Alexandre; Thanks for the reply.
Greybeard, the only answer I know would be that the block is now made with different castings to allow for the bigger bore. Not really all that hard to do if you are GM.
As for the term Iron Duke, I've thought it has been used for the Pontiac 151 since it was introduced. Some change it to Iron Puke but it did differentiate it from the Vega engine which was 140 CID with an under square 3.5 Bore and 3.625 Stroke.
Darrell
