All things being equal what would be the better engine for a mild street cruiser does one engine have a advantage especially when it comes to torque on the street

If they were 100% the same...and in the same exact car, i would say the 400 would have the power advantage due to more cubes.
Ed

i always would opt for the 400, but i can see why some people would rather have the 383, because of block reliability being better. also there just aren't as many 400 cores out there anymore, while the 350 isn't as commonplace as it used to be, there are still plenty of them out there right now.

What advantage could a motor with a given stroke but a smaller bore have, over a motor with the same stroke but a larger bore?

Of course the 400 is the better motor; it's more inches, and it's just a bolt-together since it's already there, no clearancing or special parts or anything. Assemble and enjoy.

The problem with "More cubes" is that the 400 block can be more fragile than the 350 block. There's also hugely more 350 cores to select from than 400 cores.

Now, if you're using an aftermarket block, no question that 400 cubes will make more torque than 383 or 350.

Depending on the heads, you might run out of breath at a lower RPM, though.

My choice? I built a 400.

I've personally have seen many 350's fail, but that's probably just because there are more out there compared to 400's.

You can't go wrong with a 400, IMO. If that's not enough, go BBC.

The 400. Plain and simple... it has a bigger bore. Although the 400 blocks are weak in some areas. Ive been told to look for the 509 block if you want a factory one.

given all the same parts and since it is a mild motor Under 5000 rpm??
I would guss the same power even though the 400 will breath better due to the valve unshroulding due to the bigger bore.

Definately go with the 400. I had a 383 in my Chevelle before I got the 400 and the 400 has more power and torque. Here is a link to my car page with engine pics on page 2.
http://members.cardomain.com/zachschevelle

What about a 406? I'm curious because I linked to an article from the Probe / Coast High Performance website. A magazine bought one of their 406 shortblocks and put cast iron GM heads on it. I almost fell out of my chair.

..."at 2,300 rpm, the engine was already making 471 lb-ft of torque."

"It made 525 lb-ft of torque and 428 hp all under 5,500 rpm."

Best power with 91-Octane, 35 deg total timing, 1 5/8 headers and a 750cfm Holley. What are the pro's and con's of the 406? I want one! What would happen if you put in one of UDHarrold's Voodoo cams (say the 268)and better heads? I mean, these guys went low buck (under $6000 total) Would there be enough gain to justify spending more on a better set of aftermarket heads? For arguments sake, my personal preferance is for a high-torque small-block street engine. Guys?...

Wouldn't, technically, if you're looking for a more torquey, flat power curve, you'd want the 383?

How would, technically, a 383 have a more torquey, flat power curve than a 406?

Yeah, and how would only an aftermarket 400 block make more than a 383. Common sense says all else being equal, the 400 will ALWAYS make more power.

There are plenty of 400 blocks out there. You have to know where to look. Then have them sonic checked for about 50bucks and your ready to go.

The only reason people have problems with 400's is they mismatch the heads and block for the steam hole option. The 400 had more meat in it too.

I second the notion for a 400. The 406 is just a .030 over 400, so it has basically all the same pros and cons of a 400. The only difference could be extra heat if you started with a real thin wall casting and then bored it .030 over. The siamese bores sometimes crack. The best 400 you could get is a good cast two bolt cause they are stronger than the 4 bolt blocks. If you really need it to stand up, fill it partiailly with some hard blok(dont fill it all the way, just a little to bulk it up). Next, do all your standard machining and go ahead and drill the bottom end for splayed 4 bolt mains and use good caps and good bolts/studs to put everything in there together. Thats a little overkill for your average street motor, but if your that concerned about it, you can go for it and you will have one tough block.

Either engine can be built to run good, but due to the extra cubes, its easier to build the bigger one to make the power you want at a lower rpm. Thats why if you have the option, the 400 is the way to go for what it sounds like you want. Just remember to steam drill whatever heads you get for the 400, and put together a descent cooling system and you wont have any problems with overheating if you keep a good tuneup too. The 400 has a bad rap for overheating, but I dunno why cause they seem to do just fine if you take the proper precautions that you would with any larger, more powerful engine.

i had a 406 in my daily driver...loved it! go for it! easy to build!

