how to get 340 into 12,s

matty, i think you have enough motor to into the 12's easy. like the others said the mph is there and that tells you the motor is making the hp. also like was said get timing set first. next adjust the pump cam arm, open the throttle all the way up with motor off and see if a .016" feeler gauge fits between the cam and arm. if it does you're good to go, if not adjust it. next with the motor in park or neutral and running. take your hand and open the trottle as fast as you can. there should be instant throtte responce without any hesitation. if there is you need to add squirter size until it's crisp. now hit the track. idling in first stab the throttle it should respond cleanly without bogging. if it bogs add more squirter until you're happy. all this is because you have an intake with a large plenum and a 1" spacer on top of it. that's a lot af air that is moving rather slow at idle and it will need alot a gas shot into it to richen it up to get the hotrod to move quickly. try and find a holley book on tuning and you will read about alot of neat things about tuning a carb.