Retard the Cam Timing?
#1
Three Wheelin'
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So while I was pulling my car apart to replace the head gasket last night, I noticed that the camshaft timing mark was off by one tooth. When the motor was at TDC, the mark on the cam sprocket was one tooth back of the mark on the housing. Is there an advantage to retarding the cam timing? Should I align it back up to the way it should be when I reassemble it? How much retard is this...5 degrees?
#4
Rennlist Member
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Has anyone ever done any dyno comparisons to see if there is a high-end performance gain for retarding the cam timing by a tooth (or a partial tooth)?
(One tooth is 9 degrees on the cam shaft.)
(One tooth is 9 degrees on the cam shaft.)
#5
Nordschleife Master
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+/- 1 degree altered my power output by almost 10% at the same boost level so small changes can do very much. I would definately recommend doing the adjustments on the dyno, it's hard to notice the effect on the street/track.
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#8
Nordschleife Master
#10
Nordschleife Master
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Also, my experience isn't that adjusting the cam gear just moves the powerband up/down. It can actually bring more power to the table without losses in another region.
Look at this dynochart. This is cam gear adjustments ONLY!
Look at this dynochart. This is cam gear adjustments ONLY!
![](http://www.revline.se/cars/RRXXX/2009/revlinecamgear_plusminus1deg.jpg)
#11
Rennlist Member
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So what do the colours correspond to Duke? Which lines are more and which are less cam timing?
#12
Nordschleife Master
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In this case blue was at 0, red 1 deg retarded and green 1 deg advanced.
But it can be different on different engines depending on how much the head has been resurfaced etc.
As you can see, it really starts to make a difference after 6000 rpm.
But it can be different on different engines depending on how much the head has been resurfaced etc.
As you can see, it really starts to make a difference after 6000 rpm.
#14
Nordschleife Master
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Yes.
Remember that this is pretty modified engine so you don't get the same results as on a stock engine.
This is with a very large turbo and it spooled over 500 rpm later on the Rototest than on the street. With a small turbo that spooled at 3000 rpm and more stock stuff the curves would have looked differently.
That engine setup is for top end power so a retarded cam does not yield the same results as on a stock midrange engine.
It really is a system that's why is so important to do a custom tune and setup for modified engines to be sure you get the most out of it.
Remember that this is pretty modified engine so you don't get the same results as on a stock engine.
This is with a very large turbo and it spooled over 500 rpm later on the Rototest than on the street. With a small turbo that spooled at 3000 rpm and more stock stuff the curves would have looked differently.
That engine setup is for top end power so a retarded cam does not yield the same results as on a stock midrange engine.
It really is a system that's why is so important to do a custom tune and setup for modified engines to be sure you get the most out of it.
#15
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+/- 1 deg. of the actual cam shaft? Or is that the cam relative to the crank shaft angle? Meaning 1 deg crank is actually 0.5 deg on the cam.
I would assume actual cam, but I have seen people reference cam timing relative to crank angle, so just wanted to confirm.
Thanks,
I would assume actual cam, but I have seen people reference cam timing relative to crank angle, so just wanted to confirm.
Thanks,