We looking for a supply of decent quality Inlet and exhaust valves as we are generally disappointed by the quality of commercially available valves we keep buying.
I realised that I don't have a definitive list of which valve sizes and which engines use Sodium Filled Valves and which don't.
Someone on this board is bound to have the information that may save hours of work
Could someone publish a list please.
What brand of valve are you buying that you are not happy with? What problems are you finding?
Rodger@orbitracing.com
TRW Valves are not very parallel and Intervalve seem to have a variable surface finish.
Hello Chris,
you could also consider valves from SM Motorteile...
Chris probably already knows this but I found it interesting.
"With a conventional solid stem exhaust valve, 75 percent of the cooling takes place across the valve seat and 25 percent through the stem. In a sodium-filled exhaust valve, 40 percent of the cooling is through the stem so the valve can tolerate more heat."
Ferrea did some valves for me a few year ago. They were pretty basic though. I think they can make about anything you want though.
Richard Newton
What I am trying to do is to catalogue the range of valves and look at all the differing lengths and come to a conclusion about the weight of the valves.
I am not too sure that sodium is too important in terms of cooling but I am interested to see which engines use this technique to tray to reach a conclusion.
The length difference across the range of valves is also interesting as the standard springs don't seem to change (Other than the single 911T Springs)
If I have understood this correctly the different length will affect the load at fitted length and hence the spring force at maximum lift.
I am assuming that the keeper grooves are referenced to the end of the stem rather than the head.
I am interested to look at the variation in spring force to valve length to try to understand the reasons for the differences.
If we could standardise the length it would help in terms of cost and in terms of keeper design.
Finding the length variation is straightforward but the Sodium filling is more difficult to understand.
I'm not exactly sure what information you are looking for, but as you probably know, the 300 SL used sodium filled exhaust valves with a head diameter of 42 mm and a stem diameter of 12 mm. Experimentation continues with Monel valves regarding their superior heat transfer ability to allow the use of thinner stems.
You might want to take a look at Titanium valves if weight is a concern.
There has been a lot of improvement in valve springs over the past few years.
Until the late 1970s valve springs were made of hard-drawn wire of high carbon steel having a tensile strength of about 1,700 MPa. Then oil-tempered wires of 1,900 MPa grade began to be used. Nowadays, oil-tempered wires of 2,100~2,200 MPa grade are commonly used.
Steve Bown and Larry Luchi recognized that most high rpm engine failures are associated with inclusions within the steel used for the valve springs. Other companies knew this but they never instituted the appropriate manufacturing procedures. Bown and Luchi simply took the time and set new quality control standards for the manufacturing of valve springs.
The standard for valve springs has been Japanese Kobe steel but there has been a real revolution in materials recently. VIMVARVAR (vacuum induction melted twice vacuum arc re-melted) valve spring steel produced in Pennsylvania is currently an alternative to the Kobe steel that’s produced in Japan.
Another development over th past few years has been the pushrod. It doesn't apply to Porsches but if you're working with pushrods engines some of the new stuff is pretty amazing.
Most of our advances have been do to the Spintron. If you can find one in your area it worth using.
The big problem with the valve train is that the goals of light weight and stability work against each other.
Richard Newton
Valve Train Stability
Didn't Smoky Yunick first come up with the 'Spintron" ??
Early S Registry member #90
R Gruppe member #138
Fort Worth Tx.
Guys,
I am just trying to find out which Porsche 911 valves were Sodium filled and which were solid.
I would be interested in any detailed information about Monel Engine Valves as I don't quite understand why this material would be considered as a sensible choice.
Monel alloys can generally only be hardened by cold-working and this would suggest that to make stems that are wear resistant and provide good keeper groove strengths a two-piece construction would be needed.
Titanium Valves are generally not permitted by the FIA in Historic Race Engines and the idea of having to change seats and guides to a Copper-Beryllium alloy is tricky as some machine shops won't use this material.
I realise that there are alternatives but I am not sure how well they are proven.
As a Metallurgist with a background in Engineering Materials behaviour I appreciate the advances made with modern VAR technology and the benefits of cleanliness that have been provided by these techniques.
I would think that in the current environment the best option would be to develop Beehive Springs using an Ovoid wire.
Having spent much of my working life manufacturing both Fatigue and Component Testing the Spintron is interesting but not really a practical method of testing an individual valve spring design.
It is much more appropriate to use Resonance machines which have heated chambers.
These machines have much lower running costs than more conventional AC/DC Motor or Hydraulically powered machines.
This type of machine allows for the testing of the large number of springs to determine the correct statistical analysis to be carried out to arrive at a decent Weibull B10 life.
Many specialist valve spring manufacturers have very limited test capability and have developed simple mathematical tools that attempt to model failure probability without testing and this generally leads to the supply of springs that are 'over rated' for their duty.
The modern VAR materials are then used as an 'insurance policy' to provide increased reliability.
Testing individual springs to characterise them is a subtly different issue and needs a much more sophisticated approach but individual fatigue test results are fairly meaningless due to the stochastic nature of the process.
The smartest machine we made was used to 100% inspect production valve springs, It used a load cell array to initially scrag the spring and then check rate and load at fitted length. The 5 load cells could also plot the load line axis of the spring and ensure it was within the relevant design limits.
I used to make cam test rigs as well as spring testing machines, pump test rigs, single cylinder engine dynos used in F1 and a number of really tricky gearbox test rigs.
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