Official Difference btween the 396 and 402 BB Because you asked.

[lovnthe70]

I personally think there was a conspiracy between two guys sitting in an office having a little whiskey in their coffee one morning when one of them said to the other " you know what would be funny John" "whats that Bob?" "lets turn this 396 into a 402 and then badge it as a 400……. then when the internet comes out we can sit back and laugh at all the enthusiasts who try to figure it out!!!!! ” “sounds good Bob…. Lets get to work”

[70cst]

Originally Posted by lovnthe70

I personally think there was a conspiracy between two guys sitting in an office having a little whiskey in their coffee one morning when one of them said to the other " you know what would be funny John" "whats that Bob?" "lets turn this 396 into a 402 and then badge it as a 400……. then when the internet comes out we can sit back and laugh at all the enthusiasts who try to figure it out!!!!! ” “sounds good Bob…. Lets get to work”

[Pickupmanx2]

Originally Posted by lovnthe70

I personally think there was a conspiracy between two guys sitting in an office having a little whiskey in their coffee one morning when one of them said to the other " you know what would be funny John" "whats that Bob?" "lets turn this 396 into a 402 and then badge it as a 400……. then when the internet comes out we can sit back and laugh at all the enthusiasts who try to figure it out!!!!! ” “sounds good Bob…. Lets get to work”

See,,,that's EXACTLY what I'm talkin bout!! Good one!!

[leddzepp]

Originally Posted by lovnthe70

I personally think there was a conspiracy between two guys sitting in an office having a little whiskey in their coffee one morning when one of them said to the other " you know what would be funny John" "whats that Bob?" "lets turn this 396 into a 402 and then badge it as a 400……. then when the internet comes out we can sit back and laugh at all the enthusiasts who try to figure it out!!!!! ” “sounds good Bob…. Lets get to work”

With all the different reasons and GM workers with different explanations, this one makes the most sense to me now

[Monte Carlo Man]

Just for the sake of telling you, my Uncle was one of those SCCA Racers that you are talking about. Telling me how the 302 was designed and built would be like telling Colonel Sanders how to make chicken.

When I was a kid, there was a 68 Z/28 in my friends parents front yard that he bought to keep the pine tree sap from hitting the ground.
There was also a 1963 Split Window Coupe Corvette and several other cars in his parents yard that he never drove.

My Uncles last race car was a 70 1/2 Z 28 - Brown with White stripes.
373 posi with a M 22 transmission.
We kept rock salt in a crate from Chevrolet that they sent a set of replacement heads in. They were known to crack.

Also, my uncle was associated with Yenko Chevrolet when he lived in Pittsburgh in the late 60's. He was also very good friends with Don and a woman named Donna Mae Mims who worked for Don Yenko that was a new car salesperson and drag raced under the name - The Pink Lady. You might recognize her from the movie Cannonball Run.

Big block stuff is ok for wreckers and crew cab pick up trucks and heavy hauling, but for real performance you got to stick to the small block stuff.

Here is a really good one for you though.

The 70 1/2 Z 28 came with a 350 that was conservatively rated at 350 HP, it was actually more like 500. The 400 Small Block Chevrolet was rated at 375 HP.... They had 4 bolt mains also and were discontinued in late 72...
With the 400 - you didn't have to worry about the heads cracking - you knew that they were going to crack around the steam holes. The bigger problem was when the crank fell in the pan because the whole bottom end (block) would crack around the webbing for the main caps and the engine would self destruct. I had one that the rod came out through the oil pan and it still ran and when I took one bolt out of the oil pan, the oil filter fell off - engine block and all.

The big block engines were known for throwing the #7 rod or loosing the bearings or the wrist pins in the #7 piston or puking the rings out the exhaust. I had several sets of heads that had .

[Monte Carlo Man]

There also was correspondence out in the garage from that era from Vince Piggins and also from Joe Pike..

Joe Pike was the head of sales and promotions. He was the person responsible for getting those high performance parts out the back door and into the hands of the racing community. Stock car racing - Junior Johnson
Drag Racing - Donna Mae Mims and road racing Don Yenko and Mark Donahue.

http://www.67z28.com/history.htm

Yenko Chevrolet - 575 West Pike St., Canonsburg, PA
Nickey Chevrolet - 4501 Irving Park Road, Chicago, IL.
Dana - Long Beach Blvd. South Gate, CA.
Berger - 2525 28th Street SE, Grand Rapids, MI.
Baldwin Motion - 598 Sunrise Highway Baldwin, Long Island, NY
Fred Gibb - LaHarpe, IL
Those were some of the dealers authorized to sell those cars...

http://www.hotrodscustomstuff.com/camaro-history.html

http://www.firstgencamaro.com/hiperf.html

[70cst]

As I look at these posts it's interesting how many of us have heard as to why the change from 396 to a 402BB took place. These are all interesting reads. Who knows...maybe someday we will get actual GM Documentation to what really happened. Good read all..

