Some 4Ag Valve Spring Specs

As per FSM specifications(AE86 and AE92) 4AG valve springs are to be checked @ 34.7mm(1.366")

1.366" (34.7mm) This is our standard. All spring were brought to this point, and from this point on coil bind was found. On advice from Loynings, .050" off coil bind is maximum "allowable" VALVE lift. I capitalized VALVE lift because it is different from cam lift* in this situation.

From an unknown source -

some valve spring information...

 

http://honda-tech.co...9/#post44221375 - Honda VTEC thread of valve springs - many show specs of .2mm between bind and max lift

 

.2mm is a .008" or a LOT tighter then many accepted specs.....

*Coil bind doesn't change - with heating, valve stem length can "grow", but with the stems "growth", so will the spring, BUT when compressed, the coils will still bind at the same point - thus for purposes of valve springs - valve lifts, and not cam lifts are being referred too.

OEM stock (USED) - 35#s @ 34.7mm(1.366"), full bind comes in @ .349", subtract .050" and you are left with .299" before "effective coil bind". Pressure @ "effective coil bind - 96#s - Spring was bound @ 1.017"

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  Since for this test I didn't have any new OEM springs I used 2 used springs. For point of fact... I recently did have some new OEM springs, and only 14 of the 16 springs actually met the minimum height in the FSM, the other 2 were within .03mm or less - spec is 41.09mm The two used ones I have measured out to 40.92, and 40.90. So they were pretty close.
  

HKS - 30#s @ 34.7mm(1.366"), full bind comes in @ .415", subtract .050" and you are left with .365" before "effective coil bind". Pressure @ "effective coil bind - 120#s - Spring was bound @ .951"

Toda - 42#s @ 34.7mm(1.366"), full bind comes in @ .419", subtract .050" and you are left with .369" before "effective coil bind". Pressure @ "effective coil bind - 128#s - Spring was bound @ .947"

BC 7MG valve spring - 58#s @ 34.7(1.366"), full bind comes in @.486", subtract .050" and you are left with .436" before "effective coil bind". Pressure @ "effective coil bind" 168#s - Spring was bound @ .880"