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Location:
Townsville
Registered:
August 2005
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What are Cam Gears?
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Wed, 19 October 2005 04:50
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Hey I am new to the car mod scene and I was wondering wat Cam Gears are and how the improve the performance of the engine. any help would be appreciated.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Location:
Hobart, Tas
Registered:
May 2002
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Re: What are Cam Gears?
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Wed, 19 October 2005 05:16
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Go to www.google.com and type in "cam gears".
This sounds harsh, but... seriously. You can find out what they are yourself first, and then ask questions.
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I supported Toymods
Location:
melbourne
Registered:
June 2002
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Re: What are Cam Gears?
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Wed, 19 October 2005 05:57
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its kinda one of those things, if you dont know what they are, you dont need them.
Stick to the traditional formula, the solution solves the problem, and not the other way around.
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Location:
Melburn!
Registered:
June 2005
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Re: What are Cam Gears?
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Wed, 19 October 2005 07:04
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Cam gears are the gears that drive your cams. You can get adjustable ones which allow you to "dial in" your cams to get them just the way you want them. I am sure someone will correct me if I am wrong.
However I am fucking amazed that people are bothered to post up "do a search" and wont even give a little information, I mean fuck that was two sentances.
Cheers
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Location:
brisbane
Registered:
September 2005
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Re: What are Cam Gears?
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Wed, 19 October 2005 07:50
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i agree with windex
sure tell them to search, but its a bit rude not to atleast give this dude a clue...comeon fellas
~andrew~
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: What are Cam Gears?
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Wed, 19 October 2005 07:56
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| love ke70 wrote on Wed, 19 October 2005 17:50 |
i agree with windex
sure tell them to search, but its a bit rude not to atleast give this dude a clue...comeon fellas
~andrew~
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click first link of search i posted first
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Location:
Oakleigh, Melbourne
Registered:
March 2004
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Re: What are Cam Gears?
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Wed, 19 October 2005 07:56
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Considering it's a car forum and was not a another bloody 4A-GE question.
Dude, there was an article in SPEED magazine, maybe issue 17? correct me if im wrong but thats how i found exactly how adj cams work and how can be utilized to our performance needs.
-Jay
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: What are Cam Gears?
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Wed, 19 October 2005 08:05
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| Windex wrote on Wed, 19 October 2005 17:04 |
However I am fucking amazed that people are bothered to post up "do a search" and wont even give a little information, I mean fuck that was two sentances.
Cheers
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5th link of search i posted.. and not a bad write up.
http://www.sportcompactcarweb.com/insidetechnology /0208scc_insidetechnology01a/
the beef people have is:
-this is a site for modification of cars and engines, not Auto-101 class.
-if someone doesn't even have the initiative to do a search for something so basic, what hope do they have of successfully modifying things?
-there's a big difference between having no clue... and having no clue but prepared to look for information by themselves....
if someone posted up a question like "what is a spark plug, what does it do?" how would you feel? how would you feel after answering the same question 10 times.... or 20? after a while people get frustrated at the increasing inability of newcomers to, not just ignore looking at old threads, but to completely fail to look anywhere on the internet for BASIC INFORMATION.
yes i realise i have spent more time writing this then directly answering question.. but i answered the question in one line by opening op many avenues for the dude to look for himself...
spoon feeding does not make an intelligent modder 
Cya, Stewart
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: What are Cam Gears?
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Wed, 19 October 2005 08:07
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| Quote: |
Making Sense of Cam Gears
By Larry Saavedra
Let's take the math out the complex operation of the camshaft.
One of the most popular advances in product development for do-it-yourself tuners is adjustable cam gears. They are engineered to make precise cam timing changes as easy as turning a wrench.
Prior to these little aluminum gears, cam timing changes meant hours of labor "keying" the fixed cam gear and guess work to change cam timing. Fast forward to the new age of technology.
The need for adjustable cam gears are many, namely a reliable, precise and affordable method of fine-tuning the action of the valves to complement the installation of performance add-ons (headers, cams, intakes) or specialty milling work on built engines.
While adjustable cam gear installations are fairly straightforward, there's always going to be (and rightfully so) heated discussion as to their effectiveness and construction.
We spent a considerable amount of time surfing the web to uncover some of what people were saying, and we learned that cam gear slippage is a major concern among end-users. Slippage refers to the bolts loosening up and allowing the cam timing to advance or retard fully often with catastrophic results. It is typically related to the fasteners that attach the inner hub to the outer gear sector not being set to the proper torque. For whatever reason, particular cam gear manufacturers were singled out for their alleged shortcomings in this area, and so when we discovered that Advanced Engine Management took extra measures to upgrade their fasteners, it perked our interest.
