Stock49 - I have read a number of articles on header design but your summary above is the best I have ever read. Great Job.
Warren - I have built 2 different 4 into 1 headers and a dual header set for my 302 GMC. It has the same exhaust layout as your 261. I asked for Inliner help and summarized my experiences on the Inliners Bulletin Board topic:"GMC/Old Chevy Single Headre Design Questions", 11/13/10 - 11/17/10. Another Inliner discussion titled:" How to make an I6 exhaust header" appeared from 7/19/10 - 10/14/10. You might want to use the Bulletin Board's search feature to look these up. Two other good discussions appeared in the Landracing Forum by some famous inline 6 Land Speed Record holders. They are: "321 GMC inline 6 header", appeared from 9/2/07 - 10/11/07 at the following address which still works: http://www.landracing.com/forum/index.php?action=printpage;topic=2878.0 A second one titled: "INLINE SIX EXHAUST HEADER" appeared on 7/6/08 - 7/9/08 at same address but topic number is changed to =4160.0
Hope this old info helps you. Good Luck.
Frank Hainey , radar
