Billman250

We found out about the part number change a day or two ago, but didn't have the numbers themselves....Good work bro

yogi

Now if we can drag 'ol Woodwork in here to explain (if he knows) the difference between the old part and the new one...

xviper

I'll PM him a link of this thread and see if he responds.

Slows2k

I'd like to know what he says as well.

xviper

Woodwork sent me this pic with the following explanation:
"The valve end is still in the split retainer. Too much force on to close
the valve without the rocker pushing on the other end of the valve."

apex2k

Did anything abnormal show up on the compression test??

Woodwork

Thanks for posting the photo xviper.

I think I have posted this before but here goes again:

I have data to show that the S2000 engine will live at redline. The problem is that any more than 9,000 RPM will allow the valves to "float". This means that the cam is turning so fast that the rockers can't stay in contact with the cam lob. As this happens the rocker doesn't push on the valve stem constantly. If the rockers are floating then the valve spring is going to slam the valve closed as hard as it can since the contour of the cam lobe isn't gently closing the valve. (9,000 crank revs per minute is 150 per second/2 or 75 valve slamming per second). With the valve spring at full force closing the valve the only thing stopping the valve is the valve seat but the spring is still working (pushing the retainer up) and the only thing stopping the retainer is the keeper and the valve. Thus the retainer starts to split when the valve isn't controlled by the cam.

When the engine goes more than 10,700 RPM the valves stay open long enough to get slapped by the piston. That is when you see the valve bend and then break off. If the valve only is bent a little it may bend back each time the valve spring is pulling on it and it may close properly and not cause a misfire code. Eventually it will fail and cause extensive damage. That is why someone can say "I was driving slow down a city street and it just failed". That is usually a true statement.

HTH,

woodwork

yogi

and there we have it!

S2KenC

Thanks for the explanation woodwork. Always an informative post from an invaluable member on this site.

Billman250

Good points have been made here. Questions that still remain are:

-Are the 04 retainers stronger, and dimensionally compatible to consider an upgrade...

-Only one out of 16 valve retainers failed, one other APPEARS to have started to fail. Why just this one...

WOODWORK....Major thanks for your contributions here. What do you think of this as a cure for future models....A simple electromechanical device incorporated in to the slave cylinder, controlled by the ecu...It could disengage the clutch at, lets say, 100-200 rpm's higher than the engines preset rev limiter, thus preventing mechanical over-revs.


Just a little info on Woodwork's pic...What were looking at is the underside of the retainer. The gaps at 9, 12, and 3 o'clock are cracks in the retainer. The next gap in the inner ring appears to be a damaged keeper.