400sb vs 400bb - Team Camaro Tech
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post #1 of 36 (permalink) Old Nov 27th, 01, 09:04 AM Thread Starter
DL
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David
 
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Every now & then on this site, I see people people talking about a 400sb. I have a few questions about that:

- What's the difference between a 400 sb and a 400 bb? Is the 400sb more aggressive (higher rpm etc.)?????
- Do you get the same results when both engines have i.e. 450hp. (if you skip the weight aspect)
- How do you make a 400sb (bore/stroke etc.)
- Is a 400sb not "dangerous" because of the metal between the cylinders is getting very thin?
Thanks

David
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post #2 of 36 (permalink) Old Nov 27th, 01, 09:21 AM
 
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I am sure you will get several more knowledgeable replies to your question but I do know a bit about the 400SB because I am building one.

Chevy made the 400SB in two segments. One in the early 70's and a second in the later 70's (don't know exact dates). The earlier ones have a 4 bolt main and the later ones have a 2 bolt main. The 400SB is different from a 305 or 350 SB.
I do know that you can take the crank out of a 400SB and put it in a 350 and get a 383SB.

I have been told that the water jackets on the two bolt 400SB are thicker that the 4 bolt blocks and a stronger 400SB motor would be to converted a 2 bolt 400SB block to a 4 bolt.

You can probably bore out a 396BB to get 400CI out of it but this is where my knowledge falls short.
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post #3 of 36 (permalink) Old Nov 27th, 01, 09:32 AM Thread Starter
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David
 
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jrager, can you see the difference between a 400sb in your car and a 327sb in another car if you only look at it from the outside??
I mean if there are 2 engines, can you tell which the 400sb is and which the 327 when you only look at the engine?

This because the local authoroties can make a problem when I swap a sb with a bb. So a 400 sb is a very nice solution for me

Thanks

David
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post #4 of 36 (permalink) Old Nov 27th, 01, 10:03 AM
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I think are are asking about comparing a small block to a big block as far as performance goes if the two have similar displacement. Am I right?

Well, I read an article awhile back about comparing equally sized small blocks and big blocks. I believe that both motors were built by Sonny Leonard actually. They had a big cube small block and an equally sized big block. Anyway, they determined that the small block was always at a disadvantage due to cylinder head design. Big block heads just flow more air than small block heads.

A 400 small block uses a 4.125'' bore and a 3.75'' stroke crank. A 400 block uses siamesed cylinder walls, which means that there is less substance between the cylinders, but many people run them with no problems. You could also build up a 400 cubic inch small block using a 350 type block if you wanted. Use a bigger crank, around 3.875'' stroke and a 4.060'' bore.
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post #5 of 36 (permalink) Old Nov 27th, 01, 10:10 AM
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the 400 was changed in 75 (i belive) the earlier ones arent as good as the later ones. dont ask me why, i think it has something to do with the cooling system, passages are bigger or something like that. as for looking like a 327, yes the 400 will look like it in just about every way, there may be a few little diffs though, but nothing the average person could notice. the 400 sb wont make the juice of the 402 bb due to head design, as stated. however the 400sb would perhaps be cheaper to build, and might do a bit better on the gas.
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post #6 of 36 (permalink) Old Nov 27th, 01, 10:50 AM
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DL If your talking chevy there is no 400BB, also 400sb had 3 freese out plugs on the side of block other sb engines had 2.

[This message has been edited by Mr. C (edited 11-27-2001).]
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post #7 of 36 (permalink) Old Nov 27th, 01, 10:56 AM
 
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Cool

An interesting side note-As I understand it,back in the 70's when these engines were new,you could order a 400ci engine in a full size Chevy with either a 2bbl or 4bbl carb.
If you ordered the 2bbl,the engine was a small block but if you ordered the 4bbl,the engine was a big block!
I have a 400sb short block that I literally found on the side of the road!! Some day it will make it into the car!

