Thread: school me on valvesprings

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Originally Posted by Bouncer

From what your link provided I would choose VSK-0001

Be sure to add ZINC additive to the oil if you want to keep the lobes on the cam.

thanks for the info, as far as the zinc ill be running a racing oil that includes the zinc additive

This is an interesting exercise for those of you who like to play with numbers (like me ) .

0.2600" intake lift at the cam will theoretically be 0.390" intake lift at the valve and 0.2733" exhaust lift at the cam will theoretically be 0.410" exhaust lift at the valve with a conventional 1.5 rocker arm. I say theoretically because I don't think there ever was a true 1.5 stamped steel rocker produced by Chevrolet. Every one I ever checked was less than that, with some down around 1.45:1 as I remember. That's one of the reasons to purchase aftermarket rockers, because you get the true design lift at the valve. At any rate, we'll consider that this young man has some 1.5 rockers and that the valve lift is 0.390"/0.410".

Pro-Tek didn't supply us with the spring RATE, but we can figure it out.
Coil springs are pretty much linear as you apply pressure to them, so if the VSK-0001 springs are 103 on the seat and 300 lbs @ 0.500" lift, a difference of 197 lbs, then we can divide 197 by 500 and find that for each 0.001" of lift, the pressure increases by 0.394 lbs.

Now, if we multiply 390 times .394, we find that the pressure will increase on the intake by 153.66 lbs from valve closed to valve open at full lift. Now, if we add the seat pressure to that (153.66 + 103), we find that the intake spring pressure is 256.66 lbs. over the nose. Multiplying 410 times .394 will tell us that the exhaust pressure increase is 161.54 lbs. Adding 161.54 and 103 will tell us that the exhaust spring pressure over the nose is 264.54 lbs. We can drop the decimals and just call it 256/264.

Now, since we know that pressed-in rocker arm studs begin to pull out of the heads at pressures around 250 lbs and higher, we now know that we must either pin the studs or pull the studs, tap the holes and install screw-in studs or we can mill the pads, tap the holes and install screw-in studs with guide plates.
http://www.summitracing.com/parts/MRG-806G/