Why the overbore from 396 to 402

[resto4u]

Gm has done some weird things. They put 400 emblems on trucks that had the BB 402, go figure. [img]/ubbthreads/images/graemlins/dunno.gif[/img]

[copo9566aa]

Another strange move for GM in 70
GM never put the new 400 SB in a Camaro for what ???
emission or warranty problems or bigger problem with this
new block for 1970 ???
GM like more overbore the 396 to 402 [img]/ubbthreads/images/graemlins/dunno.gif[/img]
Strange move [img]/ubbthreads/images/graemlins/biggthumpup.gif[/img]

[COPOL89]

Its funny you mention the truck emblems, My 72 Cheyenne is a 402 with the 400 badges. [img]/ubbthreads/images/graemlins/[/img]

[Pantera]

I will have to check it out later but I have a 72 super Cheyenne that has a 402 emblem on it. [img]/ubbthreads/images/graemlins/dunno.gif[/img]

[JTH74]

I think that Jerry McNeish said in his book that some of the late 69 SS396 Camaros were actually 402's, I will have to go back and read that chapter again just to make sure, I remember him saying that the block casting #'s changed.

[Chevy454]

On the same note, some head changes were made along the way in '69 as well. I found this out by accident, as I bought a set of 840s that had never had valves or seats put in them, but were made for the 1.88 exhuast valve, and tapered plug. On the shelf we had a set of 840s that originally had the 1.72 with flat seat plug...the interesting part is they were cast in the SAME WEEK (in May sometime). So, I had the last of the old style with specs of the new style, just by luck. I called MacNeish and Colvin and they said that was correct, that they did a changeover in May sometime to get ready for the upcoming year, and my 840s were kind of a mix between the old 840s and the new 291s. Some cars ended up with 291 heads on them, and it's probably safe to say some got "funky" 840s like the ones I have.

Some wierd stuff took place back in the day... [img]/ubbthreads/images/graemlins/smirk.gif[/img]

[JoeC]

some late 69 Chevelles have the 402

[55chevy]

I've seen a few Chevelles that way too. Non-SS cars. I've seen a few 71 402 Heavy Chevy Chevelles with 400 air cleaner decals on the 402. And I've seen a 71 Malibu with a 402 BB that had 400 fender emblems and air cleaner decal.
Probably too many Chiefs going on back then. That's probably why there were so many different things going on at the same time. I'm sure everyones been in that situation. [img]/ubbthreads/images/graemlins/headbang.gif[/img]

[camarojoe]

I've heard stories about the 71 Heavy Chevy Chevelles, and that depending on what transmission you ordered along with the 400 engine, you would either get a 402 big block or a 400 small block, and both were called "400" on the order sheet... I don't know if that's fact or fiction, but wouldn't it be a bummer if you and your buddy both ordered 400s and he got a big block and you got a small block? [img]/ubbthreads/images/graemlins/blush.gif[/img] That would be my luck! Anyone ever hear of this? [img]/ubbthreads/images/graemlins/dunno.gif[/img]

[55chevy]

I can't remember ever seeing a 400sb in a Chevelle. Seen plenty of them in Monte's and Full Size but that's not to say a Chevelle never had one. [img]/ubbthreads/images/graemlins/dunno.gif[/img] The 400SB was a fairly mild engine wasn't it?