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Discussion Starter · #1 ·
Can you guys/gals identify this engine for me? I believe it to be a SB400, but just back me up. TIA
DJ

In the back left corner by the oil filter;

010
020
161

On the sice of the block;

509

And on the back of the engine;

010 H17
 

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DJ,
There should be a casting number on the block surface directly behind the drivers side cylinder head. If the motor is still in the car you should still be able to see it. Let us know what this number is to be certain.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md
 

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DJ,

This block should indeed be a small block 400; the casting nubers that Bill directed you to, should read 3951509. (The last three digits being reproduced in the side, as "509") And as he stated, finding these numbers will indeed identify it, as this casting was only used for 400s, both two bolt and four bolt versions.
 

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DJ, according to the book CHEVROLET SMALLBLOCK INTERCHANGE, 400s have the following casting numbers on the upper left side of the bell housing flange:
3951511----70-74
3951598----70-71
3951529----70-80
3951509----74-80
3973493----71-73
3998997----72-74
3932882----75-76
14010509--79-80
I just went out and looked at 4 of the 400s that I have and all 4 are 3951511 with dates of Jun and Sep 70, Feb 72, these 3 are 4bolt blocks, and the 4th has a date of Aug 72 and is a 2 bolt block. The Aug 72 would have gone in a very early 73 car. Everything I have read, everything I have been told and everything I have personally observed seems to confirm that 400s for 70-72 cars were 4bolt only and 73-later cars had 2bolt only even though both 2 and 4bolt blocks sometimes shared the same casting numbers. As you can see from the above engines that I have, this is true. Two things for sure, all 400s have steam holes in the deck between the cylinders and all have the larger crank bore for 2.65in. mains.

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[This message has been edited by DZAUTO (edited 02-16-99).]
 

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I read somewhere that 400 SB's have 3 freeze plugs instead of 2. My 400SB which is a 72 vintage with 4 bolt mains has 3 and the 350 sitting next to it has 2.
 

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Sorry, I forgot to mention something about the 3 freeze plugs. Yes, basically sb400s have 3 plugs on each side. Although there is an exception. Late production 400s have provission for 3 plugs but some only have a boss where the center plug would be. The 350s do not have a center plug or a center boss. Unfortunately, I cannot give you a casting number for the blocks that have the center boss without a plug. I have personally seen these blocks with the center boss.

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[This message has been edited by DZAUTO (edited 02-17-99).]
 

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Hey, DZ, wanna get rid of one of those four bolts?
 

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Discussion Starter · #10 ·
Yeah thanks for the info. Its just a short block. Its a nice block, totally cleaned it, it was sitting for a while, but looks great now. For a short block, how much is it worth without the pistons, but with crank and connecting rods? I have a friend that wants it (I have trouble letting go of it since I got it for free).

I got the #'s, it is 3951509, how do I tell if its a 2 or 4 bolt? It also says L77

[This message has been edited by DJ (edited 02-17-99).]

[This message has been edited by DJ (edited 02-17-99).]
 

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DJ,

The circle track sprint cars here in N. Calif. have about exhausted the 400s that were available here. So, the grave-yards are getting $250 for a rebuildable block.

I happened to be in the right place/right time on Monday, and bought a running 400 (car and all) for $150.

Two years ago I had a guy pester me for months, until I gave in and sold him another running 400 that I had ($250). I then kicked myself for doing it. You sound like you really don't want to sell yours either....

If you build it yourself, and set it aside; it'll give you a reason to snatch up that next project car that you run across!

The two bolt / four bolt question .......turn the block over; if the main caps use two bolts, it's a "two bolt".
 

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I've found that 2 feez plugs per side indicates 2-bolt mains and 3 freeze plugs per side indicates 4-bolt mains on a 400. 4-bolt blocks were used from '70 - '72, but I have heard of 1 legit '74 Monte Carlo with a 4-bolt block as original, although I think it was a bit of a fluke. Even the light duty trucks from '75 - '80 used only the 2-bolt blocks.
 

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Scooter,
The only 400 I have left is a 2bolt and I am kicking myself now for not latching onto all the 2bolts that came my way in the past. Nothing at all wrong with a 4bolt, but for a SERIOUS sb400, the best way to go is a 2bolt and then use aftermarket splayed 4bolt caps (all the 4bolts that I have are in cars, a pickup and a boat).