------------------
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post #8 of 36 (permalink) Old Nov 27th, 01, 11:03 AM
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Dave
 
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I don't think a carburator change makes a SB a BB
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post #9 of 36 (permalink) Old Nov 27th, 01, 02:04 PM
 
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Physically, the 400 sbc looks the same as a 305 or 350 when in the car. You really cannot tell the difference. Only when you pop a head off (or pull some numbers) can you see that it is indeed a 400, because as stated above, the cylinders are siamesed, which means that there is no water jacket. The water jacket is replaced with 1/8 inch steam holes.

The 400 BB you refer to is likely a Pontiac 400 block, which is similar in physical size to a BBC. It will not drop right in to a small block bay without some mods, and it is also a fair bit heavier than a true 400 sbc.

Either of these engines is designed primarily for torque, with the long stroke. They are great acceleration engines, and the 400 sbc was originally used in heavy duty towing and RV use. If you want to compare power between the 400 sbc and the 400 "big block", it all equates to roughly the same after the extra weight of the BB and mods is taken into consideration.

The 400 small block chev is the lightest of all GM small blocks by a small margin, and it is not hard or expensive to pull nice mid400 HP numbers, and astronomical torque figures with these engines.
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post #10 of 36 (permalink) Old Nov 28th, 01, 06:13 AM Thread Starter
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David
 
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Thanks again,

Mr.C, I know that Chevy has no 400BB, they are 396BB, and pontiac i.e. has a 400. But I wanted to know if there are large differences between the sb and the BB. I thought there was a very good reason why the +-400ci was always a BB (90 deg).
So the 400 number was only an example. (if there would be 250bb I could ask the same question between a 250sb and a 250bb)
But thanks on the freese out plugs, I didn't know that

I don't know if the 400sb i've seen (here on the site) are Pontiacs or Chevy's or even F*rd's, I thought it would be a great engine for me because of the laws here in the Netherlands. I think the technical inspection guys here could make a serious problem when they see there is a BB in the car in stead of a SB.
The main purpose of the car (in the future when I have the car) would be acceleration and cruising, so I would need tons of torque...... and if I may believe you guys, this is possible with this engine..

Thanks again

David
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post #11 of 36 (permalink) Old Nov 28th, 01, 07:01 AM
 
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Indeed you can. In your case, where you are worried that acting authorities or insurance inspectors would see the larger engine, go with the 400 sbc to replace some other small block. Don't bother telling anyone it is a 400, they won't know the difference without ripping it apart anyway... unless of course you stamp the hood with a c.i.d. sticker, lol.
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post #12 of 36 (permalink) Old Nov 28th, 01, 07:47 AM
 
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Quick question,

I thought a 383 was a 350 block with a 400sb crank and that a 377 was a 400 block with a 350 crank?

Just wondering.

Eric
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post #13 of 36 (permalink) Old Nov 28th, 01, 08:50 AM
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I thought I've read somewhere before that the "396" offered in the early 70's was really punched out to "402" but the fender badging still said 396-then they started badging that motor as a "400" a couple years later and that is where the sh!t hits the fan because of the development of the 400sb. I know I read about this somewhere, just can't remember the source.



------------------
Bret Copsey
'68 Camaro base coupe
'92 Caprice wagon
'98 Malibu
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post #14 of 36 (permalink) Old Nov 28th, 01, 08:54 AM Thread Starter
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David
 
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Do I have to build my own a 400sb, i.e. take a 350sb bore it and stroke it until I get a 400? Or can I buy a early 70's or later 70's factory built 400sb like jrager and badcam wrote before and will this fit a '67/'68 camaro?

Breathweapon, I have no intention to put a 400cid sticker on the hood....maybe a 230cid sticker LOL

David
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post #15 of 36 (permalink) Old Nov 28th, 01, 09:10 AM
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it wouldnt be advised to bore a 350out more than about .030, the older blocks (early 70s) can be bored out .040 or .060 i dont remember. either way you will have overheating problems. if you want 400 cubes the best way would probabally be to get a 400 engine. if you cant get a 400 build a 383. but like i said you shouldnt bore a 350 out that much. at least and put many miles on it. if you want a 383 try larriys' performance (323-722-8865) they offer 383 kits that dont cost an arm and a leg. i dont know whether or nor these guys are any good, as i have never bought from them. you might want to check their reputation. i hope this helps. feel free to e-mail me if you have more questions.
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