Originally Posted by 40forddgc
I just put a new 350 cubic inch in my 40 Ford. It runs really well. It has a new 575 dual feed Holey. At low idle it has 5 vacuum and under load it has 15 vacuum. My question is why is it dying at low idle?
The needle of the gage is steady, but low at idle? It might just be a question of where you are sampling the vacuum at. If it's from a ported vacuum source, it could behave the way you describe.
Otherwise, check for the initial timing being low, vacuum leaks, etc.
An undamped gage is better for diagnosing engines with- it allows the needle to move at the least provocation.