I doubt the CR is @ 11.0:1 here,not unless the short block was zero decked and the heads had been shaved some before being shaved that .012" this time.
The common pistons for these 400 engines sit down in the hole like .020" on average,so that typically puts the CR closer to 10.0:1 when used with most any of the common small chamber big valve heads like those 670's.
Most of those small chamber big valve heads will be over 72cc when "virgin",typically they are closer to 75cc or so,so that .012" mill just puts them 2cc or so closer to the "nominal" 72cc spec that we all know so well.
Besides,there can be a lot of explainations for those sorta symptoms,many of them are related to common tuning chores,others are often related to minor problems like vacuum leaks or such.
I can see a few things I'd change in this combo,but most of what's going on with this is likely things that are only loosely related to those items I would wanna change.
In the right hands,I bet this could be "whipped into shape" in no time.
2¢ FWIW
Bret P.
__________________
This space for rent... 
In the meantime,check out the cars HERE.
|