Avoiding Slippage
Developed from the need to accommodate customers that did not have the proper tool to torque their Allen-head cam gear adjustment bolts to manufacturerﾂ痴 specs, AEM came to the rescue by producing its cam gears with proven Grade 8 hex head bolts.
"We've changed our cam gear bolts to accommodate AEM customers who make regular changes to their cam gears," stated AEM chief engineer John Concialdi.
"The new bolts are easier to properly tighten to the required 15 lbs/ft of torque. They also have an integral washer flange for greater load distribution," he added.
Another explanation on how this improves the product might be realized in the following equation:
Torque = force x length of lever
Or in the classic sense:
Weight x Arm = moment
For example, if you apply 100 lbs of force on a one-foot long bar, the lbs/ft of torque applied would be 100. If you applied 100 lbs of force on a two-foot bar, the lbs/ft of torque would equal 200, and so on.
With their old Allen bolts, if the customer was to use a standard Allen wrench with a six-inch handle, he/she would have to apply 30 lbs of force...and it's not easy to apply 30 lbs of force on a little wrench like that. That's just a lot of pressure for such a short moment arm. Inevitably, their bolts were not being tightened to the recommended specs, and in some cases they would eventually loosen, causing the gears to slip.
This was not a design error. The old Allen bolts are just as reliable the hex head bolts. The difference is that most people own standard sockets and now have no excuse for not torquing down these bolts as per the recommended specs. After all, it is much easier to apply 15 lbs of force on a one-foot ratchet handle than it is to apply 30 lbs of force on a skinny, six-inch Allen wrench handle.
It should be noted that one of the positive byproducts is that these bolts do stand up better to repeated adjustments than the Allen bolts did, simply because Allen bolts are more likely to strip in the hex over time and socket type tools are more durable than hex keys.
And so with that understood, let's continue with our lesson in how everything works.
Basically, the job of the camshaft is to open and close the intake and exhaust valves at the "proper time" relative to engine position (piston travel) - to charge the combustion chamber and expel burnt gasses.
However, once you've bolted on performance parts, milled the head or installed a lumpy performance cam, you also alter the optimum cam timing that most sport compacts prefer. What can you do?
By changing the cam timing (retard, advance/overlap), we tune the overall drivability and performance aspect of the car. Even stock engines can benefit by dialing-in cam timing/overlap. These are typical variances in production tolerances that when fine-tuned to your particular engine set-up will easily produce added power.
Many factory cams operate on the conservative side of performance due to emissions and drivability standards, meaning there's always more power to be gained by learning how-to adjust the intake and exhaust valve timing.
Just as aftermarket engine management systems manage precise ignition timing, adjustable cam gears allow you to govern the action of the cam, which controls the timing action of the valves to shift peak power points or to tweak timing overlap within the engine cycle. "Overlap" is the point in the cam's cycle where the intake and exhaust valves are open simultaneously. Here's where critical tuning really optimizes performance because you are producing the most efficient charge of air/fuel in and out of the combustion chamber.
In racing, the ability to dial-in ignition and cam timing/overlap for different track conditions can mean the difference between winning and losing a race. Autocross enthusiasts rely on low to mid-range power for tight turns, whereas drag racers need all the power at the top end. This applies to setting up a car for mostly city or highway driving. In either case, adjustable cam gears will optimize the peak power curve so that maximum performance is adjusted to your style of driving.
While the aftermarket is ripe with adjustable cam gears, don't assume that all cam gears are the same. Variations in material, design, anodizing, and other engineering deviations can affect quality.
Also don't assume that by using adjustable cam gears you have free-reign when changing valve events (that could be catastrophic if the exhaust cam is retarded too much for example). Rather, having firsthand knowledge of how timing effects the cam's operation is key to successfully fine-tuning your engine.
It's important to note that adjustable cam gears have no direct effect on the duration and lift of the valves, that's the job of the camshaft lobes (profile) as dictated by the cam manufacturer.
Think of adjustable cam gears this way:
If the intake valves open at 10 degrees before top dead center (TDC) and close at 190 degrees after TDC, the total duration is 200 degrees. The opening and closing times can be shifted with adjustable cam gears to rotate the cam ahead a little as it spins. For example, if we advance the intake cam 5 degrees then the inlet valves would open 5 degrees earlier. The intake open timing would shift to 15 degrees BTDC and the intake valve would also close earlier by the same 5 degrees. In the example above, the valve timing would be IO at 15 degrees BTDC and IC at 185 degrees ABDC. With SOHC engines the cam timing events for intake and exhaust occur together so intake and exhaust events move the same amount. Retarding timing works just the opposite.
On a SOHC engine, an adjustable cam gear will allow you to move the power curve to a specific area in the rpm band as described above. Like moving your peak power on a high-revving Honda to max out at 4000 to 5000 rpm. Typically to improve bottom end power advancing a SOHC engine will do the trick and the converse is true to enhance top end power.
