The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Official Difference btween the 396 and 402 BB Because you asked.

**leddzepp** · 03-08-2010, 09:10 PM

As told to me by someone who worked for GM (you won't find it in any book or brochure): The 396 blocks had a casting imperfection in the cylinders, so rather than scrap all of them, GM "fixed" the problem by punching them .030 over making it a 402.

03-08-2010, 09:10 PM	#8
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 19,990	Re: Official Difference btween the 396 and 402 BB Because you asked. As told to me by someone who worked for GM (you won't find it in any book or brochure): The 396 blocks had a casting imperfection in the cylinders, so rather than scrap all of them, GM "fixed" the problem by punching them .030 over making it a 402. __________________ 1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man