400 sb, 350 sb.
350 = 4.000" x 3.48" (Gen.I, 5.7" rod)
350 = 4.000" x 3.48" ('96-'01, Gen. I, Vortec, 5.7" rod)
350 = 3.900" x 3.66" ('89-'95, "LT5", in "ZR1" Corvette 32-valve DOHC, 5.74" rod)
400 = 4.125" x 3.75" (Gen.I, 5.565" rod)
The 400 is a good platform to use, just typically run a bit more $ than a 350 (but not by too much)
350 = 4.000" x 3.48" ('96-'01, Gen. I, Vortec, 5.7" rod)
350 = 3.900" x 3.66" ('89-'95, "LT5", in "ZR1" Corvette 32-valve DOHC, 5.74" rod)
400 = 4.125" x 3.75" (Gen.I, 5.565" rod)
The 400 is a good platform to use, just typically run a bit more $ than a 350 (but not by too much)
Staging Lane
Joined: Nov 2004
Posts: 72
Likes: 0
Build you a nice little 406 , they make great street/strip engines. also just looking at the blocks , a 400 sometimes has 3 freeze plugs on the side which is a dead giveaway but also some just have 2 like a 350 does so another way to tell is a 400 will always have a very small hump in the side of the block where a 350 will be totally flat next to the cylinder walls. hope this helps. just get you a mic. and use the last posts mesurements when you go looking
What do you need a mic for? If the cylinder head is off look for the small steam holes between the cylinders. It's also the best thing to do when buying a factory 400 block is check the steam holes for cracks leading to the cylinder. Cracks to the head bolt hole are common and not usually a problem.
Staging Lane
Joined: Nov 2004
Posts: 72
Likes: 0
I Was Talking To Ck The Bore Size With The Mic To See How Far Over It Is . If You Want To Get Technical About Looking For Cracks , Then You Better Have It Magnafluxed Instead Of Using The Naked Eye. A Small Crack That You Cannot See Will Expand When It Gets Hot Obviously. Better Yet I Have A $24000.00 Big Block That Will Not Need A Power Adder To Make Over 1000hp I Will Sell You . Lol
Staging Lane
Joined: May 2006
Posts: 53
Likes: 0
The 400 is nice because of the fact that it has more displacement. It doesn't take as much to make some good power with a 400 because of the cubes. The first thing that I would do is to scrap the heads on it and opt for some aftermarket heads. I would go with the 400 motor if I were you.
Originally Posted by AMS69
I Was Talking To Ck The Bore Size With The Mic To See How Far Over It Is . If You Want To Get Technical About Looking For Cracks , Then You Better Have It Magnafluxed Instead Of Using The Naked Eye. A Small Crack That You Cannot See Will Expand When It Gets Hot Obviously. Better Yet I Have A $24000.00 Big Block That Will Not Need A Power Adder To Make Over 1000hp I Will Sell You . Lol
I've seen several cracked blocks without magnafluxing them. What I'm saying is look in this very common area because a lot of cracks are visible.
Better Yet I Have A $24000.00 Big Block That Will Not Need A Power Adder To Make Over 1000hp I Will Sell You . Lol
Trending Topics
Staging Lane
Joined: Nov 2004
Posts: 72
Likes: 0
Originally Posted by 8a8mfh
Man pull your panties outta your mouth. All caps don't work as you can see.
I've seen several cracked blocks without magnafluxing them. What I'm saying is look in this very common area because a lot of cracks are visible.
Mind explaining this comment because it doesn't seem to pertain to me in any way.
I've seen several cracked blocks without magnafluxing them. What I'm saying is look in this very common area because a lot of cracks are visible.
Mind explaining this comment because it doesn't seem to pertain to me in any way.
by the way 11,000 for the big block LOL!!!! LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Originally Posted by AMS69
i did not mean anything by it either??? the big block comment is just hoping i could sell it so i can build a all aluminum small block. P.S. i never paid attn. about the caps by the way 11,000 for the big block LOL!!!!
by the way 11,000 for the big block LOL!!!!
A 400 also has siamesed bores so i'd be leary on going more than .030 over or so with a stock block without checking the block, cylinder walls can start to get pretty thin after that sometimes.
