How do I calculate difference in .004 to .006 Adv Dur in a cam
06-16-2006, 04:52 AM
#1
Staging Lane
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How do I calculate difference in .004 to .006 Adv Dur in a cam Have tryed this Q in Advanced tech with no responces.
I am looking at some large stroker cams and specificaly there Advertised duration, some are at .004 as in the crane cams and .006 in the Comp lobes. I am using a DCR calculator thats only accurate for .006 does anyone know what the difference is between .004 to .006. How can I work out what the Crane cam will be at .006 so I can use its .006 in the calculator, any help would be great.
example,
Cam 1. Comp
@.006" @.050"
In 301---251
Ex 305---255
Cam 2. Crane
@.004 @.050"
In 314---250
Ex 322---258
I am looking at some large stroker cams and specificaly there Advertised duration, some are at .004 as in the crane cams and .006 in the Comp lobes. I am using a DCR calculator thats only accurate for .006 does anyone know what the difference is between .004 to .006. How can I work out what the Crane cam will be at .006 so I can use its .006 in the calculator, any help would be great.
example,
Cam 1. Comp
@.006" @.050"
In 301---251
Ex 305---255
Cam 2. Crane
@.004 @.050"
In 314---250
Ex 322---258
06-16-2006, 05:13 AM
#2
Do you know where these are measured? I believe Crane uses Tappet movement, not sure about Comp. But if they use valve movement, using the standard SBC rocker ratio of 1.5 would make them the same measurement. David Vizard talks about this in his valve train book.
06-16-2006, 08:13 AM
#3
Staging Lane
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thanks, this is for a LS1 408 stroker. The crane is at the tappet .004, I need to know how to calculate or add a figure to .004 to get it to .006 then put that figure to the calculator as it works out from a fixed Adv Dur of .006. The two cams I gave in the examples have Advertised Durations measured at different points one measured at .004 and another at .006, I cant use the Adv Dur of the Crane cam of 314 and 322 @.004 in the calculator as it will give me an inacurate DCR. what will the 314/322 be at .006 not at .004
thanks, my head hurts.
thanks, my head hurts.
06-16-2006, 01:04 PM
#5
Without knowing the lobe speed, it's hard to say. Each cam will vary depending on the ramp it's on. Your Crane cams are on softer lobes, so the IVC will be later causing less DCR. More aggressive dictates a sooner IVC and more DCR, less aggressive has a later IVC and less DCR. If your looking to go more aggressive, don't use the Crane lobes.
