429 stock, car warmed up set timing 8 btdc 28 btdc 5 vacum total 41. After long drive vacum back up to 10. Canister is turned out as far as I can get it which is fine until driven. What's up?

 

You have to excuse me because I can't fully understand what you are attempting to tell us.
Not sure what you mean by canister.
What is this engine in?
Where are you taking the vacuum readings ?
What is the idle speed?
How about you clue us in as to just what you did, and want to do with this engine?
Take your time and don't leave out any details. Every piece of info is important.
I'm not good with a crystal ball and I can only go by what you tell us, thanks.