On The Tree
Joined: Oct 2006
Posts: 124
Likes: 0
From: NORTHEAST
We have two 400 blocks in the shop right now that we sonic tested the cylinders and found them to be very thin on the thrust sides which is very common the 400 blocks and we see this on some 350 blocks as well as we sonic test every block before we so any type of machine work is done.
One customer is going with a 383 and the other is going with a Dart Sportsman block and if you want to take the chance the 400 blocks they have bought I am sure they will sell for what they bought them for if interested.
One customer is going with a 383 and the other is going with a Dart Sportsman block and if you want to take the chance the 400 blocks they have bought I am sure they will sell for what they bought them for if interested.
Teching In
Joined: Aug 2006
Posts: 4
Likes: 0
From: Simonds (God's Vacation Home), New Brunswick
Originally Posted by 2000SLPZ28
i know pontiac also made a 400 but it was a big block.
SStewart
Teching In
Joined: Mar 2004
Posts: 35
Likes: 0
From: Ashburn, VA
I've been doing some research along the same lines, as I just bought an 89 GTA to build into a drag car.
From what I can tell, they only made the SB 400s in the 70s, so all those blocks are that old. Doesn't necessarily mean they can't be used, just means they been around for a while.
If I found one that looked like it might be healthy, I would definately send it to a good machine shop to inspect it maticulously. Especially before I dumped 5-10k in the rest of the motor.
If that's not doable, getting a high nickel 010 355 4-bolt and maxing it out to a 396 might be a good choice, and will keep me in a few tight spec classes.
Starting to think an LS1/6/2/7 might be a better way to go though...
From what I can tell, they only made the SB 400s in the 70s, so all those blocks are that old. Doesn't necessarily mean they can't be used, just means they been around for a while.
If I found one that looked like it might be healthy, I would definately send it to a good machine shop to inspect it maticulously. Especially before I dumped 5-10k in the rest of the motor.
If that's not doable, getting a high nickel 010 355 4-bolt and maxing it out to a 396 might be a good choice, and will keep me in a few tight spec classes.
Starting to think an LS1/6/2/7 might be a better way to go though...
Ive had a couple 400's and loved them. I currently have a 406 and as far as ease to make power its the best thing next to a big block. I started off with a bare block from a 74 Monte Carlo and $3500 later was able to put down 514rwhp/564rwtq on pump gas. Everything thats said so far is good advice. A few things from experience....do NOT skimp on machine work especially balancing. These things dont like rpm's very much and can make crazy power down low but be sure everything is balanced good, spend the extra money to have a well known professional do it. Many ppl will tell you they will run hot...well they didnt build there's right. Take your time with the block,heads,and intake...smooth out all the water passages with a dremel tool. Most everyone has the steam holes put in there heads but its really not necessary, i dont have them in my heads and its able to sit here in the SC heat and never get over 170*. Oh yeah...and if you dont got a good rearend you will before long cause you'll end up leaving the pieces of your gears/diff laying on the starting line. 
Staging Lane
Joined: Aug 2006
Posts: 56
Likes: 0
400s are great motors the 4 bolts web is weaker then the stock 2 bolts but a 4 bolt would work great on a street motor with maybe a 100 shot and a nice heads anc am setup.There are many knowin 2 bolts that live over 550rwhp but pretty hard to find a 4 bolt to do the same.If you were going to spend all that money on makin a 4 bolt hold the HP why not look at a bowtie block?I know somone had a 410 in there 79 Mailbu with a set of stock vortec heads and a 125 shot and 4500 stall and 3.42 gears car was going high 10's he put a 175 shot on it and cracked a wall since they were thin from the boring.He didnt feel like resleevin it for the 3rd time.....
good call Dzman. i'm surprised it took reading all the way to the last post to see someone mention the difference between the 2 bolt and 4 bolt blocks. if you can find one, a 2 bolt main block is the preferred choice, but a good machine shop in the know will tell the customer to have it converted to splayed billet main caps and therfore convert it to a 4 bolt. this is the best and strongest way to build a 400sbc from what i've ever read on them. the next thing to do to strengthen the block is a filler.
i had a very simply built 400 sbc years ago and it was a great motor. i loved it until it split the frame on my El Camino.
i had a very simply built 400 sbc years ago and it was a great motor. i loved it until it split the frame on my El Camino.
