I have a 454 with a torquer manifold , the problem was that the motor had no bottom end and popped through the carb. I replaced the stock advance shims and springs witha mr. g set , tried the middle set of springs . It was better but still popping a little I tried the lightest spring's today . The motor has come to life now , no popping and pulls very strong .The initial timing is 10 degrees advance it seems to like it there best. I've tried more but 10 is the smoothest. If anyone has this similar problem , I thought I would share this info with everyone.