I'm installing a new electric range in our kitchen and I pulled out the old separate cook-top and oven and was surprised to see only two wires and a ground coming out of the wall for each appliance. My new range is 220, could I just tie all 4 of the old wires together and change out the 30amp bridged breaker and 50amp bridged to one 220? Any help would be great.

Have you checked your main to see if the feed is dual pole breakers for each circuit?
How about the way the wires are connected to the breakers, what color wires?
What is the conditions of the exisitng wires? This might be a good time
To replace them, as well as update to the latest NEC codes.
What is the load requirement of your new oven?

In our house, the existing electrical wiring for our Hotpoint 220v oven/range,
Is a outlet with 3 wire AL, but the ground isn't connected. This is on a dual pole
50A breaker. In fact our central-air wiring is done this way, with the ground
Cutoff at the entrance to the main and not connected. I guess in some years ago,
Electrician that wired our house, did not believe in grounding 220v.

You could cap off the 30 Amp, Can't parallel, then use the 50 for new range, Match receptacle to Plug.
New Construction and remodel should have 4 wire Cord and receptacle. The wire can be # 6 if Copper.

abcsalem, you should connect or have ground connected at both ends, This way if a Hot wire touches case, it will trip breaker, Not Become Live, Silently, Deadly.

I'm installing a new electric range in our kitchen and I pulled out the old separate cook-top and oven and was surprised to see only two wires and a ground coming out of the wall for each appliance. My new range is 220, could I just tie all 4 of the old wires together and change out the 30amp bridged breaker and 50amp bridged to one 220? Any help would be great.From what I'm reading I would say no go! Yet, check to see what size wire you currently have. If it's not a #6 copper or larger, or #4 Alum or larger, then you are out of luck, and would have to run a new branch circuit conductor (#6cu as mentioned above. )