What is the closed valve spring pressure on the L88, ZL1, L72 and LS6 motors? We are having a pure stock race next week and they are talking about checking valve spring seat pressures and are talking about allowing up to 180lbs on the seat. My understanding was that they were around 125-130? Did the l88 and ZL's use more than the 435hp and LS6 motors?
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Re: L88 valve spring pressure
Jeff-----
Valve seat pressure at installed height for the L-88/ZL-1 valve spring, GM #3916164, is reported, variously, at 116 pounds or 125 pounds.
Valve seat pressure for the 1969 L-71 and 1971 LS-6 using spring assembly GM #3970627 is 105 pounds.In Appreciation of John Hinckley -
Re: L88 valve spring pressure
Joe I'm sure you are correct but that sounds low. My son and I race a SBC and we run 375 on the seat. But we shift at 86 and go through the lites at 9. That's with tit valves. One would think that a BB with those heavy valves would need a little more spring pressure in the closed position.
ThadComment
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Re: L88 valve spring pressure
Chevrolet Big Block V8 Quick Valves Quick Reference ChartPart Number Description Outside Diameter Pressure at Installed Hgt. Solid Hgt Pounds per inch Retainer Part Number Notes 3970627 Dual 1.487" 105" @ 1.88" 1.28" 450 3964264 Used with high-performance 396/427/454 production engines; LS-6 3916164 Dual w/damper 1.487" 116# @ 1.88" 1.10" 317 3879613 Used with heavy-duty 427/454 engines; L-88, ZL-1, LS-7. 3989354Dual w/damper1.538"128# @ 1.90"1.26"3303989353Used with camshaft P/N 3994094.140970021.487"110# @ 1.88"--14096274Used with 454 and 502 HO Engines.12462970Dual spring1.514"140# @ 1.940"1.20"36812366990Used with 502/502 engines.Back to TopComment
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Re: L88 valve spring pressure
The numbers that Joe posted for the L88 spring are the same as what I have in some old GM paperwork.
Valve closed.........outer 75@1.88" Inner 41 @1.22"
Valve open...........Outer 193@1.32" Inner 101 @1.22"
375 on the seat is WAY lotsa spring pressure!Comment
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