Precision Oil Pumps rockers

[Pentroof]

I have been running these rockers for a few years and absolutely love them. A friend just told me that he is changing his because he broke a couple due to high spring pressures. Nothing serious like a solid roller, something like 400# at lift. He said that Doug changed his design to beef them up at some point but I was not aware of this. Is there any supporting experience out there.

[jayb]

Doug has told me that his rockers are not suitable for solid roller applications with high spring pressures, but I'm surprised that they would fail at 400# open.  I am not aware of any redesign that has been done on Doug's rockers.  Your friend doesn't have any pictures of the failed rockers, does he?  How long was he running them.

FWIW, aluminum fatigues over time, and after a certain number of cycles at a high stress level an aluminum rocker is going to fail.  Your friend may have just reached the limit on a couple of them.  On Drag Week in 2007 Jack Miller had a couple of T&D aluminum rockers fail, and those rockers are supposed to be the best available.  A steel rocker is a lot better in terms of fatigue resistance and long life.

Seems to me that Bill Conley on this board may have done some FEA analysis for Doug on his rockers a while back, maybe he will chime in on this - Jay

[Pentroof]

I'll get some photos. I was not aware of a change either, that's why I posted.

[WConley]

Hi guys -

Nope, I didn't do an FEA study of these rockers.  I'd be curious to have a look at them though.  Did they break under the fulcrum or out towards the arm?

I'm just resurfacing after a trip to Europe (and then a flog to catch up on my work!)

- Bill