Valve spring?

kokkolanpoika · Post by **kokkolanpoika** » Sat Jun 05, 2010 3:38 pm

Hi.

Can someone explain why this would happen?

Engine is RV8 springs are real steel DW060 one coil less than OE.
Valve lift 12,7mm, spring dosen´t go on tube.
Shimmed to 40,4mm realsteel recon 39,3mm? So i think its not a proplem?
Drived about 2600km and revs are max 6000rpm..
Is it faulty when it leaves on factory?

I but new spring in to the head, and now she is running again..

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bigaldart · Post by **bigaldart** » Sat Jun 05, 2010 4:01 pm

Hi,

It could be that being shimmed to a slightly lighter seat pressure allowed the spring to go into surge, this can and will break springs in pretty short order. It is possible but fairly unlikely there was a fault in the spring itself, however any slight dent or nick in the wire will lead to rapid failure. A good idea is to lightly debur the areas at the end of the spring that have been ground by the manufacturer, do this with a very fine oilstone. Where in its length did the spring break?

Alan

bigaldart · Post by **bigaldart** » Sat Jun 05, 2010 4:08 pm

Sorry picture didn't load at first, now I see it.

Alan

kokkolanpoika · Post by **kokkolanpoika** » Sat Jun 05, 2010 4:25 pm

bigaldart wrote:Hi,

It could be that being shimmed to a slightly lighter seat pressure allowed the spring to go into surge, this can and will break springs in pretty short order. It is possible but fairly unlikely there was a fault in the spring itself, however any slight dent or nick in the wire will lead to rapid failure. A good idea is to lightly debur the areas at the end of the spring that have been ground by the manufacturer, do this with a very fine oilstone. Where in its length did the spring break?

Alan

My local machine shop say that it cant be broke if it too "loose" in the seat pressure. Also my couple of friend say same..

So i dont know..

Theoritically your theory is possible..

bigaldart · Post by **bigaldart** » Sat Jun 05, 2010 11:16 pm

Too loose or too tight it can be broken, I had trouble loading the large picture but what I saw suggests a fatigue failure from a stress riser on the inside of the spring. Likely to be a manufacturing fault if that is the case. Hopefully it didn't do any other damage. For your application I would be inclined to use the double springs or a beehive style spring if you can find one to fit. The double springs are very resistant to surge as they ensure two different resonant frequencies. I have always been worried about a single spring in any performance application, the beehive overcomes that with the change in diameter.

Alan