[Tim Corcoran]

Back in the day there weren't much available for Pontiac after market rods so Jim Butler, and probably others figured out if you turn the Pontiac rod journal down to 2.2 you could use a BBC rod, but they didn't come with 6.625 length and a 6.8 BBC rod was available. With the .040 smaller size rod journal now you could offset grind the 455 crank and get a 4.25 stroke 455 and make a 473 with a .060 over 455. Then you needed a custom made piston to move the pin location. I actually learned this by talking with Jim Butler back in 1995. So originally it wasn't to get a better rod to stroke ratio but it worked out that way. This made the 4.25 stroke cranks popular and they started selling cast 4.25 stroke 455 cranks with a 2.2 rod journal and a 4.24 stroke and it has evolved from there.