Are you sure you're timing it with no1 cyl on the left hand side of the block,[from the front],dont know firing order of hand,are you sure the condenser is clean and earthed to the distributor,i've had problems with this in the past.Will check firing order if you require?poss your timing is 180 degrees out,try turning the motor over one more turn to get the no1 valves shut on the firing stroke.