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Ground up engine build - block differences?

5K views 19 replies 10 participants last post by  X-77 keith 
#1 ·
So I'm building a SBC from the ground up - is there a performance difference from one SBC to another? I think I have a block from a '74 truck with 4-bolt mains. Is this a solid platform for my build or should I go a difference direction?
 
#2 ·
You can't pick a good block base for a given build just by using casting number, date, year, model or almost any other identifier as being 'better' than any other block.
Each block may have a given feature you wanted/needed, such as 4-bolt mains, but that still doesn't mean it's a good base for a build. And actually, many 2-bolt blocks with the addition of a good aftermarket 4-bolt retrofit are actually 'stronger' than any GM 4-bolt system ...
GM cast literally millions of 4" bore blocks with different casting design or features and folks have build successful performance units from nearly all of these offerings.

Selecting a given block for a base depends more on the quality of the casting, machining procedures, it's past care and the service it has been subjected to if it is a used block from an unknown source.

The quality of the casting refers to how well the core systems was aligned and mated prior to the actual pouring of the metal.
Some block exhibit larger amount of variance (often called "Core Shift" be some) than others.
These variances can cause issues, such as differences in the wall thicknesses in the cylinders that can lead to premature failure of the wall when subjected to 'race' loads, and other problems for performance builds.

The quality of the machining procedures also effects the blocks usefulness for use.
Odd variances, like lifter bore(s) being offset or out of alignment to each other and/or the cam centerline.
Poor machining can cause engine stresses and issues that could lead to early failure under performance use and waste all those expensive parts.

Best suggestion would be to take the block you have now to a competent machinist or engine builder or your choice and have them check it over to make sure it is a sound base for your build.
Most charge a very reasonable fee (compared to having to build another engine) to do this work and many will roll the charges directly into the machining fees they charge do the other work required to prepare a good block for performance use.
If the block checks out then they can start the "Blueprinting" procedures and machine work to turn it into a great base for building reliable HP for you.

If you're really serious about building a 'Go-For-Broke' high HP SBC - you are often better off starting with a dedicated GM or aftermarket performance block.
The costs of machining an old stock block can quickly add up, and that money is often better spent on a known performance designed new block.

Hope this helps.
 
#3 ·
Some people say only use the blocks with the 010 casting due to the higher nickel content. Some use only four bolt blocks. I have used two and four bolt blocks, 010, and 020 blocks and only thrown one rod "seven years afer build daily driver car with a sixteen year old boy driving" . It all depends on the quality of the build, parts put into it, ad how it is run. If you use junk parts, you will prob get junk results. If you are going all out race, then you may want to look into a Dart block " not bad for the cost".
 
#9 · (Edited)
thanks for the help and replies - you guys are great. Looks like my casting number is 8970010 and engine pad stamped V103(or 8?)1TMM. Anyone know what I have my hands on?
The casting is actually 3970010 - a common 70's SBC casting. Came in both 2 & 4 bolt, with HP flavors in the 140~300 ranges depending on year(s) and application(s) ...
The Suffix is V1031TMM - which decodes the engine as;
V = Flint Engine plant assembly
10 = October of the casting date year - which means if it 'is' a 1974 truck it was from, then the casting date would be in Oct. 1973.
31 = Happy Halloween! or otherwise known as the 31st day of the month ;)
TMM = RPO-LF5 - 350CI, 145HP w.single Rochester 2-Barrel carb, Automatic trans and installed in a 1974/75 C-10/C-1500 2-wheel drive pick-up ...

Somewhere on the same little pad you got the Suffix (V1031TMM) from should be the 'Partial' VIN.
This will be a series of letters/numbers to designate division/year/plant/sequential VIN number.
May look something like C4U1xxxxx or close to that ...

