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Is it better to advance or retard when doing your timing chain
#41
03-18-2008 | 05:02 PM
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Joined: Feb 2006
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From: Richmond, Va
RE: Is it better to advance or retard when doing your timing chain
Anybody read up on the new VVT sytems? Sounds like that may be the bomb. Apparently, it advances and retardsvalve timing depending on power or economy requirements dictated by an ecu.
That is interesting about the older Rams having less retard ground in than the newer models. I wonder if that was part of thier whole bstorque management/go easy on the plenum gasket strategy. I agree with rabbler. If your just playing around with it, without really knowing where you are to begin with, then it is a roll of the dice. If you can find the exact specs for your year/engine, then you can probably bank on them. I have heard of very few computerized grinds being off, especially new grinds, but you still don't 'really' know unless you do the tedious stuff.
This is a pretty straight forward read on valve timing:
http://www.compcams.com/Technical/TimingTutorial/
That is interesting about the older Rams having less retard ground in than the newer models. I wonder if that was part of thier whole bstorque management/go easy on the plenum gasket strategy. I agree with rabbler. If your just playing around with it, without really knowing where you are to begin with, then it is a roll of the dice. If you can find the exact specs for your year/engine, then you can probably bank on them. I have heard of very few computerized grinds being off, especially new grinds, but you still don't 'really' know unless you do the tedious stuff.
This is a pretty straight forward read on valve timing:
http://www.compcams.com/Technical/TimingTutorial/
#42
03-18-2008 | 05:28 PM
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Joined: Jul 2007
Posts: 1,488
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RE: Is it better to advance or retard when doing your timing chain
Some of the VVT or adjustable cam systems are pretty advanced and offer some pretty exiting enhancements.
It's interesting that some of the single cam systems (GM V6, and I6) only advance the cam and never retard. Other dual cam systems (Ecotec) can advance and retard each cam independently and vary not just cam timing but valve overlap as well. Combine that with at tunable intake manifoldand you can get a vary smooth idle and still have a very wide power band. Better fuel economy is a bonus too!
On thing I'm surprised we haven't seen (at least I've never seen any info on it) is a solenoid operated valve. Eliminate the cam shaft entirely. Theoretically you could have an infinitely adjustable system. Imagine if you could adjust valve timing, lift, duration and overlap all without changing any hard parts.
It's interesting that some of the single cam systems (GM V6, and I6) only advance the cam and never retard. Other dual cam systems (Ecotec) can advance and retard each cam independently and vary not just cam timing but valve overlap as well. Combine that with at tunable intake manifoldand you can get a vary smooth idle and still have a very wide power band. Better fuel economy is a bonus too!
On thing I'm surprised we haven't seen (at least I've never seen any info on it) is a solenoid operated valve. Eliminate the cam shaft entirely. Theoretically you could have an infinitely adjustable system. Imagine if you could adjust valve timing, lift, duration and overlap all without changing any hard parts.
#43
03-18-2008 | 08:23 PM
Record Breaker
Joined: Feb 2006
Posts: 1,567
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From: Richmond, Va
RE: Is it better to advance or retard when doing your timing chain
I'll bet it's a question ofreliability, size, and power draw. They'd have to be pretty heavy duty solenoidsto pull against springs that would close fast enough and if one ever failed at high rpms... well, you know that story. I was reading about dohc systems that could operate independently, butkind of got lost in it. Less beernext time maybe.Who knows, one day each cylinder could have it's own coil pack/ignition timing, valve timing, airflow sensor/damper,and wideband o2 or egtsensor. It would eliminate the need for a throttle body all together, and the throttle will be some kind of variable resistance wired directly to the computer. My son can have fun figuring all that sht out.
