assemetrical bottom cuts?

[talon]

Good morning gents

I am reading some from D. Vizard's book on chevy small block cylinder heads.

In it there is a section regarding High Flow zone "A" and low flow zone "B". Sec. A is the area of the SSR and ex. valve side. Sec B is the remaining. He makes mention of "As the valve lift progresses to the mid and upper ranges, the port speed becomes too high for the air to successfully make the short-side turn and adjacent valve area." To me that would make a reference to having a steeper bottom cut(s)....say 65 instead of 60 - followed by a second 90 cut - again only in this area - Sec. B would still employ a 60 bottom and followed by 75. I assume that the cuts for Sec."A" would be offset from valve centerline so that we could a steeper approach to the valve seat and get the cutting tool to clear.


Fast forward a couple paragraphs. He is talking about the way to machine these areas. To me it is the opposite to what I have described above. He says to cut Sec. A then offset for Sec. B. If we do that and Sec. "A" employs a 65/90 bottom cut(s) - there will be no material to machine when we switch to the 60/75 for Sec. B.


There are many times my head is screwed on backwards...is this one of them?

Thanks for the input
Jim

[SBC]

On page 74 of the book I have, none of the short turn is included in section A (section A was identified as the high flow zone)

[talon]

Hello sir

yeah that's it .... the high flow zone goes from the 10'oclock to about the 4'oclock - from 10 to 2 is the short turn

Jim