5.7stroker

iTrader: (36)

Is this enough spring for a hydraulic roller cam taking these factors into account:

823 heads
Valve weights are 88g intake and 91g exhaust
Rocker arms - stock LS3 with CHE trunnions
Lifters - Johnson 2116LSR
Push rods 3/32 .080 wall
Cam/Valve Lift/Accelerations - 235/243 | .635”/.613” | LSA116.5+6..... no idea on accelerations, LS cams are similar.
Desired Max RPM - 7300

Spring specs are as follows:

155 lbs @ 1.780"
380 lbs @ 1.180"
400 lbs @ 1.130"
Coil bind @ 1.070"

So

Installed height when closed = 1.780
Seat pressure at installed height = 155
Calculated spring rate = 377
Height when spring is open = 1.130
Open pressure @0.65 lift = 400

So with the valve lift on cam of .635, if these are shimmed within .050 of coil bind wouldn't that be a 1.755 install height?

Install hieght of 1.780 - coil bind 1.07 = .730
.730 - .635 lift = .095.
To take the springs to .050 would require an install height of 1.755 because
1.78 - (((1.78 - 1.070) -.635) -0.050) = 1.755
1.070 +.050 = 1.120 +.635 = 1.755

The spring seat pressure at 1.755 install height would then be 164
And the open pressure at 1.755 installed height would be 409

(377/1000)*1000*(1.755-1.780) = -9.43 less spring pressure at the new installed height
155 - (-9.43) = 164 at the seat
((1.78-1.755)*377)+400 = 409 open pressure

LS1Formulation

iTrader: (13)

You literally are talking about my LS3 setup, and yes, it's good to go. You don't need to shim them, either. I shift at 7100 RPM and my rev limiter is set at 7400. My cam is 233/25X on a 113 LSA, .636/.636 lift. BTR Platinums with Ti retainers, which looks to be the springs you're considering by the specs.

5.7stroker

iTrader: (36)

The spring kit I believe is a SK001 with chromoly steel retainers. Not sure how these compare to tool steel?
BTR makes SK702 and SK703 also I see.

SK702: 170 lbs @ 1.800" 200 lbs @ 1.700" 380 lbs @ 1.180" Coil bind @ 1.000"
SK703 450 lbs @ 1.115 500 lbs @ 1.050" Coil bind @ 1.000"

I read that springs should be shimmed .050-.060 from coil bind which is what was confusing me.

LS1Formulation

iTrader: (13)

If the springs you have are appropriate for your cam, you shouldn't need to shim them. As far as I know, shimming them is to cut down on spring surge, but a dual spring setup shouldn't experience that much because the inner and outer springs will reach resonant frequency at different RPMs, which should cancel out any surging. I'm no expert, however.

Bob570

You should be fine I would think. My Camaro had no signs of valve float at 7000 rpm with a 109g intake valve with TSP .660 springs and titanium retainers.

5.7stroker

iTrader: (36)

I thought I had searched well enough. Apparently not lol. Post #6, back in 2016...

https://ls1tech.com/forums/generatio...und-right.html