holds nowhere in this stage...