Every engine and every customer is different. Some setups are geared for crazy piles of screaming top end power. Others are looking for piles of mid range grunt. Either way, one thing is clear- there is no one setup that will perfectly satisfy everyone. That's the reason why adjustable parts were invented in the first place. Now, dialing in camshafts to a specific camshaft center line angle (CLA) is a daunting task best left for the experts. However, that doesn't need to deter you from tweaking your setup to get the most out of it. With a little simple dyno or logging work, and one of our adjustable cam gears you can fairly quickly dial in some great results with any camshaft set.
In this article we test out 3 different cam gear settings on a built 2 liter stroker 1.8T engine. It is using a Precision Turbo 5857 CEA turbocharger, our IECVA1 camshafts, and our IECHVA4 assembled CNC ported cylinder head. As you can see, this engine makes a good deal of power even at a moderate boost level of 22 psi, however we were able to find significant increases in the mid range and spool with some simple cam gear tweaks.
Step 1 Install the adjustable cam gear following all torque specifications with it at the baseline / 0 degree setting. Do a few dyno pulls or logs to get a base line. If you are logging, you can look at the MAF reading (grams/second) or the roadspeed acceleration rate to determine power increases. Here is our baseline pull, a real screamer with an awesomely flat torque curve.
Step 2 With the baseline map finished, prepare to adjust your cam gear. Begin by setting the engine to TDC (top dead center). Align the cam gear timing mark with the mark on the valve cover. Make sure the adjustable cam gear is also in the center line position.
Step 3 Verify TDC by checking that the timing marks on the crank damper and timing cover are properly aligned.
Step 4 The cam gear adjusts by loosening the five ARP cam gear center bolts. Use a 5/16" 12 point socket and loosen all the bolts by hand.
Step 5 Once all five cam gear center bolts are loose, use a breaker bar to slowly turn the crank by hand, doing so will rotate the cam gear outer ring. Turn the crank clockwise to retard timing, counter clockwise to advance timing.
Step 6 Verify using the cam gear timing marks to make sure you have the desired retard/advance. We began by retarding the timing by 2 degrees.
Step 7 Hand tighten the five cam gear bolts. Do not torque them in this step.
Use a confirmed torque wrench that has not been dropped, set to 14 ftlbs.
Tighten all five cam gear bolts to 14 ftlbs. Verify the cam gear center did not move during this step.
Step 8 Take another log with your new cam timing retard. This setting hurt power throughout the powerband and only was roughly equal to the original setting right in the very high rpm range. Clearly, this is not what we want. So, the next logical step is to try again adjusting in the other direction, by advancing the cam 2 degrees from it's original setting.
Step 9 Here we have done exactly that, we advanced the cam set 2 degrees from its original setting. While we lost a few horsepower after 9000 rpms, the engine spooled faster, and picked up quite a bit of torque and power throughout the mid range. There is no question that this engine would be faster on the street or even on the track with this setting.
Step 10 Now that you have a good idea what the engine is asking for, try adjusting it further in that direction until an optimum power curve is reached. This just takes some time, doing some dyno pulls or logs and building up some data so you can tell when you are where you want to be. As you can see from the dyno chart below, for a few hundred bucks in parts this modification- more a fine tuning of what you already have- can really be worth while. Since it is merely optimizing the parts you already have, it is worth the time to explore this option on any engine that is significantly altered from stock, as the original camshaft settings are not going to be optimized for your particular setup.
Here is an overlay of all 3 of our logs. Take note of the retard/advance changes in the power curve.