I am going to be needing some uprated Valve springs once I start building my head up. Now before anybody starts saying LR/KMR/JME et al. I am only looking for the actual spring ratings as Piper Cams are just down the road and I can get Titanium Springs and retainers if I know what rating is required.
Anybody out there know definatively?

Cheers
Tom

 

bump, sorry but need this info!

 

subscribed.

this is relevant for me as well.

 

Don't know myself, but I did get a set from EBS racing and was told they were approximately 30% stiffer than stock. The point is give them a call or send Don Weaver an email and ask him. If he knows exactly he will probably tell you.

I think I remember him mentioning the spring rates to me but it was too long ago for me to remember, should have written it down.

Let us know when you find out.

 

Tom, I have measured the factory springs, and I do have a set of aftermarket ones. If you can hold off till next week, I will not get hold of my notes till Monday.

 

I am not sure that I understand your question. You want to know the rate of a new factory pair? At what 1" or full lift of the stock cam? Are you changing cams? If not are you now using a stock cam? Why are you using Ti for springs and retainers? What are you going to do with the car? What rpm range is it primarily going to run in?

I have a spring tester and have tested a bunch of springs. New OE, used OE, aftermarket you name it.

Sorry but the answer is not for one question.

 

Give Piper Cams your Cam to measure along with all of the Valve Train weights. They will know what to measure. Based upon your RPM requirements and the weights of your Valve Train parts the correct Spring forces can be calculated. The Spring wire stress levels can also be calculated if they know their Springs and what they are made of. They will be able to help you measure the Retainer heights and calcualte the correct installed heights etc with concern about the Coil bind distances. Asking here what you should have is a waste of time.

 

I was about to say that.

The manufacturer will be able to determine the proper spring rates with their design software if you provide the components. You are actually better off having them make it custom rather than using someone else's "cover everything" spring design.

 

Thanks John, that will give us a decent starting point

 

Are you suggesting the spring rating is variable accoding to comprssion? I didn't realise that valve springs were designed to be progressive.
We used to use a spring Dyno to match when building race engines, especially on V12 Jags where there was a lot of stress on the rear cam carriers
Piper have said that we can use software to get a result that would make a good base point however like anything when racing theories, do not always stand up in practice. The car is going to be set up for short track European racing. As we all know the stock valve springs lose resistance after a few thousand miles so there is no point even using them as a base
I was hoping somebody may of had some data.

Cheers
Tom

 

Well, again, what kind of data are you looking for? The factory springs are not very good as you stated. The rate of the spring does in fact change considerablely.

For example, a stock 951 spring at the factory installed height puts approx. 80 or so lbs. of seat pressure on the valve. Without giving away too much, I like to see the seat pressures highter for an engine that is built for racing.

I have never used any software to due this process and for all I know it may be better than what I am doing. All I can tell you is there is a science to it and it is not something I learned overnight. There is a much larger issue to valve drivetrain stability than what we are talking about but that is for another day.

If you want any other info PM me please.