On DOHC engines you can dial-in intake and exhaust timing independently of each other to regulate overlap. As you'll start to see, combined with the use of a chassis dyno you can fine-tune your cam's entire operation by advancing or retarding its action, squeezing as much horsepower and torque from your state-of-tune as possible.
We decided to dyno a late model DOHC Civic using a set of AEM's new improved cam gears to see how much effect they had on performance. This particular Civic had lots of high-performance parts on it already, including a big turbo, so what we were trying to achieve was an optimum peak power curve for a forced-induction vehicle.
As we mentioned, cam gear slippage can be catastrophic to the valve train, so before we got started, we inspected AEM's new Grade 8 hex head bolts that lock the gear to the camshaft.
The new bolts also have an integral washer flange for greater load distribution. They have also improved the hard anodized surface on the outer gear sector for better wear resistance. Independent testing indicates that the new anodizing is 30 percent more resistant to wear.
Once we were satisfied at what we saw, we proceeded to install the new cam gears. AEM Tru-Time adjustable cam gears are manufactured and assembled in the USA and are CNC-machined from a billet extrusion of 6061 T-6 billet aluminum. AEM's gears are adjustable up to 10 degrees advance or retard in one-degree increments via precise laser-engraved indication marks.
We set ignition timing to 20 degrees advance, and proceeded to dial in both the intake and exhaust side of the cam gears in that order.
For us drivability means more than "peak power" numbers. We were looking for what lies under the power curve, and that's area we attempting to improve upon, which we finally did.
In order isolate the effects of making the changes to the cam timing, the ignition timing has to be reset whenever the intake cam timing was changed.
This is because the intake cam drives the distributor and when the cam is moved the ignition timing moves with it. We adjusted the ignition timing to be the same regardless of cam timing. Also we did the changes to the intake and exhaust cams independently until the end of the test to demonstrate the effects of the changes of each cam. By doing this, we were able to see which trend might gain power for us without having to test the cam timing changes in all possible permutations.
In the end we asked tuner veteran John Concialdi to comment on the outcome. His comments are written below each power run chart.
Horsepower
Torque
BASELINE RUN
(Ignition Timing Set to 20 Degrees Advance/Cam Timing Zero)
RPM Peak HP Peak Torque
7500 253.0 177.2
Baseline run in as received condition.
Intake Cam Gear 3 Degrees Advance
(Ignition Timing Set to 20 Degrees Advance)
RPM Peak HP Peak Torque
7250 252.0 183.0
Power is up through the drivable portion of the graph. The only point where the power was hurt is in an area where most cars are not used in. Advancing the Intake cam closes the intake valve-closing event earlier than intended and on cars with relatively long inlet runners such as those on most production cars can hurt the power. The column of air in these manifolds has a lot of inertial energy to "ram" the air in well beyond BDC. This means that air continues to fill the cylinder even though the piston is on its way back up the cylinder. Closing the inlet valve earlier in this case negated the positive effect of the inertial energy in the inlet column. In the case of this car we were using a Type R manifold, which has somewhat short runners so the effect of using the inertial energy in the manifold was negated. In fact there appears to be a positive effect of closing the inlet valve sooner, which may be attributed to the fact that the inlet charge may have been partially wasted in the overlap event due to excessive blow down of the inlet charge.
Intake Cam Gear 3 Degrees Retarded
(Ignition Timing Set to 20 Degrees Advance)
RPM Peak HP Peak Torque
7500 252.5 177.0
Power is down throughout the entire power band. Closing the inlet valve sometimes helps by having the valve open longer to take advantage of the energy in the inlet column. For the reasons mentioned above this didn't work in our case.
Exhaust Cam Gear 3 Degrees Advanced
(Ignition Timing Set to 20 Degrees Advance)
RPM Peak HP Peak Torque
7250 256.0 185.4
THAT really killed the power in the important part of the RPM band! The area where we gained power (6750 - 7500) is useless in my opinion. First off we cut down the overlap by doing this. A second effect was that the boost decreased a little along with this change. Closing the exhaust valve too early mitigated the effects of blow through. The loss of blow through also helped reduce some after burn in the exhaust port, which contributed toward the reduction in boost. This obviously was a bad move unless the engine is to be operated in the 6500 - 8000 rpm range exclusively.
Exhaust Cam Gear 3 Degrees Retarded
(Ignition Timing Set to 20 Degrees Advance)
RPM Peak HP Peak Torque
7500 253.6 177.6
That got the power close to the intake advanced 3 degrees setting again but didn't quite match it. This change increased the overlap by closing and opening the exhaust valve later. The opening of the exhaust valve later may have not allowed the piston enough time to drive out the gasses effectively and diluted the subsequent inlet charge.
