Well, the reason behind multiple valve springs is two fold. First, as stated, is the increased spring rate to shut the valves better at high revs. Second, the multiple springs reduce oscillation somehow. At least that was what I was told.
As for why three, truth be told, I had a head sitting on the shelf with the triples and decided I wanted yet another thing to be smug about. "Oh, you only have DUAL valve springs? How cute!" Seriously, I have no other reason.
Oh, and by the way, 6000 RPM means 50 times per second opening and closing.
(6000RPM divided by 60 seconds per minute devided by 2, since we're talking four stroke engines.) Which is still pretty honkin' fast.

My double valve springs are brand new items!
Yours triples are tied ones off an old head you had on the shelf! lol! ( beat that! lol )

I did say the ( engine ) turns over 600 times a second!
I may be dumb ( quite possible ) I forgot to put the 3 before 6000! ( serious! lol! )
but i should have said 100!
But you are right with 50 times a second for each valve!

Looks good! I couldn't help but notice however that one your rocker arms isn't fully "centered" on the valve, and is contacting on a weaker part of the rocker arm. This could cause problems since you're using such a much more heavy duty valve spring. Most A-series have this problem, my dad used bronze washers from the hardware store that fit just right around the rocker shaft, and ground it down to shim it out so the rocker arm was directly centered over the valve. Just a little tip I wanted to share. Another thing is with that much more pressure on the rocker assembly from the springs, as well as the high revs you'll be running I'm sure....anyway I've heard from the guy at Malvern Racing that the rocker arm shaft will tend to "float" from the rocker arm bolts not holding it down to the head very good. He recommended using studs there, and he might have had some kind of trick hold down assembly I don't know, call Malvern, if you want to know more he was pretty helpful with me. What cam are you gonna use in the turbo A-12? What kind of rpms are you looking for? I would love to hear an A series scream to 10,000 like I've heard they can. Good luck!

-Andy

Well obviously three springs are better than two springs -- it's one more spring!

We forget that Dimlight has the ARP stud catalog ... surely the rocker shaft is now held down by studs instead of the original bolts.

Woah! Thanks for the tip Andy! I had noticed that it was slightly off in the picture but hadn't given it much thought. I'll take a closer look at them all and shim as needed.
I also hadn't given the rocker assembly stud idea any thought until now. I'm going to look into that.
As for cam, I'm going stock. I'd heard that was the thing to do with turbo engines.
RPM? When it runs out of power, I'll shift! Seriously, no clue at this time.

It's been a while since the last post, but here's my "guess."

All springs all have a "harmonic" & at a certain number of openings per second the harmonic wave will end up working agains the spring, & it will not be able to do it's job. This means that the valve may not close at all, & i presume it will make passionate love with the piston.
When that happens, the engine's ummmm,.. no longer virginal.

A second spring, with a diferent harmonic rate will not only give some more seat pressure [if required] but will continue to pull the valve shut, even if the other one goes slack on the job.

As for three? I guess that it must be for an engine thats just coming on the cam at about 10,000 rpm. Would that be right dimlight65?
Hey,.. I'm impressed

P.S.
Johnno's garage says, Don't bother with all that dismantling & fitting shims business, just warm the rocker arm with a gas torch, & using a cresent wrench, just bend it to suit.
Squirt some oil on it while still hot to re-temper the metal & she'll be right.

Dodgeman.

Something that I discussed with a mechanic about 3 months ago that build a A15 engine for his brother-in-law to dragrace with.
I asked him if they used double valve springs and he said no they used a single valve spring. He did tell me it was a different car manufacturer's valve spring. I think BMW.
I am not sure.
He said they revved to 8500rpm and it made power up to 8000rpm.
Why does it work?
Is it because the valve spring is very hard to press down and basically has the same pressure as double valve springs?
Something else.
If one puts in such valve springs that are difficult to press, will it not put stress on the rocker arms and cause premature wear?

Using single valve springs seems to work just fine, as long as the harmonic dies not intefere with valve operation within the intended operating speeds.

As for strong springs causing stress on the rest of the valve train, you are absolutely right. Springs should be measured for their strength at the designed "installed height" both at rest, & at the full open position. There is a special tester for this purpose & it is desirable that spring pressures be kept high enough to do the job properly, but low enough to minimise the loading on the valve train components.

Firstly I am not a mechanic but the way it has been explained to me is,

When an engine is high in the rev range ( lets say around 6000 rpm) the valves have to be able to close very bloody fast!
Just think 6000 rpm means the engine is turning over 6000 times a minute!
With 60 seconds in a minute this means the engine is turning over 600 times a second!
So the valve springs are working very hard to keep the valves closed when they are suposed to be closed!

Being this said I to wonder why single heavier rate springs arent just installed?

Hopefully this will shed a tiny bit of light on the subject for you!
And also someone else who knows abit more could further explain why?