Ter-nan,
Do u have an aftermarket tach? If u do unplug it from the dist, it should be on the left and the B+ should be on the right. I just ran into this at the shop last week. The bosses son had instaled a 350 in an s10 and he had a cute little piece of junk tach. The tach was grounding inturnilly and so there was no sparkles. Try that and let us know.