[Mark J]

I've got a set of BBC open chamber heads that have a very minimal topcut to the seats, just barely enough of a cut to define the 45* seat. This is how they ended up when dialing in the installed height. Heads have not been flowed but I was curious if the experts here might know if there's flow to be gained on this style head having more of a top cut? And if there's less reversion with the way they are set up now?

This will hurt the flow, you need more width, dont know about the reversion.

 

[Mark J]

Thanks Mark, would a .030 wide 30* top cut be good enough? 2.25" valve

I would shoot for .025-.030. A 30 degree top angle seems to flow more at low lift, and gives up flow at higher lifts, atleast on a GM oval port.