I'm looking into a set of Manley race flo valves for my 427ci street/strip setup. I have read some pretty negative reviews on undercut valves (breaking) compared to regular 11/32 valves. However, I have really not seen any consistency in the reasons they break. Does anyone here know a whole lot about these valves? I understand that undercuts will give a bit more power, but it sounds like it wouldn't be worth it to me. Any input is very much appreciated.

 

I'm running Manley street flows. (undercut) No issues in two years with double springs.

Mec