DJ,
I wouldn't let it go. But if you do, assuming the block and crank are useable, MINIMUM, $100 for each. The rest is worth very little, not even the rods. When you build a 400 you really want to at least use the 5.7in 350 rods, and git rid of the shorter 400 rods. There are plenty of pistons, at a good price, available for a 400 with 5.7 rods.

Cam,
I promise, 2 or 3 freeze plug blocks will not necessarily indicate 2 or 4bolt. I have 2 blocks with the same casting number, which are 2 and 4bolt and they have 3 plugs. The best way to determine 2 or 4bolt is to remember that 70-72 cars had 4bolt only and 73-later cars have 2bolt only. The 2bolt block I have is an Aug 72 casting which means it PROBABLY was in a very early 73 car. And that 74 Monty, for me to be convinced, I would need to see a casting date of July 72-earlier, AND the VIN number of the 74 Monty on the stamp pad.

Everybody,
If you are going to build a sm bk, you really can't go wrong with a 400. There is no substitute for cubic inches, and if it is necessary or desireable for whatever reason to have a sm block (such as a 100% bolt-in swap for a 57 Chevy) then it is the perfect engine. I just do NOT see over heating problems if the cooling system is in good shape. I don't mean to offend, but I ablolutely do not understand the 383 reasoning. Leave that 400 crank in the 400 block, bore it .030, BAM! 406 inches, and the rebuild cost is within a few $ of a 350 rebuild!

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I have a 2 bolt right now that I just rebuilt as a 406. It's sitting in my 70&1/2 Camaro RS just begging to be fired up! I used stock 400 heads (mistake, I know) will be upgraded in the near future. I used Domed pistons with 5.7" rods and have a Holley 750 CFM double pumper on top of a Weiend Excelerator intake with a Muncie 4 speed behind it. Should go pretty good with a different set of heads. Gotta finish the car first, though. Front end is done, rear end is near done, then body, paint, interior. Then I will spend some money on the heads. Anyway, always looking for SB400's.
 

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Discussion Starter · #15 ·
Hey thanks for the info! I have another question...I've heard of kits that punch the SB400 .060 over, and have 434 cubic inches? What's the deal on these? race only? Anyone make a kit for it? looking to make my next project vehicle more race than street. Thanks
 

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DJ,
The 434 is created by using a 4" stroke crankshaft.

You must use 6" rods with this crank, and they have to be shaped to clear the camshaft. (The 3.875 crank will clear with just these rods, but I seem to remember that you also need the use of the small circle cam to achieve the clearance needed with this crank.)

The cylinders will have to be notched, and you'll need to seriously massage the oil rail. You should be warned that you will likely break through to the fluid passages while attempting it.

The 4" stroke and 6" rods leave little space for pistons. Expensive things come in small packages.

This is why they created "Big Blocks". Everything is spaced and beefed to accommodate the high cubes and high HP. You can reach the power you want, with fewer dollars.
 

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All right, lets start the big block small block bashing. I would think a 434 small block would cost as much as a 540" big block. Less wieght the substitute for cubic inches. You big block guys always consider a small block easy prey dont ya. HA HA HA
 

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Hey guys, I like BBs as well as SBs, I would like nothing better than to have a custom 500hp+ 502 in everything that I have. But, you know, it's called $$$$$$$$$$$. As just one example, Corvettes did not come with a BB until 65, which means that the 63 would be the first Vette that a BB COULD be easily installed in. Mine is a 56 and they were only designed for a SB. So rather butcher a classic, I stayed with the biggest cubes that I can get under the hood and retain a 100% bolt in swap. I even use those early 2 1/2in rams horn manifolds to retain a pseudo stock appearance.
DJ,
I wouldn't even consider a 434sb, mainly because of the $$$$$$$$$$. As has been mentioned, this puts you in the BB price arena, not to mention the extreme risk to durability. I have serious concerns about the 420 I built for the boat. This summer will tell the tale.
As far as building a max 400SB, I think probably the safest way to go is to just build whatever you can logically afford in a 406. Otherwise, if you really need a lot more, then a BB is difinitely the next step. And if $$$$$$$$$$ is not a problem, why spend it on a SB. Yes a SB saves weight, but if you really have the bucks and want to save lbs., maybe an all aluminum BB is the answer. But my budget won't play that tune.

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I have a new question to twist into this 400 controversy. I've always heard that the 509 castings were made of a high nickel alloy and thus were more desireable. I have a 2-bolt version of this block. A guy interested in buying it recently told me that it(the alloy block) was actually a different casting #. I beleive my source to be reliable. What's up? IS either of us right?
 
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