The con rod length alone will not necessarily change the stroke depending on the pin location in the pistons. Stroking means to use a crankshaft which has a longer throw. The SBC 350 has a throw of 3.48" while the SBC 400 has a 3.75" throw. In the past 400 cranks were adapted to 350 blocks but today there are a number of places to just buy a 3.75" throw crankshaft new. After the throw is changed care must be taken to match up the new crank with the proper rod length and pin location in the pistons to keep the piston near the deck height of the block at top dead center. Stroking the engine increases the swept volume of the engine displacement and usually improves the low end torque but may reduce the top rpm. I don't know much about 327s but I think the stroke was 3.25" so the 327s tended to rev higher while the 400s have a lot more grunt but a lower rpm limit. An interesting additional factor is that if the pin hole is raised and longer rods are used the tendency to detonation (ping) is reduced but often the same 5.7" length rods are used with a 3.75" stroke; this leads to a slight bit more of side slap of the pistons in the bore and also does not help reduce detonation, so 6.0" rods are better with a 3.75" stroke if you can buy the longer rods. I am a novice with the SBC having only helped build my own 350 but I recall when the Ford flathead V8 had a standard stroke of 3.75" and had good low end torque which became montrous when a 4" stroke crank from a '49-53" Mercury was swapped in, so I have great respect for the effect of stroking. In the case of a SBC 350 swapping in a 3.75" crank requires some clearencing at the bottom of the cylinder bores to clear the longer crank throw. I could not afford to pay for this and did not want to chance grinding the block myself so I just settled for a 0.030 overbore rebuild for a 355.

Don Shillady
Retired Scientist/teen rodder