Sunday, October 27, 2013

Car Modification: All you need to know about Cam Pulleys


Wanted to fine tune your cam and have no idea on what to be done first. Here I compiled some of the information that you may needed in order to get everything done. First of all, you need to know that stock cam pulleys cannot be adjusted. Hence for you to tune your power/torque band, you must need to get an aftermarket adjustable cam pulleys.

However, one might think of why there is a need to adjust the cam pulleys since factory tuned should be the best of all in term of power and reliability. My answer is NO! Different timing is needed for different speed of engine to get the most efficient combustion.The cam pulley can be adjusted to suit the driving style of the driver. The powerband of the engine can be shifted by varying the timing of the valve. After understanding the useful thing provided by adjusting the cam pulley and let's go through how to choose a cam pulley by continue reading...

How to choose an Adjustable Cam Pulley
Firstly, get those made by light material (anodized billet aluminum) thus there is no valvetrain mass added. Secondly, those come with good cam gear bolts which have the ability to hold down the cam gears to prevent them from slipping. The cam gear should be rigid or surface-hardened enough to prevent the bolt from sinking into the cam gear surface. Thirdly, has marking engraved, clearly readable and easy to understand. Try not to get painted markings as they are easily worn off.

After you purchased the cam pulleys and is time to bring them over to install into your car and get them tune. You can either tune on the street or dyno machine. Try to time using a stopwatch if you do not have a data-logger that help to record speed and elapsed time. Do some wide open throttle acceleration runs at the 1/4 mile strip on a tune day.

For every cam gear setting, you are recommended to do your timing over the exact same road with the same distance. Run 2 times for every setting and measure the acceleration time. This is able to tell you if the setting is good for your engine. Acceleration is the change in speed over the change in time. You want a higher number if the cam gear setting is good. A change of 1 tenth of a second or more consistently is good. (Don't rely on some experts "butt dyno". It is only sensitive to changes during the early rpm range).  For the start of your tuning, it is recommended to go for 2 cam shaft degrees for the intake cam. Since it is also determines the reference baseline ignition timing as well.
Till the time you stop seeing any improvement in the elapsed time, then you may need to go back to the best setting you had done previously. After you had done, remember to reset your ignition timing back to your initial setting by using an ignition timing light.



PRECAUTION
A lot of people tend to ask for the best cam gear setting from the others. Nevertheless this is not recommended as similar models do not give you the similar performance even both cars have the same performance parts installed. Variations in performance can occur simply from minor differences in assembly at the factory, engine break-in procedures by the owner, and owner maintenance.

Regarding cam gear tuning, advance the intake cam gear and retard the exhaust cam gear too much, there is a risk that the piston will has contact with the valve. Do remember, 1 cam gear degree equivalent to 2 crankshaft degrees.









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2 comments :

Hi Firdaus,

Yes, however it is more difficult to get the most optimize setup for SOHC than DOHC due to it shares the intake and exhaust on a single cam.


Ben