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

*67/72junkie* · 05-20-2010, 01:11 PM

only differance in 396 and 402 is 030 overbore. Same casting # blocks cranks ,heads,same cam and piston comp in same hp rated engines. 402 would make an estimated 6 hp more than 396 with same parts due to 6 more ci but GM kept the ratings the same.Why call what every one knows as 325 hp 396 a 331 hp 402 lot of trouble and confusion for nothing when everyone knew what SS396 was. You can take late 1969 casting dated 325 hp 396 bore 030 deck the block to remove stamped production code and install in early 1970 402 application and no one would every know the differance if you didn't tell them. most engines have date codes of mid year previous to build.

05-20-2010, 01:11 PM	#67
67/72junkie Account Suspended Join Date: Oct 2002 Location: NC Posts: 1,129	Re: Official Difference btween the 396 and 402 BB Because you asked. only differance in 396 and 402 is 030 overbore. Same casting # blocks cranks ,heads,same cam and piston comp in same hp rated engines. 402 would make an estimated 6 hp more than 396 with same parts due to 6 more ci but GM kept the ratings the same.Why call what every one knows as 325 hp 396 a 331 hp 402 lot of trouble and confusion for nothing when everyone knew what SS396 was. You can take late 1969 casting dated 325 hp 396 bore 030 deck the block to remove stamped production code and install in early 1970 402 application and no one would every know the differance if you didn't tell them. most engines have date codes of mid year previous to build.