backyardmechanic
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Ok I replaced a nonfunctioning distributor with a new dist. with electronic ignition on the 74 MGB. It has a new weber downdraft with new manifold that was installed by the owner. The car has a backfire through the carb when accelerating. It idles ok but a little rough still. I have gone through the carb tuning process which did not seem to improve the situation much. From all the information that I have read the backfire is a sign of too lean of a mix. I have backed out the mixture a significant amount to get it to run as well as I can. I think this might also be a sign that the jets are too lean although when I pull the plugs they are a black powdery looking which would indicate a rich mix. This stumps me? I also have the timing sharks teeth on the upper side of the crank cover unlike the two books that I have that show these to be on the underside.There are five sharks teeth indicators. By watching the #1 cyl. I have determined the TDC to be the top tooth in the array. Am I to assume each of these teeth represents 5 deg. of timing? If so, the only way that I can get the car to run well is setting the timing to about 15-20 deg. BTDC at idle. With the new dist. I have plenty of advance now and it advances to well Before TDC now. Is my timing a problem as well? Thanks for any help/insight you might provide. Backyard Mech.