21,23,28 degrees timing question

[sphanna]

There was an excellent post by a well respected engine builder a while back that described the max timing for original and HC engines. 21* for 6;1, 23* for 5.5;1 and never above 28* for stock 4.2 head.

I very much would like to find this post. I. printed it so as to have this info but I have misplaced it. Can any one direct me to this post? My search was unsuccessful. Thank you..