Retarding timing w/nitrous... which one?
07-19-2001, 12:54 PM
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Car: 2002 SOM z28
Engine: LS1
Transmission: T-56
Retarding timing w/nitrous... which one?
So with a 150HP (or whatever) shot, they say to retard the timing between 2-4 degrees... fine.
Which part of the timing is the most crucial to this? I mean, for those of us with an adjustible vacuum canister and a good spring kit, which is the one that you should spend the most time thinking about? I am assuming the rate of advance and the overall advance are probably more important the the base timing.
It would be a lot more convenient to simply turn the vac can a few turns at the track and reduce the rate of advance, then to reduce the base timing and adjust the idle speed and all that goes with it.
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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...
-=ICON Motorsports=-
Which part of the timing is the most crucial to this? I mean, for those of us with an adjustible vacuum canister and a good spring kit, which is the one that you should spend the most time thinking about? I am assuming the rate of advance and the overall advance are probably more important the the base timing.
It would be a lot more convenient to simply turn the vac can a few turns at the track and reduce the rate of advance, then to reduce the base timing and adjust the idle speed and all that goes with it.
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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...
-=ICON Motorsports=-
07-19-2001, 05:17 PM
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The vacuum can only adds advance at part throttle not at full throttle where you will be using your nitrous. You will have to pull out some base timing. The best soultion is to use a retard box of some sort.
07-19-2001, 06:38 PM
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Car: 2002 SOM z28
Engine: LS1
Transmission: T-56
Why do I need to pull out base timing? What you said about it only on at WOT would make sense that the overall timing is the issue, well at least between 2000-5000 rpms (when I flip on the nitrous with a window switch). If that is the case, could you not just reduce the amount of mechanical advance by adding stiffer springs in the HEI? Or is the rate of advance say through 1500-3200 rpms (just picking a range for illustration purposes) is the only important time and the timing under 1500 or above 3500 rpms is not a factor?
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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...
-=ICON Motorsports=-
------------------
1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...
-=ICON Motorsports=-
07-22-2001, 07:17 PM
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I don't know what curve your distributor has but I have full advance at 2800RPM about where my nitrous fires. If your mechanical advance is slower than this then yes you can control detonation by changing it. But in my car from 2800RPM I have full advance and so it is the base timing that I have to pull.
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