[mclairmo]

You can lose a lot of fuel economy with no vacuum advance but it really depends on your engine combo. However, if the engine won't run at all without the vacuum advance hooked up to full manifold vacuum sounds like you have bigger problems. Maybe your initial timing is set too low, or your mechanical advance mechanism is froze up, which happens sometimes. Or maybe your balancer has slipped and you cannot get an accurate reading? I would confirm that your balancer is accurate at TDC and then use a timing tape to dial in your timing with no vacuum advance hooked up. Then worry about the vacuum advance after you got it running smooth.