I'm using a Demon carb for the first time. From the box it doesn't come with a butterfly valve. Is this due to design differences between Holley and Demon? Seems weird. Found it difficult to start my newly rebuilt engine unless I maintained greater than 2000 rpm.

Which model Demon are you running ? My 650 Speed Demon has an electric choke and vac secs. It runs great.

650 with mechanical secondaries. It appears that the electric choke is an available add on.

Husker,
I am NOT a carb expert. But without a choke, electric or manual any carb Demon or Holley is going to be a pain to keep running until warmed up.