Ls3 valve springs

TrendSetter

TrendSetter

Organ donor in training
Re: Ls3 valve springs

i did a quick search and heres some info. it was kind of what i figured about the difference in valve stem od.

You cannot use LS3 spring retainers and locks because they are designed for 8mm O.D. LS valve stems and SB Chevy valve stems are 11/32" O.D. You must use Comp Cams SB Chevy retainers and locks designed for 11/32" O.D. valve stems that are designed for beehive valve springs. Comp Cams 795 retainers and 613 locks are 10 degree and are a perfect fit on the LS3 beehive valve springs.

The LS3 beehive valve springs coil bind at 1.085". That means if you set up the LS3 valve springs at 1.700 @ 128 lb. seat pressure using SB Chevy valves, the maximum valve lift will be is .555" with a .060" safety margin. You must have at least .600" clearance between the bottom of the SB Chevy retainers and the valve seals with the valves on the seats. Mock up each valve with only a retainer and locks and measure them during the valve job. That will tell you how much material you must machine from the top of the valve guide boss when you machine each boss for the positive stop Viton seals. You must machine each valve guide boss diameter approximately .065" or to .835" O.D. The LS3 valve springs are .845" I.D. The valve guide boss serves as a valve spring register in order to prevent spring oscilation. If you allow beehive valve springs dance around on the seats, you will have broken beehive valve springs just below the retainers.
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Rob2000gt

Rob2000gt

Donating Member
Re: Ls3 valve springs

The reason I ask is because we have a bunch of ls3 take offs with less than 10 miles on them I hate to see them sit and not be used
 
TrendSetter

TrendSetter

Organ donor in training
Re: Ls3 valve springs

i searched for ls3 springs on sbc. the 4.3 is just a 350 missing a couple cylinders so the valvetrain is the same.

i have a set of 0 mile ls3 springs also but havent found a use yet since boost requires a little better spring.
 
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