Got an L78 (396/375) that I can't seem to get dialed in. From what I know its a spec numbers matching numbers type rebuild with very low miles on it. When i got my hands on it, it had like 24* degrees initial timing and a big vacuum leak under the carb. The vacuum advance was hooked up to manifold vacuum. Got the vacuum leak fixed, put the right gasket under the carb. verified TDC #1. Set initial timing at 4* BTDC and it just does not like it. I can't keep the throttle plates closed under about 18* initial timing. and even then the motor is producing bupkiss for vacuum at idle. I've been banging my head against this thing for a couple of days and its time to step away for a minute and collect my thoughts, and see if you guys can think of anything I'm missing. Any Ideas? Thanks in advance.