Oh, and that 010 - 014 - 020 - 512 - 519 - 532 (et all) that you see cast into the front/side/rear of castings has Nothin' was-so-ever to do with the metallurgical composition of a given block :noway:
It is the sub-core identifier used at the casting plants to be sure the basic casting has the proper features for a given casting application ...
Even the late-GREAT "best-est" engine builders in the whole world knew this - you'll never read anything from 'Smokey' or the 'Grump' referring to using these casting markings as a designator of a good starting point for a given build ;)
They all will tell you to use the industry-standard of 'Brinell-testing' if you are concerned with a given core being 'softer' than any other unit ...
And ... since GM never really changed the casting metallurgy from the beginning of casting of SBC's in the mid-50's through the end of production - it is almost a mute subject in selecting a given core :thumbsup:
 
#6 ·
if it really came out what you say it will be stamped 010 in timing cover area --good block -but only good machine work and assembly makes it good after that--bore with matched pistons-torque plate hone -chek line bore-true deck or zero deck for power-just because its 4 bolt dont mean its better-most 2 are truer than 4 i ran a 2 bolt 400 at 700 hp level that has run for years with good machine work and best internal parts
 
#7 ·
"2482" cast into the 3 center caps is a plus, those are nodular.
A lot of folks search for the 010/020 under the timing cover...supposedly slightly higher in nickel and tin for hardness and machinability...but I've heard from folks that worked at GM's foundries who said they mean nothing.
Earlier blocks are generally better, later stuff didn't need as much beef since they were low power smogger engines.
 
#10 ·
Jaw-dropper information John. Awesome too.
 
#11 ·
John
I am not trying to start an arguement, just stating that I have seen in a few books that they talk about the 010 ad 020 castings. One book was How to Hot Rod Your Big Block Chevy, and How To Hot ROD your Small Block Chevy. These are both very old books and don't know where they got ther info, or if it is true or not. They state that the numbers are for nickel content.
I also have seen this info in Jason Scott's " Camaro Restoratin Guide 1967-1969" , published in 1997. On page 155 he states "Code of intrest is casted the front of this 350-cubicinch V-8 block. "010" here designates the "nickel" content of the cast iron from which it is formed10 pecent . Proformance engines, like z/28 302 and L78 396, often used 20-percent nickel content, which resulte in a stronger, more distortion-resistant block. Small-block V-8s were often cast with an "020"code in the timing cove." This is the caption under a picture of the cast 010.
Once again I am not saying that you ae wrong, but just showing that their is some confusion on the subject. I worked in a auto machine shop out of high school and think I rember hearing the same thing from a few of the engine builders. They have since passed, but I wonder where this all started from. The casting does'nt stop nor make me feel bette about using one block over the other.
 
#18 ·
I also have seen this info in Jason Scott's " Camaro Restoratin Guide 1967-1969" , published in 1997. On page 155 he states "Code of intrest is casted the front of this 350-cubicinch V-8 block. "010" here designates the "nickel" content of the cast iron from which it is formed10 pecent . Proformance engines, like z/28 302 and L78 396, often used 20-percent nickel content, which resulte in a stronger, more distortion-resistant block. Small-block V-8s were often cast with an "020"code in the timing cove." This is the caption under a picture of the cast 010.
Jason should stick to good research and facts, not just parroting what he hears from others. The "010" and "020" cast in the timing cover area have nothing to do with grey iron metallurgy - they only identify that front bulkhead core pattern as being used for both the 010 and 020 (307) blocks.

:beers:
 
#12 · (Edited)
I've read a lot also - but, a long conversation with a Tonawanda Engine Plant Manager at a technical meeting - and then a follow-up tour with him in the 70's - completely changed my understanding of the 'How & Why's' of castings and the designations on them.
Some of the information is there for production demand flow, some of it is for QC trace, some of it is for machining set-up, and some of it for assembly coding - BUT ... ALL of it is strictly for 'adjustment' of inner-department costs during and after a given engine is produced and in subsequent dealings with that casting ;)
When they produced a given casting it was due to production demand and they had no idea if the final engine it was going to be used in was a Camaro or a Taxi.

Straight from 'Howie's' mouth - 'The metallurgy is a set "GM Standard", established in the 50's for a consistent production product, and and had not been changed (or adjusted) for any reason since'.
This was/is true for ALL castings at a the plants - be it a Six or a V-8, an Intake Manifold or a Head ...
This was a continuous batch casting process, so additional materials where added to the furnaces constantly while casting was underway and the materials were drawn off according to mold line needs.
Any 'odd' casting demand was farmed out to a "Job Shop" vs. trying to change a given formulation for these huge production facilities - just think of the risk to production if an 'odd' batch of material got out into the production area and was used in the 'wrong' casting :eek:
He also stated that they routinely "recycled" void, damaged and miss-machined units (after 'backcharging' the given department ;) ) right back into the Grey-Iron Central Foundry Group for use on ALL castings being made - no matter if it was for a Chevrolet, a Pontiac, or a Buick ;)

I was able to discuss the casting mold set-up and technology with him - some pretty impressive stuff - and the series of methodological processes that furnish the finished castings with the designed Young's/Tangent modulus needed for a long and happy service life as a engine block - :cool: stuff to an Engineering Student :yes:

This is all just first-hand information relayed from a person that was in charge of and managed a GM Grey Casting plant system.
And by no means intended to stop anyone from believing what they read in a book from someone that hear something from someone ...
 
