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* · 05-14-2010, 01:02 PM

starting in 1970 all 396 where changed to 030 from factory to make 402.030 396 piston is same as standard bore 402.This was done due to the fact that small block 400 was introduced in 1970 and gm did not want a sb with more cubic inches than bb.I have friend who collects chevelles. he has 1969 and 1970 SS396. Both have SS396 badges both are 325 hp 1970 is 402 but has same casting # on the block and both have 290 casting closed chamber heads monte carlo man 400 sb introduced in 1970 was hi torque motor and not considered hp at the time 515 casting 4 bolt block with 265 hp. With lt1 186 casting heads and cam it will make more hp and outperform lt1 but not from the factory. lt1 was 360hp in camaro and 370 in corvette

05-14-2010, 01:02 PM	#31
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. starting in 1970 all 396 where changed to 030 from factory to make 402.030 396 piston is same as standard bore 402.This was done due to the fact that small block 400 was introduced in 1970 and gm did not want a sb with more cubic inches than bb.I have friend who collects chevelles. he has 1969 and 1970 SS396. Both have SS396 badges both are 325 hp 1970 is 402 but has same casting # on the block and both have 290 casting closed chamber heads monte carlo man 400 sb introduced in 1970 was hi torque motor and not considered hp at the time 515 casting 4 bolt block with 265 hp. With lt1 186 casting heads and cam it will make more hp and outperform lt1 but not from the factory. lt1 was 360hp in camaro and 370 in corvette Last edited by 67/72junkie; 05-14-2010 at 01:12 PM.