engine and drivetrain Valve Guide - Major Failure --Why?

[TobyB]

 

I mapped the cam lobes and lift at 1 deg. increments,

You're a maniac.  5 degrees was mind- numbing enough, although I did increase the resolution around max. lift...

 

t

[oldguy]

You have officially "dropped a valve"

 

Needs more Piston to valve clearance..  

 

ross won't make anything "fast" without a rush order fee.

 

Did you clay all the holes or just one? Because due to differing seat depths during machining, the clearance can be tighter on one than the other.

 

I'm surprised it didn't break the rocker.

[markmac]

Probably completely unrelated, but when my Schnitzer engine was disassembled the fellow who did the tear down also was an engineer that studied oil rig failures and such out in the gulf.....bla, bla, bla, at any rate he put a number of the valves from that motor under the microscope and found that many of them had very (very) tiny cracks in the steel (at the top of the valve and in and around the keeper area).  Told me trying to re-use something like that in a high revving race motor would lead to "unfortunate" circumstances very quickly.  Not sure how many cycles your valves had been through but who knows.  Something to possibly consider.....

 

www.alpinabmw2002.com

[FB73tii]

Kris, I did clay all eight valve pockets. Will post data later. All installed spring heights were identical (within 0.001), so I would  think seat depths the same as well. Yes, the KM Cams steel rocker arms must be strong! I'll have to get it inspected or buy another one as I don't want it to fail down the road.

Mark, thanks for the data point. The valves had about 2.5 hours on them, including cam break-in, dyno runs, and the 20-minute track run.
 

Thanks--Fred