Stroker crank

If a 350 had a stroker crank installed just the crank what would the displacement be?

Ya can't just change the crank.

What stroker crank, how much additional stroke, you need to research what you are asking here. And yes you would need pistons and rods.

Depending upon deck height and some other clearances a "stroker" crank can be installed. Technically ANY increase could be called a stroker , but commonly it is a large increase that required welding or a crank from another model engine. I agree with above , the key question is "what is your new stroke"?

Regardless of any other disclaimers the displacement answer that you seek is figured the same way as any other displacement (bore and stroke needed) In your case we know the bore of the 350.

The formula is π/4(x²yz) where x is the cylinder bore, y is the stroke and z is the number of cylinders. Put more simply:

Bore X bore X stroke X # cyl X 0.7854

ex.

4 x 4 x 3.48 x 8 x 0.7854 = 349.848 (round up to 350).

For you? 4 x 4 x ? x 8 x 0.7854 = ?

The missing variable is the stroke you want to convert.

As others have said, you will need new pistons and/or rods if you decide to do the 'common' stroke upgrade - the 3.75" stroke of the crank on a 400, which with a .030 overbore will yield 383 cubic inches. The longer the rod you select, the more torque your engine will make - but keep in mind the compression height of the piston (this is the location of the wrist pin in relation to the crown of the piston) will change with the stroke. You *could* run the 5.565" rods of the stock 400s and keep the stock 350 pistons, but this increases piston side loading - which is not conducive to life in a performance application.