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LS3 heads...Blue springs?

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Old 08-03-2011, 11:39 PM   #1
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Question LS3 heads...Blue springs?

Bought a set of ls3 heads parts # 12629063. Just got them opened the box and was suprised to see blue spings on them. Are these also good for a .570 lift cam or are they diferent. GMPP catalog says they come with ls6 springs, is this a replacement for the "yellow" springs?
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Old 08-04-2011, 07:18 AM   #2
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Yup, GM switched from yellow to blue.
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Old 08-04-2011, 07:26 AM   #3
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Are you guys sure that the "yellow" springs will do .570 lift on an LS3 head? I remember on the LS6 heads they were rated for that, but all the literature for the LS3 heads that I've seen specifies .525 lift... I assume due to the larger, heavier valve compared to the LS6 heads.
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Old 08-04-2011, 11:15 AM   #4
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Several factors come into play during spring selection, beyond the cam's lift value. The ramp rate, valve weight, intended RPM range, etc...all are critical in picking the right spring.
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Old 08-04-2011, 11:20 AM   #5
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...but all the literature for the LS3 heads that I've seen specifies .525 lift... I assume due to the larger, heavier valve compared to the LS6 heads.
The factory LS3 cam is 0.551" lift.
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Old 08-04-2011, 11:43 AM   #6
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So if I use the blue springs from the ls3 heads on my 5.3 with a ls6 cam it'll work
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Old 08-04-2011, 02:01 PM   #7
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The factory LS3 cam is 0.551" lift.
Only the 430hp ls3 is .551 lift. The crate ct 525and 376/515 is .525, the lsa is .492 the gm hot cam is .525. ls3376/480 is .525

The springs are rated for .570 lift but only use the .525/.492/.551 in those particular engines. Kind of a one spring fits all deal.
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Old 08-09-2011, 10:30 PM   #8
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I think you can only use LS3 heads on 4" or larger bore? 5.3l is 3.89" bore? Check your bore before installing.
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Old 08-09-2011, 10:58 PM   #9
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Yes the heads will not fit on a 5.3... The bore has to be 4.000 or bigger
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Old 08-10-2011, 01:50 AM   #10
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Yes the heads will not fit on a 5.3... The bore has to be 4.000 or bigger
THIS!
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Old 08-10-2011, 05:06 AM   #11
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The blues are the same IH and coil bind as the yellows, with a little more seat and open pressure GM switched to them mid 2011 MY
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12629063, 525, blue, ct, head, heads, l92, ls, ls1tech, ls3, ls6, spring, springs, valve, yellow

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