I didn't say you were a fool gears, I was referring to myself. If I didn't know about small block pieces that could be interchanged there wouldn't have been a reason for me to reply at all as I would look like a fool doing so.
Let me try and explain this in more detail, this is another engine but the concept is still the same.
In 1994 and '95 Chevy released the L99, which was also referred to as the "baby LT1" it was a 265 cubic inch reverse flow cooled V8. It was the
LT1's baby brother.
Now, these engines came with rods that were PM, and measured 5.940 inches long. We take these rods, then find a 880 casting Vortec 350 Block, then get a 1 to 2 rear main seal adapter, then drop in a crank out of a 307
or if we get really lucky a large journal 327 crank. Next we have the block decked .010 and we use 383 Chevy pistons with a 1.425 compression height.
Slap it together and now we have a roller cammed long rod 327 engine with a rod to stroke ratio of 1.82:1.
As said, he is using the shorter 400 rod, yes, but he's also using a 283 piston.
As we know, all small block generation 1 engines used the 5.703 inch rod, except the 400. Chevy used the interchangeability to it's advantage and it was smart to keep the same rod length and just change the compression height of the piston. This kept costs down.
The 283 came with a 3.000 inch stroke crank, so the compression height on the piston is 1.800, the compression distance is measured from the center of the rod pin to the top of the piston.
The 307 as said has a 3.250 inch stroke, and it too used the same 5.703 rod.
The 307 was a merger of the 283 block and the 327 crank. All chevy did was discontinue the 283 in 1967. In 1968 they made the block into a large journal block, kept the bore size the same at 3.875, stuck the 327 crank in with it's longer stroke, then reduced the compression height of the pistons down to 1.675 and that was that. Since he's using the shorter 5.565 400 rods, he can use the higher compression height pistons of the 283 to compensate for the shorter rod. This practice is done as you can't get 307 pistons anymore that aren't "Rebuilder" pistons that have the shorter compression height and if these pistons were used with a 5.7 rod then the block would have to be decked to it's max plus use the thinnest head gasket available to give it some compression and quench action.