#13 ·
Like I stated before, I'm not saying you are wrong, just pointing out that this story has been told for years like the Loch Ness Monster story. I would think that a person publishing a book should know their stuff. I would not doubt a former engine foundry plant manager on his knolage of his job. I am a firefighter, and I would hope I know more about putting out fires than my mail man.
 
#15 ·
Like I stated before, I'm not saying you are wrong, just pointing out that this story has been told for years like the Loch Ness Monster story. I would think that a person publishing a book should know their stuff. ...
Keith - never took it as a 'right' or 'wrong' thing :thumbsup:
Just after a few years of saying that the 'ol 010 "story" is a bunch of bunk I thought I might take the opportunity to elaborate a little ;)

As far as the "would think that a person publishing a book should know their stuff" ...
Have you read some of the Camaro books written by some 'experts' :(
Certain authors are better than others - but let's just say that some of them don't let facts get in the way of getting their book out to unsuspecting subjects on schedule :p
Even guys like Jerry have made mistaken assumptions in their publications - but, he also makes every attempt to publish corrections in newer printings of each book :yes: - some others haven't ...

I issued a challenge (quite a while back) to some questioning this information to find anything in print (or published information) issued by the any of the GREAT Chevrolet engine guru's - like Bill Jenkins, Smokey Yunic, Rick Voegelin, et-all - or anything from GMP/Chevrolet Racing - that gives this explanation of the casting identifiers. No one has come through with anything I've seen :noway:
I never even heard anyone state that the markings meant something about the metallurgy until the late 90's or early 2000's - I have no idea (well, I have some :p ) who even started espousing it - must be one of the "Inter-Nets" thingys :p

If you just think about the process flow - After the cores are assembled and banked for iron pouring the line workers can not see into the mold to check for identifications internally - so they just pour the materials furnished through the mold line supply system into the scheduled part number molds on the line, they didn't know the final assembly state-of-tune at all, just the production part number for that casting ...

I was told that there were actually 'special' metallurgical blends at times - but all of these were very early production castings (pre-70~71) when the '010' started to show up in castings ...
And none of these 'special' irons were ever intended for production casting use - they were test alloys for engineering purposes and were used in assembles that were carefully tracked by GM for decisions in production.

I received a PM years ago saying there was a good posting on NastyZ (I think?) from a GM guy also stating the magical 010 info is bunk - but truthfully I never did search it out :eek:
I was already convinced this 'common-knowledge' was wrong way before I heard about that thread ...


I am a firefighter ...
I always wanted to be a Fireman - maybe when I finally grow up :cool:
 
#14 ·
Sheeze John, Back in the day (early 70's) us kids heard those rumors too about high nickle blocks. My L78 block died in 1975. It burned a quart of oil every 500 miles, even when I wasn't rat-racing.
The block had every honing mark in the cylinder walls and no ridge. I've never given myself credit for it even though I was anal about maintenance. Just assumed it was as rumored, high nickle.
 
#16 ·
OT: Next time anybody has a chance to talk to one of the foundry higher-ups, ask them how many blocks they think made it out of the foundry with the casting number upside down. I have one in my shop, 3970014 casting number that is this way - numbers can be read when looking from the block end instead of the tranny end. It's the only one I've ever seen. I'm guessing it should have been recycled at the foundry.
I figure some Aussie will want it some day...
 
#17 ·
I will side with John. My family has owned cutting tool companies that made drills used by GM to machine blocks since the 60s. I now work for another company involved with machining blocks and heads. GM has never changed the metallurgy. I think where everybody gets confused is Chrysler blocks had higher nickel content than GM thru the years.

AS long as OP gets a hold of a nice seasoned used block and has it machined properly and assembles the engine correctly, it won't matter what block he uses if it has the bosses and features he needs and wants.
 
#20 ·
John
I agree with your statement. The book is an Ok reader, but I have not learned much from it that you could'nt learn from going to cars hows and talking to Camaro owners.
 
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