I have a 305 sounds like it is dropping a cylinder when I start it up and rev, tried adjusting dist, timing checked cap, rotoe, new wires any suggestions???

 

I would do a compression test on that cylinder. Might have a burned out valve.

 

Fire it up and use a pair of plug wire pullers and pull one wire
at a time off the cap until you find the one that does not drop the
idle or make it miss worse. That is your dead cylinder. Pull the
spark plug out and see if it looks ok. If it looks good swap it with
another plug, put it all back together and fire it back up.
Again pull the plug wires off one at a time and see if the miss
stayed on the same cylinder or moved to the cylinder you swaped
plugs with. If it moved to the other cylinder, the plug is bad.

If the miss did not switch cylinders check the plug wire real good
and swap it with a known good one if you have one. If the plug
wire is good, you need to do a compression test on that cylinder.
If compression is good, swap the injector for that cylinder.

 

checked wires, changed plugs, carbed not FI, engine ran fine in car I took motor out of put into my car and now seems like missed cylinder cap and rotor?? O2 sensor?