Lotus Elan

Lotus Twin Cam Alternative Valve Springs

PostPost by: SJ Lambert » Wed May 02, 2012 10:58 am

rgh0 wrote:Does your mate have any details on the Isky spring he thinks matchs the Tony Ingram one ?

I had a look at the Isky spring list and none is identical. The nearest i can see is the VWE-006 and the 3405 both of which could be used but both slightly different from the TI spring.

cheers
Rohan


Sorry Rohan. I don't have the details.

Isky refer to their springs as silicon chrome don't they? Are all the good springs a "silicone chrome" make up?
Ford Escort Mk1 Lotus Twin Cam
Elfin Monocoque (Twin Cam)
Elfin Type 300 (Holbay S65 - 120E) mechanic

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PostPost by: rgh0 » Thu May 03, 2012 5:58 am

Hi Steve
There are a variety of spring steel alloys available for making valve springs out of. Silicon / chrome alloys are a modern alloy that has good strength and fatigue characterisitics that a lot of spring makes have adopted. You will see in the Isky catalogue that a couple of other steel types are listed for some of the Isky springs.

Finding references to the actual detailed material specification used is hard as the spring makers tend to keep this a trade secret. But research with the spring wire suppliers should throw some light on the subject when i have time.

My analysis now is focused on the springs physical characteristic and the stresses in it and i am assuming the steel used is suitable with a yield above 240000 psi. Once I have my head around this i will explore materials further.

cheers
Rohan
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PostPost by: qedmotorsport » Thu May 03, 2012 10:06 am

Both our Race and Hard Race springs are made for us by Isky.
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PostPost by: rgh0 » Thu May 03, 2012 12:46 pm

qedmotorsport wrote:Both our Race and Hard Race springs are made for us by Isky.


Hi QED
Thanks for the information - do you know the material Isky use to make them ?.

I not aware you made "race springs" and "hard race springs" what is the difference between the 2 types.

cheers
Rohan
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PostPost by: qedmotorsport » Fri May 04, 2012 8:04 am

rgh0 wrote:
qedmotorsport wrote:Both our Race and Hard Race springs are made for us by Isky.


Hi QED
Thanks for the information - do you know the material Isky use to make them ?.

I not aware you made "race springs" and "hard race springs" what is the difference between the 2 types.

cheers
Rohan


Hi Rohan,

Yes, we do std, blueprinted, Q55, race and race hard. The hard race spring has more poundage then the std race spring but as we no longer build engines and we spec'd these springs many many moons ago, details of their specs aren't really something we have anymore. They were spec'd to be used with our cams so...
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PostPost by: rgh0 » Mon May 21, 2012 1:43 pm

finished fitting the TRR exhaust and getting car ready for racing at winton next weekend so got back to measuring some valve springs again.

Attached is the spreadsheet with height versus load details for all the spring sets I have using a chart similalr to the way Isky show their springs. I will add some more details around the retainers and comments around the relative merits for all the springs when I have a chance.

cheers
Rohan
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spring load ranges.xls
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