Originally posted by onovakind67:
How would, technically, a 383 have a more torquey, flat power curve than a 406? Because it has a longer stroke, doesn't it? And doesn't that make for a more torquey power curve, or at least for low end? I know they are different blocks but just as far as stroke is concerened.

Originally posted by MustangKiller:
I mean, these guys went low buck (under $6000 total)$6K low buck? LOL..low buck is the $2500 454 in my car or the other low buck extreme,the used,turnkey 455 Olds I bought for $400 that ran high 12's :D

..I guess low buck is a relative term-no offense smile.gif


While 383 stroker kits are cheap,and 350 cores are plentiful,I'd rather have 400 small block myself.

hey ouchevelless
the 383 is a 350 block with a 400 crank
if I'm not mistaken the stroke would have to be the same on a 383 and a 400

Ah okay, that would make sense. I knew how the 383 was made but wasn't sure what the stroke of a 400 was. Thanks for correcting me

400 without a doubt.

400 small blocks use a 3.75" stroke

400, Period. Go for the cubes.

just remember to run either 5.7 or 6" rods for best power advantage! i wouldn't bother with the factory 400 rods..they are shorter.

If you go 400 definitely go with a 2bolt main and start your build from there. I opted for the 383 build...I just didn't have the patience to search for a nice 400 block, drill and tap a hole for the clutch bar, etc...JMO.

My dad had a 400 from his 80 3/4 ton that I'm using. The bores were way out so I had to go .40 over. So 408 or 409. I hope to not have any issues with it. I went with Eagle H beam 5.7 rods and had to clearance the block some. I thought about a 383 as we had 350 cores to but I wanted the extra cubic inches. Same costs, I think pistons were a little more. But I should be getting 500 hp and 500 lb/fts out of it under 6500 rpm.

Go 400 if you can find a good core.

406 any 2 bolt will be fine, my 406 13/1 pro topline heads in a 3300 lbs cutlass ran 10.80 on motor and three years strong. no over heating i just got an aluminum radiator and plug the bypass in the water pump and i only run the moroso waterpump drive kit and i have trouble getting heat to the motor

I'm having difficulty even understanding why the question was asked to begin with.
It's almost like asking whether to go with a 305 or 350.

Probably because they are almost close.

Speaking of this, I'd like to ask about the 4 bolt main 400 blocks...I've heard the 2 bolts are better but I'd like to ask if the 400 4 bolts are any good in terms of high performance?

I ask because I know where there is a '77 Chevy 1/2 ton with a 400 in it....they want 3k for the truck...I'm guessing it's more than likely a 4 bolt main...could always buy it and swap the 400 for an old tired 350...resell it for 2800. :D

Years ago (80's) you couldn't give away a 400 around here, for some reason they had a bad reputation for overheating and cracking. I think it was probably the heads that were failing first but I've seen quite a few blocks that have cracked between the steam holes and head bolt holes. I've assembled a few engines with cracks already there and they lived just fine- go figure? graemlins/clonk.gif

my 383 is bored to .60 over which makes it about a 388.. does that 12 extra cubes really make THAT much of a difference?

Just curious smile.gif

yes every bit helps

Had a bad experience with a 400 block. A crack in the cylinder wall was overlooked by my builder. If I ever go another 400 block I will make sure I know the history of the engine... just to play it safe. All in all it really comes down to the engine builder himself. Make sure all crack testing is thoroughly done, and I mean thoroughly!

Why not go big and install this (http://www.sdpc2000.com/catalog/335/products/46899/383ci-SB-Chevrolet-4340-Steel-Crankshaft.htm) crank from GMPP. It's the crank GM uses to build it's 383 motors w/o boring the block. It's forged and has a 3.80" stroke, rather than using a 3.75" and a .030" over 350. Pop this sucker in a .030 over 400 block (you'll need bearing spacers, commonly used to de-stroke 400's turning them into high revving 377's) and have a nice torquey 412 sbc.

Just a thought.

If I could start all over again, I would just go with a 400 instead of the 385 stroker, if not just to save some cash. All the clearancing, balancing, and machine work added up to a pretty penny. Had I gone with the 400, the money I spent on the above mentioned machine work could have gone towards a nice set of heads or other go-fast parts. graemlins/thumbsup.gif