All things being equal is there a difference in idle from .56x lift to 58x lift?
04-03-2003, 02:03 PM
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Re: All things being equal is there a difference in idle from .56x lift to 58x lift? Wouldn't it change a little? With the higher lift you should be getting more intake and exhaust overlap (not a longer duration, but more flow for the same duration)than the lower lift = more lope.
Is this correct?
Is this correct?
04-03-2003, 02:11 PM
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Re: All things being equal is there a difference in idle from .56x lift to 58x lift? Remember, duration is amount of degrees at a lift point.
Duration numbers we throw around here is degrees at .050".
Increased lift always increases duration at some lift point.
Possible for the .580" lift cam to have sam duration at .050" and same exact overlap.
Duration numbers we throw around here is degrees at .050".
Increased lift always increases duration at some lift point.
Possible for the .580" lift cam to have sam duration at .050" and same exact overlap.
04-03-2003, 05:52 PM
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Re: All things being equal is there a difference in idle from .56x lift to 58x lift? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by HP-GURU:
<strong>Possible for the .580" lift cam to have sam duration at .050" and same exact overlap. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">If you are comparing Comp cams that are the same duration at 0.050", but one is about 0.58 and the other 0.56, the 0.58 actually has less advertised duration. So I'd have to say that a comp 0.58 lobe will have less overlap than a similar comp 0.56 lobe, and hence will idle better.
<strong>Possible for the .580" lift cam to have sam duration at .050" and same exact overlap. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">If you are comparing Comp cams that are the same duration at 0.050", but one is about 0.58 and the other 0.56, the 0.58 actually has less advertised duration. So I'd have to say that a comp 0.58 lobe will have less overlap than a similar comp 0.56 lobe, and hence will idle better.
04-03-2003, 06:20 PM
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Re: All things being equal is there a difference in idle from .56x lift to 58x lift? Miles,
What you said is it depends on the lobe.
Overlap is not a bad thing either.
Dennis
What you said is it depends on the lobe.
Overlap is not a bad thing either.
Dennis
04-04-2003, 01:25 AM
#7
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Re: All things being equal is there a difference in idle from .56x lift to 58x lift? The diff between .560 and .580 lift is so freakin' insignificant in terms of overlap that you'd never notice the difference, IMO. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
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04-04-2003, 01:32 AM
#8
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Re: All things being equal is there a difference in idle from .56x lift to 58x lift? I'm with the Colonel on this one. If you have the ears of a fricken barn owl and you can distinguish the minor difference in the flush of air caused by the slight difference in the lift of the valves through a set of headers, down a y-pipe, into the collector and out the *** end, then I'll be damned! Either that or you're a crack addict and you're hearing things.
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<small>[ April 04, 2003, 01:35 AM: Message edited by: derty ]</small>
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<small>[ April 04, 2003, 01:35 AM: Message edited by: derty ]</small>
04-04-2003, 10:52 AM
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Re: All things being equal is there a difference in idle from .56x lift to 58x lift? If you take a comp cam lobe that has 216@.050 and has .538" lift, the advertised duration is 265*. Now take a comp cam lobe that has 216@.050" and has .560ish lift, the advertised duration goes up to 270*, so you will have slightly more overlap, therfore the idle will be a little rougher. The confusing thing is that its not the lift that made it have a rougher idle, it was the increased overlap. The cam needs to start opening the valve faster, sooner to get it up that extra 20 or so thousandths. Regardless, the difference will be minimal as far as idle goes. Hope this makes sense lol
04-04-2003, 05:49 PM
#10
Re: All things being equal is there a difference in idle from .56x lift to 58x lift? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Colonel:
<strong> The diff between .560 and .580 lift is so freakin' insignificant in terms of overlap that you'd never notice the difference, IMO. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Right, 20 thousandths of an inch is about the thickness of a busness card, not a very significant percentage of a half-inch.
<strong> The diff between .560 and .580 lift is so freakin' insignificant in terms of overlap that you'd never notice the difference, IMO. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Right, 20 thousandths of an inch is about the thickness of a busness card, not a very significant percentage of a half-inch.
