Dave, I found similar with Dynomation 5. I've e-mailed Larry about that, and the fact the shape of the curve didn't match what I've seen. As far as the timing goes, I beleive its just based on the generic head categories. I'll look through the his replies to see if there was anything more informative.

I think Cab is right - its based largely on Chevy motors. It's hard for me to beleive that the crank to rod ratio and the combustion chambers don't effect best timing curve. Shrinker thought it did, and I give him more credence on such things than the simulation program.

Mr. P - that's interesting about the 40* on the dyno. When Hot Rod tested a 340 on Edelbrock's dyno in 1969, they claimed to be using 39*.