340

I have a 70 340 40 over 9.5 to one pistons j heads with 2.08 intakes 160 ex. ported polished roller rockers port matched air gap intake 780 holly all new . all work done by a great racing engine builder . but it is not running up to par . I pulled and changed the plugs twice and some are lean some are rich never seen this before . I don't know why some would be rich and some lean . ??????