farmington

iTrader: (14)

I'm assuming that all of the yellow valve springs on 243 heads are the LS6 type of springs. What motors got the yellow springs? I know that some truck motors got 243 heads, will they have the yellow springs too? Or are they just used on car motors? Do all 243 castings have the same valve sizes? Trucks too?

johnLs1camaro

iTrader: (28)

i wanna say the trucks and ls2 motors will show a 799 casting which is the same as the 243.

Darkman

iTrader: (2)

243s come on LS6 and some LS2s (e.g. LS2 CTS-V 2006-2007).

Brand GM Performance
Manufacturer's Part Number 12586484
Valve Spring, Beehive, 90 lbs. @ 1.8 in., 295 lbs @ 1.250 in., .570 in. Maximum Lift, LS6/LS2,
Product Line GM Performance LS6 Valve Springs
Number of Springs Per Valve Single
Outside Diameter of Outer Spring (in) 1.290 in.
Coil Bind Height (in) 1.085 in.
Damper Spring Included No
Spring Rate (lbs/in) 375 lbs./in.
Inside Diameter of Outer Spring (in) 0.885 in.
Valve Spring Style Beehive
Coated No

89 formula350

iTrader: (8)

i finally get to say this.... the same question gets asked at least once a week

ZeeOSix

Don't use the yellow springs ... 2002 and 2003 LS6s have had early OEM valve spring failures. Get a set of PAC 1518s and sleep good at night.

farmington

iTrader: (14)

Guess if it gets asked so often it must have a sticky somewhere. Just bought a set that has the yellow springs and wanted to know something about them, sorry to inconvenience you.

89 formula350

iTrader: (8)

no biggie just giving ya a hard time is all.

farmington

iTrader: (14)

I thought that when I was doing the Mopar thing, there were a lot of pompous jerks on those sites. Guess the LS1 sites aren't immune. Pity.

Zerokube

iTrader: (4)

and the search (option) will set you free...

itsslow98

iTrader: (18)

Go back to the Mopar thing then, otherwise learn to use like elementary kids can do.

vettenuts

iTrader: (4)

My 09 Silverado 5.3 has the 243 heads as well. Not sure on the springs as the valve covers have never been off. The "yellow" springs were updated (still yellow) a few years back due to some of the failures that have occurred and the newer ones that have been coming through are now blue.

The real question is what are you doing with the springs? They likely won't control the valve train with any type of aftermarket cam.

LS1121

iTrader: (17)

I was always told "If you don't have anything Good to say don't say anything"

Bilster

iTrader: (21)

Does anyone know if the valve sizes for the truck 243's are the same size as the Z06
243's?

Darkman

iTrader: (2)

Yes, all 243s have the same valve sizes (from the factory, of course).

Detoxx03

iTrader: (14)

I always hear this but whats the deal with sodium filled valves? I'm looking for some 243's and don't want to buy something I shouldn't. Did they also come on the TBSS's? over

Darkman

iTrader: (2)

Certain 243s that originate on some LS6s come with hollow-stem intake valves and exhaust valves that are filled with 78% potassium/22% sodium aka sodium-filled valves. These valves are lighter in weight. They are also slightly longer (0.6mm) than their standard counterparts in order to allow the LS6, which has a smaller base circle cam, to use a standard pushrod. These lightweight valves are getting harder to find and are more expensive.

Even with some 243s having the light weight valves, all 243s use intake valves with a 2.00-inch diameter and an 8mm stem as well as an exhaust valves with a 1.50-inch diameter and an 8mm stem.

So the valves, standard and lightweight are interchangeable even though running a mixture of the two types would presumably require different length pushrods.

PREDATOR-Z

Why?
It is the small cam base circle that will dictate p-rod length (if both on stock lifters), not the length of the valves. Geometry is done via rocker shimming.

Darkman

iTrader: (2)

Got it. Thanks.

ZeeOSix

If you mixed valves, and one valve was 0.060 longer than the other when using the same cam & rocker arms, then the the pushrod lengths would have to be different to give the same lifter pre-load distance. A longer vavle will decrease the distance from lifter to rocker arm (ie, pushrod length). There are no rocker shims used in a factory stock LSx engine that I know of.