Thanks for the links Dwight. I did take some calculus and physics courses 40 years ago. I must have learned enough to get accepted into flight school and finish my career as a Naval Aviator. But I never considered myself TPS material. Those guys were pretty sharp (future astronauts). The MIT course sounds fun. But to be honest, I'm probably closer to dementia than going back to school. But I do like Cliff Notes!

 

LMFAO, hands down the funniest thing that I've read all day!

 

Thanks for the links Dwight. I did take some calculus and physics courses 40 years ago. I must have learned enough to get accepted into flight school and finish my career as a Naval Aviator. But I never considered myself TPS material. Those guys were pretty sharp (future astronauts). The MIT course sounds fun. But to be honest, I'm probably closer to dementia than going back to school. But I do like Cliff Notes!
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Please watch how you quote. I never said that. It was INDYMAC.

You wouldn't want someone fasley attributing a quote to you like:

 

As usual Spitfire - there are points agree here and points I don't.

Firstly - I think the most common form of retainer crack is in fact the rapid and uncontrolled slamming shut of a valve (that is not controlled by a cam lobe). That's easy. This type of crack forms over time after multiple insults of lower-level over-revs.
Hence - why I am such a fan of desmodromic valves (Ducati).

I still think there is significant room for discussion for the momentum related 'hammer' effect in extreme over-revs. There are a number of reasons for this that you have spent a better part of several years trying to debunk - yet there is a significant body of experienced and educated contributors that still agree the cam-hammer effect is likely a cause of rapid crack generation in AP1 intake retainers during a higher magnitude over-rev. The key is the same - momentum overcomes cam profile programming due to weak valve springs - and the result is not good - ever.
Hence - again, why I am such a fan of desmodromic valves (Ducati).

 

I don't think he was drinking Heineken - it was likely Stella.

 

Sorry about the comment earlier about the English spitfire, I had apologized earlier as well.

But what are AP1 retainers subjected to that AP2's aren't to cause them to crack?

 

Why would he be drinking Belgian beer?

Surely if not Heineken or Grolsch perhaps Amstel

 

My findings differ...maybe there are characteristics or factors that cause differnt scenarios.

Here is my finding..not on the web, but my own in house test conducted with a local marine racing engine builder of 45 years experience:

When spinning a camshaft at 5500 rpms (the crankshaft speed it takes to split retainers, plus a few hundred) and using other controls...

We were able to reproduce splitting retainers. The noise it makes sounds like a large electric transformer buzzing. I jumped because I though the light above us shorted out

At this RPM, we were able to place a .030 plastic stint between the valve and the head at 5350rpm ...The valve did not cut the stint, it didnt leave a blemish.

The valve did not close. It was opened again by the cam before it would close all the way.

 

It could also be possible that on overrev the valve is vibrating open and closed?