TFS A-460 head question

Riddle me this,.......


While I was disassembling my new 18-bolt, TFS A-460 heads today (so I could get them ready for a little pocket porting and a very mild clean up), I noticed something that struck me as very odd. Why did Trick Flow decide to install spring cups & shims ONLY on the intake valves with a smaller ID than the OD on the valve seals?

Now,....
The exhaust valve seals have a smaller OD,......so the cups & shims can be easily removed.

I can't remove the cups & shims on the intake side w/o first removing the valve stem seals.


I don't think it's really a big deal to leave them in place while I do the porting,.......... it's just a little more difficult to keep machining debris out of the area and makes clean up a little harder & more time consuming.

Specs are as follows,......

intake valve stem seal OD - .670
exhaust valve stem seal OD - .630

Cups & Shims ID (hole size) - .640


Does anyone have any idea why these are set up like this?

It is usual to have to remove the seals to remove the spring cups. P51/FRPP SCJ/TFS A460 and others.