I had to drill small holes in throttle plates for engine to get enough
air when starting. The newest Holley carbs have a bypass valve
that accomplishes the same thing.
Make sure engine well grounded with big cable/strap.
What is initial timing?
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.
1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"