[RicksGTO]

Could be a lot of things, especially with a new engine. I'd start with the easiest things first and see if it isn't something simple. I'd try and gap the plugs to around .045-.048 for HEI, mine runs much better with the narrower gap with my HEI. Be sure your spark plug wires are all in the right order, look at the firing order again. Check for a vacuum leaks around the carb. base and manifold as well. 16 degrees is a lot of advance, I'd back it down to 10-12 and see how it responds. Try the carb. settings and set your air/fuel mixture with a vacuum guage attached, set it at the mixture that gives you maximum vacuum and see if that helps. Those are a few simple things that you can try in a few minutes for free, so I'd try those first. Also, was the carb. a known good running unit prior to this engine? How were the valves adjusted on this motor as they may be out of adjustment? Good luck on it, Rick.