A 350 engine typically has a standard bore size of 4.000 inches. When it is "bored 30 over," it means the bore has been increased by 0.030 inches. Therefore, the bore size of a 350 bored 30 over is 4.030 inches.
4.040". The standard bore is 4.00".
Displacement of "350 bored 30 over" seems to refer to an engine specification, likely indicating a 350 cubic inch engine with a bore size of 30 over (30 thousandths of an inch larger than the standard bore). This means the engine's cylinders have been bored out to accommodate larger pistons, increasing the engine's displacement. The exact displacement can be calculated based on the new bore size and the stroke of the engine. However, additional information, such as the stroke length, is needed for a precise calculation.
Chevy 350 engines are bored to a 4 inch bore.
a Chevy 350 bored .060 over would be 360.4 cubic inches
4.030"
Most builders feel it shouldn't be bored over 4.065".
Its a 355 cubic inch
A 350 starts out with a 4.000" bore and a 3.48" crankshaft stroke which really only gives you 349.8 cubic inches. (Chevy rounded it up to 350) Your engine which has the same stroke of 3.48 but now is bored .030" over (making the cylinder bored size now 4.030) total size of 355.1 cubic inches or just a 355.
355
Take off a cylinder head and measure the diameter of the bore.
Typically if the motor has been bored the top of the replacement pistons will have it stamped on top of them. for example if bored 0.30 over this will be on the top of the pistons.
It will be close to 315 ci.keep in mind that a 350 is not really 350 but 349.xx or look at this way, for every 030 over in bore = 5 ci.