Exhaust Retarded 3 Degrees, Intake Retarded 3 Degrees
(Ignition Timing Set to 20 Degrees Advance)
RPM Peak HP Peak Torque
7750 250.6 170.0
Here we effectively leave the overlap the same but move the valve events to a later time. This is the second best change in terms of power in the useable power band but still does not match the Intake advanced position.
Exhaust Retarded 3 Degrees, Intake Retarded 1 Degree
(Ignition Timing Set to 20 Degrees Advance)
RPM Peak HP Peak Torque
7750 253.3 171.6
We just advanced the intake cam 2 degrees but still had a net of 1 degree retard on the intake cam. This was third best and helped top end power a little but not enough to give up the bottom end advantage afforded by advancing the intake cam.
We did not try advancing the exhaust cam in conjunction with advancing the intake cam because of the big power loss that occurred with advancing the exhaust cam on its own.
For everyday use I would use the intake at 3 degrees advanced position. Keep in mind that the TOTAL engine set up dictates where the cam timing should be for a particular use. Inlet manifold design, exhaust system cam grind etc. have a profound effect on where the cam timing produces power
This is why cam tuning is best done on the dyno where the results can be quantified.
For more information about AEM's cam gear, click the link below.
Read the Details
Sidebar: Abrasion Testing
To verify the quality of AEM's anodized cam gear surfaces, we asked an independent testing lab to apply a Taber Abrasion Test to the product. This test measures the amount of material loss of the anodizing in milligrams/1000 cycles of an abrasive wheel.
There are cam gears used in the performance aftermarket with various surface treatments applied to the outer gear sector to prevent wear or corrosion. These are:
Type 1 Anodize usually used in applications where appearance is important. Type 1 Anodize comes in a variety of colors and looks great. Unfortunately it has poor wear characteristics.
Dyed Hard anodize is the typical hard anodizing found in many automotive applications where wear is a problem. Many pulleys and belt drive systems use dyed hard anodizing. The dye used to color the anodizing does not degrade the hardness, but the sealer used to keep the color in the anodize reduces the hardness by up to as much as 40%.
Natural Hard anodize is the hardest of the hard anodizing processes. The lack of dye in the anodizing means that there has to be no sealing process done therefore there is no reduction in hardness.
These tests were conducted at an independent testing laboratory and the results are listed in softest to hardest order of anodizing. The test procedure used was, Federal Std. 141 Method 6192.1, ASTM #D-4060.
Type 1: red Sample #1 20.6 Mg/1K cycles
Sample #2 20.3 Mg/1K cycles
Average 20.5 Mg/1K cycles
Dyed Black Sample #1 2.7 Mg/1K cycles
Sample #2 2.6 Mg/1K cycles
Average 2.65 Mg/1K cycles
Natural Sample #1 1.7 Mg/1K cycles
Sample #2 1.9 Mg/1K cycles
Average 1.8 Mg/1K cycles
The conclusion? Our lab tests showed that the natural color of the anodizing used by AEM results in the maximum hardness available, as indicated by its lower numbers.
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amazing how would have thought this was on da intahnet
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Location:
brisbane
Registered:
September 2005
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Re: What are Cam Gears?
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Thu, 20 October 2005 06:40
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point made stewart 
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Location:
Sydney
Registered:
September 2004
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Re: What are Cam Gears?
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Thu, 20 October 2005 09:53
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stewarts gone postal!!!
good write up tho 
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: What are Cam Gears?
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Thu, 20 October 2005 10:03
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no wuckign fay in hell i'd write that for someone who couldn't search..
is just cut and paste from link No.5 from the search i initially posted....
finding info on teh intahnet is far too easy, but no-one seems to bother these days... 
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: What are Cam Gears?
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Thu, 20 October 2005 10:28
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Doesn't anyone call them by their correct name of cam pulleys any more ... ?
(They aren't gears)
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I supported Toymods
Location:
melbourne
Registered:
June 2002
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Re: What are Cam Gears?
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Thu, 20 October 2005 10:35
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you mean calling them adjustable cam pulleys? (or sprockets in the case of a certain tractor/truck motor)
interestingly enough, i sent an email to the author of 21st century performance, explaining the difference between slide adjustable and vernier adjustable cam gears, (as he had labelled a picture quite wrongly) he never wrote back to me!
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Location:
Sydney
Registered:
February 2003
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Re: What are Cam Gears?
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Thu, 20 October 2005 10:35
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can i call them sprockets?
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I supported Toymods
Location:
melbourne
Registered:
June 2002
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Re: What are Cam Gears?
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Thu, 20 October 2005 10:43
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not unless they are driven by a chain
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