Hey guys, i know that this is a stupid question, but I am very curious. I know a 396 is a big block and a 400 is a small block. Obviously the 400 has more cubic inches, but I know most big blocks will make more power (relativly speaking). With the 396 being a big block will it make more power than the 400 that has a few more cubic inches on it because it is a SB?
Thanks for your time guys
Tom

Hey Tom,

The 396 uses a 4.094" bore with a 3.76" stroke. A 400 sb has a 4.125 bore with a 3.75" stroke.

I believe in stock form the bbc makes more power due to a better head design (canted valve vs. wedge design).

I think both engines have their place...it's your decision.

------------------
Todd Geisler
79 Malibu
Malibu Muscle
http://www.MalibuMuscle.cjb.net
Naive...I was.
Skeptical...I am becoming.
Determined...I have always been.
"The only way to fail is to stop trying."

so which engine would it be easier to make say 450 HP with. So if i am seeing it right the 396 being a big block doesn't give it any advantage?

Todds right. Its all in the heads. Look at the new small block with evenly spaced runners and different combustion chamber design. (modernized big block in small block disguise) Over 1 hp per cu in and it still passes emmissions and has a smooth idle and a full warranty. The LS06 Corvette is 385 hp from 327 cu in. Idle is smooth pulls like snot. Heads and intakes and cam timing/profile.

[This message has been edited by d1_bradley (edited 02-07-2001).]

[This message has been edited by d1_bradley (edited 02-07-2001).]

Well said Todd!

------------------
TheSlicksty7 (http://home.mindspring.com/~mbridges420/_uimages/chevelle.jpg)

Was my response "politically correct" enough? http://www.chevelles.com/forum/biggrin.gif

------------------
Todd Geisler
79 Malibu
Malibu Muscle
http://www.MalibuMuscle.cjb.net
Naive...I was.
Skeptical...I am becoming.
Determined...I have always been.
"The only way to fail is to stop trying."

I think Todd's answer was very well written, and I wasn't even offended by it! I don't want to pick nits, but aren't the vettes 5.7 liter motors, which works out to be about 347 cu in? Still impressive no matter how you slice it.. http://www.chevelles.com/forum/smile.gif

347? A 5.7 is a 350

Actually the new LS1 series engines (LS6 included) are 346 cubic inches but still called 5.7 liters(there close). The previous 350 cu in engines are even closer to 5.7. The also have a 5.3 liter (327 or so) making 270 hp and its in a truck!

I would say the heads is the biggest improvement. The ports can be equal to the LS6 style head(rectangle ports) on a 396 and when compared to small blocks' ports, even the good flowing stock heads...there is no comparison. For instance port volume small block may be 180 cc and big block is way over 200 cc(I don't have access to my reference-sorry).

Also consider the stock highest gross power rating for small chevy was 375 and the big chevy was 450 for 396.

It is interesting question I have thought about as well seeing as I have a couple of 400 small blocks. Hope that helps.

JSL, the difference comes when you start converting CID to LD. The metric system gets bulky when you start listing the actual CID/L ratio as something like 5.6 and change. A "Chevy 350" in in reality a 347 which is why a +30 bore gives you a 355. Never question the archane terms, just accept.

------------------
Francis Taracido Gold# 201
sniper0666@aol.com
History shows again and again how nature points out the folly of man.
Oh No! You Know She's Got To Go!
Go Go Quadzilla! <oo=+=oo>
http://members.aol.com/sniper0666/page/intro.html

As long as you're talking about it.....what exactly is the 402 I hear about? Is it a bored 396? Did Chevy make a 402BB for production, or is it an aftermarket engine?

Although I do agree with Todd, if I were given a budget and a choice, I would do the 400sbc......less weight and roughly the same power. Most 400sbc guys will end up going faster than 396 guys

A 402 is the equivalent to a 396 bored out .30 I believe (could be .20 or something i dunno).

Yes they were a production engine. There are all sorts of stories as to why but i don't think anybody knows for sure.

IMHO if your going with a big block dump the 396 and go with a 427 or 454. Why use a 396 BB when you could use a 400 sb and have a weight advantage? I'm not dumping on guys with 396's or anything, but if your looking to build an engine I think it would be foolish to go out looking for a 396 block unless your going for originality.


------------------
Chris Dagenais
Saskatchewan
'71 Malibu with a home built 454!
"Hard work MAY pay of in the long run, but laziness pays off NOW"
My Page (http://www.ycworld.net)

During the switch from 396s to 402s, there were a number of 402 engines supplied in cars but called 396.

I can't remember if the 402 bore is 4.125" or 4.130"? But it is definitely a larger bore 396. I don't know for sure what the deal was with the 402. I heard a rumor that Chevy found a bunch of railroad cars with 396 blocks that had surface rust and bored them to 402 to salvage them.

I heard another rumor concerning emissions and the 396 with closed chamber heads vs. better emmisions with the open chamber heads and for some reason the slight increase in bore size was to provide some emissions benefits over the 396 bore, but personally I can't see how that would be.

But these are just rumors, anyone care to elaborate?