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> Heads Info, Found some, have dual valve springs?
bd1308
post Nov 20 2006, 11:36 AM
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I found some heads that I think I may purchase, they have dual springs though. Nice stainless valves, but doesnt dual springs put alot of pressure on those valves?
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URY914
post Nov 20 2006, 11:43 AM
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Well it sorta depends on the spring rates doesn't it?
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Brando
post Nov 20 2006, 11:45 AM
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Usually your cam profile determines if you need dual springs or not...

That begs the question -- what else has been done to these heads? And why no pics? (IMG:style_emoticons/default/biggrin.gif)
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Joe Ricard
post Nov 20 2006, 01:37 PM
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You will never rev your motor high enough to warrant dual valve springs.
SO you are just pissing your money away and actually making more internal drag on your motor.
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Aaron Cox
post Nov 20 2006, 06:50 PM
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the weight of your valvetrain (lifters, pushrods, rocker arms, valve adjusters and lastly valves) along with cam profile determine spring rate...along with desired RPM range....

heavier components and pyscho cam profiles need bigger springs to keep stuff from floating
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bd1308
post Nov 20 2006, 06:58 PM
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they look blue in the combustion chamber.

Whatever that means.

If i got them, could I just swap springs out with new other ones?
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brant
post Nov 20 2006, 07:00 PM
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QUOTE(Joe Ricard @ Nov 20 2006, 12:37 PM) *

You will never rev your motor high enough to warrant dual valve springs.
SO you are just pissing your money away and actually making more internal drag on your motor.



this is not quite accurate.
its not all about rpm.. more about cam profile combined with rpm.
my old 2.0/4 had and needed dual valve springs, yet I usually shifted at:
6250-to -6500rpm

brant
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Aaron Cox
post Nov 20 2006, 07:01 PM
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brant, what cam? and what kinda spring pressure?
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brant
post Nov 20 2006, 07:05 PM
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QUOTE(Aaron Cox @ Nov 20 2006, 06:01 PM) *

brant, what cam? and what kinda spring pressure?


I don't think my builder would want me to divulge the cam specs...
and I actually don't know what the spring pressure was.

I can tell you that the heads included titanium spring retainers with about 8 hand drilled windage holes in each retainer...

stainless thin stemmed valves of 38/48 diameter.

brant
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bd1308
post Nov 20 2006, 11:21 PM
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Guys, Trust me.

I dont NEED dual springs. that wasnt my point. I wanted to know if I could change them back to OE spec.
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brant
post Nov 20 2006, 11:26 PM
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most likely unless the head was machined to accept them.

I agree though that if someone put dual springs on those heads you should look carefully to see what else they did. Porting is really an art form that can ruin the streetability of a set of heads when "practiced" by an amateur.

brant
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bd1308
post Nov 20 2006, 11:35 PM
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The heads are blue


Attached image(s)
Attached Image Attached Image Attached Image
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SGB
post Nov 20 2006, 11:40 PM
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They look pretty Krazee (give 'em a glowstick, everyone loves glowsticks)!
Actually why not try 'em at least. Dual springs might allow you to rev a little higher. Where the magnafluxed- or is that possible with AL alloy heads? They look preety kleen! Really, someone thought it was better.... Are the valves stock?
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bd1308
post Nov 20 2006, 11:48 PM
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Well see thats the thing. They were advertised as 2.0 914 heads, but they do not have sodium valves, which means theyre stainless?
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Brando
post Nov 21 2006, 12:10 AM
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Looks like stainless exhaust valves to me.

Makes you wonder why they didn't install stainless intake valves as well though.
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bd1308
post Nov 21 2006, 12:36 AM
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Thats what I was wondering too.
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messix
post Nov 21 2006, 12:43 AM
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dual valve springs were used to avoid spring harmonics, so insane high spring rates wouldn't have to be used.

new tech springs are better and engineered for harmonic suppression. [beehive valves are an example]
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Mueller
post Nov 21 2006, 01:04 AM
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QUOTE(Brando @ Nov 20 2006, 10:10 PM) *

Looks like stainless exhaust valves to me.

Makes you wonder why they didn't install stainless intake valves as well though.



Brando,

I'd guess they re-ground the intakes and replaced the exhaust with SS due to either cost ($15 each instead of $80+ each for sodium filled) or that some shops will not touch/re-grind sodium filled valves. Adding new intake valves would have driven up the cost and maybe they had spent too much already....
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sportlicherFahrer
post Nov 21 2006, 03:24 AM
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Any other pics of those heads? To me they look like 1.7 or 1.8 heads. The spark plug hole angles look off for a 2.0. Looks like they are more upright.
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Brando
post Nov 21 2006, 02:07 PM
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QUOTE(Mueller @ Nov 20 2006, 11:04 PM) *
Brando,

I'd guess they re-ground the intakes and replaced the exhaust with SS due to either cost ($15 each instead of $80+ each for sodium filled) or that some shops will not touch/re-grind sodium filled valves. Adding new intake valves would have driven up the cost and maybe they had spent too much already....


I dunno, it doesn't make sense to me to spend that money for installing dual springs, new guides for the exhaust valves, new exhaust valves and not spend the extra $50-$75 to do the intakes?
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