Indy RHS head failure

B3RE said

Easy now, I didn't say they were stronger, I said they had more colleting effect on the valve stem. They won't unlock as quickly as a 10 degree lock will. They can pull through the retainer with high spring loads and valve float, but strength wise, the 10 degree has a heavier wall, which makes it stronger, all else being the same.

Click to expand...

I get it, but the pull through issue is not a big a deal as most make it. To me, the collet effect is much more important.

That said, I usually use 10* stuff because it is more popular and easier to get. I have used 7* stuff with 350 plus on the seat and almost 1000 OTN and the 7's didn't fail.

So, I think like you. The OP has a geometry issue that is causing a harmonic or some other issue that caused the failure.

BTW...if this is the car I have seen it is a dang nice car, and I don't think the OP skimped anywhere. Just a little off on geometry has come back to bite him. You can tell from the posts in this thread that many have much to learn about shaft rocker geometry, if they would admit they don't know or understand.