Primarily the bore size. The 305 has a bore of 3.74 and the 350 is a 4.0 bore. They share the same stroke on the crank. And no, you can't bore a 305 to a 4.0 bore.
no. the bore and stroke are as follow the 305 3.736''x 3.48" and the 350 4.000"x 3.48"
No. The bore size is different between a 305 and 350. The 350 bore size is larger.
Subtract 305 from 350 and that will give you the difference (or interval) between the two numbers:- the answer is 45. However, if you mean what is the difference between a Chevy 305 and a Chevy 350, then it is the difference between the engine bore (the cylinder) sizes. The 305 bore is 3.740 inches. And the 350 bore is 4.000 inches, giving the Chevy 350 20HP more then the Chevy 305.
4 inches like the 350
no.
No, 350 has a substantially larger bore.
the pistons are the same diameter. no they are not the same diameter, the bore on a 305 is smaller than a 350
No. There isn't enough material in a 305 to bore that far oversize without hitting water.
NO The bore and stroke is different.
No. The 350 has bigger valves. While you CAN put the 305 heads on the 350, (I can't imagine why you would actually want to) you can NOT put the 350 heads on the 305. Because of the 305's small bore, the valves on the 350 heads will hit the cylinder block.
Decode the engine number stamped on the machined flat pad just below the front of the passenger side cylinder head. In addition to the above answer if you have the head off you can measure the bore. A 350 has a bore of 4.0 and a 305 has a bore of 3.74. The stroke is identical on both engines.