Originally Posted by RWENUTS
When going from a spreadbore intake to a squarebore carb you need an adaptor like eddy #2732 or you get a vacuum leak along the sides.
And try 12*. My stock 230 six banger luved it. Won't hurt anything except your wallet. You'll get better mileage and save some money.
My tweaked 350 sbc I had with aluminum heads, big crane cam, headers etc used 22* initial. It's the crap gas you buy now.
Edelbrock.com - Installation Items - Adapters & Spacers
I have an adapter plate made for the Carter's to adapt it to this manifold, and I don't have a 12 BTDC mark on my engine, I would have to guess at it.