Vacuum question!

The demons I've worked with are all race demons. They are finicky with idle mixtures staying steady (the idle hunts between rpms), and they were perpetually rich. They needed air bleed changes. Easy, except nobody stocks Demon air bleeds but places a day or more away. So, now tuning is a week worth of adjust, order, install, adjust, order. I can get holley stuf (and have some) locally. Nevermind the physical issues I found. If you have an LM1, I think it wil drive you crazy tuning. Because you'll get it perfect one day, then the temps will drop 10°, and it will feel all off again. It is cool to see how it all works together tho.

I regard to idle speed and vaccum, that's a heck of a drop for 300 rpm. I would verify the timing curve first. The better heads, I'd be aiming for 18° initial, and around 14° or so centrifical. You shouldnt need much more than 32-33° total in any case. Then proceed to set the carb. You cant do the carb, then timing. Because the timing will change what the engine wants for fuel.