Valve Timing Points - Advance or Retard?
06-23-2003, 07:29 AM
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Valve Timing Points - Advance or Retard? Since valve openings and closings are the real numbers to be concerned with. What are your points? Mine are; -1 BTDC, 39 ABDC, 51 BBDC, -9 ATDC.. I have heard that the ABDC Intake closure was a critical point and an "optimized" point range was 42-45(?) for the LS1.. is this correct? If this is so, then would I be advancing or retarding my cam from 39 -> 43???
06-23-2003, 02:28 PM
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Re: Valve Timing Points - Advance or Retard? Just because the 42-45 intake closing point is "ideal" doesnt mean that you should change your setup points to meet that. It depends on what you are doing w/ your car. Having the intake valve close earlier provides more low rpm torque. But if you want to get your IVCP to be in that range, you'll have to retard your cam about 4 degrees w/ an adjustable timing set.
06-23-2003, 09:09 PM
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Re: Valve Timing Points - Advance or Retard? Appreciate the reply Brad..
Do I understand correctly that I would retard the cam 4 deg to have the IVCP close earlier increasing low end? That is exactly what I want to do, and I'm also confirming what the DYNO 2000 is showing me.. I just didn't want to retard the cam without justification.
Do I understand correctly that I would retard the cam 4 deg to have the IVCP close earlier increasing low end? That is exactly what I want to do, and I'm also confirming what the DYNO 2000 is showing me.. I just didn't want to retard the cam without justification.
06-24-2003, 03:38 PM
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Re: Valve Timing Points - Advance or Retard? Hey Zatlanta....
Brad is correct. Yes....you'll gain some low end tq., but at the expense of higher shift points to achieve peak hp. I thought you wanted to keep the peak #'s lower in the RPM range
Retarding that cam 4* is gonna move your peak #'s up higher, you'll be shifting ~ 600-800 rpm's or so higher than if you went straight up....yer call 
Brad is correct. Yes....you'll gain some low end tq., but at the expense of higher shift points to achieve peak hp. I thought you wanted to keep the peak #'s lower in the RPM range
Retarding that cam 4* is gonna move your peak #'s up higher, you'll be shifting ~ 600-800 rpm's or so higher than if you went straight up....yer call
06-24-2003, 04:41 PM
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Re: Valve Timing Points - Advance or Retard? My understanding is that when you advance a cam, you increase the low end. Retard the cam and you increase top end. Therefore, retarding the cam 4 deg so the IVC occurs at 43 deg is what you are after.
BTW, I too have been messing around with DYNO 2000. I find it hard to believe that retarding the cam can return so much more power that it claims. Anybody out there tested it out yet?
BTW, I too have been messing around with DYNO 2000. I find it hard to believe that retarding the cam can return so much more power that it claims. Anybody out there tested it out yet?
06-25-2003, 08:23 AM
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Re: Valve Timing Points - Advance or Retard? Mike,
Thats just the trade off I'm looking at.. I think I'd like to keep the torque "level" and have a good power ramp throughout the rpm band. As it looks straight-up, I'll be peaking at around 5000 (which is OK for me) but both torque & hp really drop off beyond that with my cam. If I was seeing an "increase" in tq/hp midrange then.. but retarding the timing seems to stretch that tq/hp level furthur..
Thats just the trade off I'm looking at.. I think I'd like to keep the torque "level" and have a good power ramp throughout the rpm band. As it looks straight-up, I'll be peaking at around 5000 (which is OK for me) but both torque & hp really drop off beyond that with my cam. If I was seeing an "increase" in tq/hp midrange then.. but retarding the timing seems to stretch that tq/hp level furthur..
