[Shotimes] Modded SHOs & useless powerbands

[bjshov8]

I can see both sides of this argument.

You want high revs, and you want to open the valves as much as you can.  To
make all of this work you have to have valve springs that are stiff enough
to move the valves and other valve train hardware closed fast enough.  It is
easier to accomplish with direct acting systems because the valvetrain mass
is lower.  On the other hand, traditional pushrod engines mastered this long
ago, even with long duration, very high lift cams used by the racers AND all
of that extra valve train mass.  Well I say mastered it but that is probably
overstating the reliability issue.  With all of that mass moving around real
fast, parts do want to break occasionally.

But wait, I'm going to get to my point here in a minute:
Most v8's that I'm familiar with use rocker arms with something like a 1.6
magnification, so with a .3" lobe you get .48" valve lift.  With a direct
acting system like the SHO, there is no rocker arm, so no magnification, so
with a .3" lobe you get .3" valve lift.  With a 4-valve engine like the 3.0
V6 or 3.4 V8, they probably work without needing a lot of valve lift, but
what about larger engines such as the 4.6?  I know lots of people racing big
v8's are running .6" to .7" lift.  I don't know if it is practical to get
that much valve lift without something in the valve train to add some
multiplication.


> From what I have been reading lately (Nissan KA24 and SR20, DOHC
> 4-bangers) bucket and shim seems to be a much better way to go.  It
> makes the valve train so much lighter than compared to rockers when
> dealing with OHC.  I know with the SR20 they have a big problem with the
> rockers coming apart with revs not much higher than stock.  The KA24
> uses the shims and doesn't have this problem.  If you want high revs and
> usable power, buckets and shims seem to be the way to go.