[67/72junkie]

show me pics ,mag article,gm lit of any chevy car with 375hp 400sb from the factory and make a beliver out of me.All 400 sb are low comp from the factory.I have blue 1971 GM motors manual and specs for all engines with codes to decode witch paticular model it came in.I have 5 70/72 515 casting 4 bolt main 400s and 4 more later 2 bolt main 400s which are the stronger blocks.I can show you specs for any 1970 gm engine you what right down to the gm specified clearances.Lt1 370 hp 010 casting high nickle 4 bolt main block 11 1/2 comp,forged steel crank,pink rods 186 casting 64cc heads 3/8s screw in studs 2.02 & 1.6valves solid lift cam,aluminum dual plane intake,780 holley.1970 400 sb 515 casting block heads 598 casting ,441 in water port on underside of head 3/8s press in studs 1.94 & 1.6 valves light dishtop 4 eyebrow pistons 9 1/2 comp cast crank small hyd cam most came with 2 barrel carb.This is not from a book but in my head.I have built at least 50 sb 350s and 400s in the last 20 years.I have 13 sets 64cc heads from stock to super stock modified at least 1 set every casting made from 1963/1971 461,461x,462,291,292,040,041,186 show me specs for 375 hp 400 sb factory.Teach me something I don't know about a small block chevy.

[67/72junkie]

only the copos where factory gm built with 427 .all the others where factory SS396 with dealer installed gm crate 427.Out the back door is not factory availible from the assembly line to the public and they had no crate perfomance small block bigger than Lt1 350.Hence Yenko Decuce if you wanted sb super car.

[Walts_restoration]

Originally Posted by 67/72junkie

show me pics ,mag article,gm lit of any chevy car with 375hp 400sb from the factory and make a beliver out of me.All 400 sb are low comp from the factory.I have blue 1971 GM motors manual and specs for all engines with codes to decode witch paticular model it came in.I have 5 70/72 515 casting 4 bolt main 400s and 4 more later 2 bolt main 400s which are the stronger blocks.I can show you specs for any 1970 gm engine you what right down to the gm specified clearances.Lt1 370 hp 010 casting high nickle 4 bolt main block 11 1/2 comp,forged steel crank,pink rods 186 casting 64cc heads 3/8s screw in studs 2.02 & 1.6valves solid lift cam,aluminum dual plane intake,780 holley.1970 400 sb 515 casting block heads 598 casting ,441 in water port on underside of head 3/8s press in studs 1.94 & 1.6 valves light dishtop 4 eyebrow pistons 9 1/2 comp cast crank small hyd cam most came with 2 barrel carb.This is not from a book but in my head.I have built at least 50 sb 350s and 400s in the last 20 years.I have 13 sets 64cc heads from stock to super stock modified at least 1 set every casting made from 1963/1971 461,461x,462,291,292,040,041,186 show me specs for 375 hp 400 sb factory.Teach me something I don't know about a small block chevy.

Ever seen a 64 327 300 horse chevelle? They did make many
Had factory 2.5inch exhaust manifold, all by them selves, exhaust all by them selves.. we have the block and trans out of the car, dad saw the car come in new on the car hauler, and pulled the block from a hedge row out of a circle track car about 15 years back.



Also, didnt 400s, at least some, have the nodular iron crank? isnt that why people had the 400 cranks turned down for a 350 over an aftermarket forged?

[70cst]

Originally Posted by 67/72junkie

show me pics ,mag article,gm lit of any chevy car with 375hp 400sb from the factory and make a beliver out of me.All 400 sb are low comp from the factory.I have blue 1971 GM motors manual and specs for all engines with codes to decode witch paticular model it came in.I have 5 70/72 515 casting 4 bolt main 400s and 4 more later 2 bolt main 400s which are the stronger blocks.I can show you specs for any 1970 gm engine you what right down to the gm specified clearances.Lt1 370 hp 010 casting high nickle 4 bolt main block 11 1/2 comp,forged steel crank,pink rods 186 casting 64cc heads 3/8s screw in studs 2.02 & 1.6valves solid lift cam,aluminum dual plane intake,780 holley.1970 400 sb 515 casting block heads 598 casting ,441 in water port on underside of head 3/8s press in studs 1.94 & 1.6 valves light dishtop 4 eyebrow pistons 9 1/2 comp cast crank small hyd cam most came with 2 barrel carb.This is not from a book but in my head.I have built at least 50 sb 350s and 400s in the last 20 years.I have 13 sets 64cc heads from stock to super stock modified at least 1 set every casting made from 1963/1971 461,461x,462,291,292,040,041,186 show me specs for 375 hp 400 sb factory.Teach me something I don't know about a small block chevy.

Good Info...

Monte Carlo Man ...
I am not sure what your thread has got to do with the 396-402 thread? Lets keep this about the subject at hand and if you want to start a subject about your interest that is great....

['72customdeluxe]

Originally Posted by Monte Carlo Man

The 70 1/2 Z 28 came with a 350 that was conservatively rated at 350 HP, it was actually more like 500. The 400 Small Block Chevrolet was rated at 375 HP.... They had 4 bolt mains also and were discontinued in late 72...
With the 400 - you didn't have to worry about the heads cracking - you knew that they were going to crack around the steam holes. The bigger problem was when the crank fell in the pan because the whole bottom end (block) would crack around the webbing for the main caps and the engine would self destruct. I had one that the rod came out through the oil pan and it still ran and when I took one bolt out of the oil pan, the oil filter fell off - engine block and all.

errm, i'd say 350 gross was about right http://www.superchevy.com/technical/...lley_carb.html
Sure it has compression and plenty of cam, but the heads flow maybe 210 cfm and it's only 350 cubes. Not a recipe for a monster. Through full exhaust, accesories, and stock manifolds it *might* have made 300 at the crank