I am working with some of the newer heads that like a total timing of 26° which is by lieu of the spark plug placement so I’m not clueless in this regard.  The testing for the new heads will quantify if current ignition curves are adequate or if a warning statement must be included where ignition timing attributes must be addressed.

Lorena, Texas (South of Waco)

Re: what Ted said. The Trick Flows on the 408" Windsor in my truck like 28-30 degrees. This is a 9.5 to one motor. anything over 30 degrees loses mph in the quarter. But, It'll run just fine on 89 octane on the street. I'd expect John's chambers will be at least that good. We are all used to 50's and 60's style IRON heads that needed 36 to 40 degrees to work right. Some of my Pontiacs liked 42 degrees with 110 octane. Now I realize that this was a sign of a lousy chamber design.

Frank/Rebop

Bristol, In ( by Elkhart) 

Thank you.