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Discussion Starter #1
Hi,
Has anybody measured the valve spring pressure of an ’02 LS6? The springs are PN 12565313. The springs I got from Chevy don’t measure to their published specs in the ’02 shop manual. :-?

Here is a comparison of the spring data at .551” ~ the LS6 intake lift.
Seat 1.800” / open 1.249”
‘02 LS6 seat /open: 90/294 (@.551) rate: 370 (Chevy spec)
‘02 LS6 seat/open: 90/282 (@.551) rate: 350 (measured)

Here are some other well known springs for a comparison.
Crane 144830-16: 80/278 (@.551) rate: 360 (catalog)
Comp Cams 26915: 105/277 (@.551) rate: 313 (catalog)
Comp Cams 26918: 130/302 (@.551) rate: 313 (catalog)

Thanks for your help,
Steve
 

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Hi there, Steve,
Your measurements are within GM specs, allowing for given tolerancing from measuring equipment, while measuring a given seat pressure.
I would agree that they are a little on the lower side, however, you are still within a 5% tolerance.
Besttoyou, c4c5:eek2:
 

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Discussion Starter #3
Hi,
Thanks for the info. I see that the open pressure is within 5% of the rating. I wish it was 5% HIGHER then the rating. The only tolerance spec I have in the Chevy manual is: “Replace the LS6 spring if the spring tension is less than 400N (90 lb) at 45.75 mm (1.80).” These springs are already at that minimum and my expectation is that they will take a “set” and loss 5 lbs or so in the first 500 miles. This says to me, that I need to shim these springs on the first install ~0.020” (~7 lbs).

I have a calibration spring coming from Comp Cams next week to cal the spring tester. We have tested many other springs on this rig and they have always been close to spec. I will do this and see if the numbers get better.

Thanks for your help,
Steve
 
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