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Author Topic: Hitchcocks competition valve set for EFI  (Read 237 times)

Roeland

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ace.cafe

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Re: Hitchcocks competition valve set for EFI
« Reply #1 on: May 26, 2014, 12:53:25 PM »
Interesting!

You won't be needing them, though.
Your head has the beehive springs.
 8)
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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Roeland

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Re: Hitchcocks competition valve set for EFI
« Reply #2 on: May 26, 2014, 01:09:32 PM »
What would be the a deciding factor between choosing either double springs or beehive springs?

ace.cafe

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Re: Hitchcocks competition valve set for EFI
« Reply #3 on: May 26, 2014, 02:20:08 PM »
What would be the a deciding factor between choosing either double springs or beehive springs?

Once the need for spring pressure gets higher than can be attained with a single spring, then the dual coils are necessary. Usually at very high lifts and very high rpms. For instance, our racing head for Bullet Whisperer in the UK is designed for 8250 rpm and .600" valve lift, and that required almost 500 pounds of spring force over the nose, and needed dual coil springs.
For anything that can be performed by a single spring, the beehive is better for control of unwanted harmonics and surge, run cooler, last longer, and will perform better at lower spring pressures, for less wear.
If there is a choice in the normal rpm range of dual-coil springs vs beehive, beehive is the better choice in every regard, except maybe cost.


Here's a link to a high-speed strobe motion video for a brand of beehive springs, and it shows the dual-coil springs with valve bounce(every time that rocker moves up and down that isn't a full stroke is valve bounce), vs the beehive spring that is in perfect control.
http://www.youtube.com/watch?v=NskusJdk5Qs

Now, of course this doesn't mean that dual-coil springs can't control the valves. They certainly can. But they generally need higher spring pressures to do it, and they often have harmonic problems and spring surge problems because their single diameter coils can be excited into motion by certain frequencies, and the conical beehive shape is inherently essentially immune to that unwanted behavior. And the beehive is much lower weight because of the conical shape, and there's only one spring instead of two. And the springs don't have to rub together to damp harmonics out, because there are no harmonic problems, so the beehive runs cooler from no friction on a second spring.

It's not that dual-coil springs are "bad", it's just that the beehives are better. And that's why we use them when the application permits it.
« Last Edit: May 26, 2014, 02:58:59 PM by ace.cafe »
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

Please visit my new website:
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Roeland

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Re: Hitchcocks competition valve set for EFI
« Reply #4 on: May 26, 2014, 03:22:20 PM »
Thank you - great explanation - I look forward to the completed head.

gashousegorilla

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Re: Hitchcocks competition valve set for EFI
« Reply #5 on: May 26, 2014, 07:34:55 PM »
 A good read...

 http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/retainers.html

  Also, the UCE motor has a nice feature in that it has a valve spring/valve stem cooler.  Oil is sprayed from an orifice from the side of the rocker blocks at the valve spring.
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.