73StreetRace

This was also my source of information. Very interesting book

Mike Ward

Here we go again. I knew you'd jump on this- ready for the attack and straight for the jugular.

The GM foundry worker has a very simple, logical explanation, but gave up years ago trying to dispel the myth as it seems to be too deeply ingrained in myth and legends. Seems to be a very smart guy for that reason alone.

He states that some (but not all) of the patterns molds used at the time for the front and rear of 0010 blocks had the 010 and 020 markings to denote which final casting number blocks (3970010 and 3970020) they were suitable for. These pattern molds were used indiscriminately as required, no special treatment. Similarly, a series of three numbers can be found on the front and rear of blocks of other casting numbers and again they represent the last three digits of the final casting number. No other meaning, even if you put the block on a turntable and play it backwards, no message from the dead Beatles.

There was no provision at any of the foundries to use high tin/nickel AND coordinate that with the 010 020 pattern molds.

There also was no effort made to direct 010 020 blocks towards hi perf vs. low perf applications.

Being that the 0010 block was very much the most common casting number used for 350 cu in SBCs during the 70s, it was produced in very high volume and simultaneously at all three engine plants. The logistics of pouring a different material for a small production run of hi perf block without changing the casting number AND THEN keeping these blocks separate from the low perf version with the same casting number inside the same foundry and all the way down the production line would be impossible and contradict all of GM's manufacturing processes.

It is true (confirmed by a GM second source) that high nickel and tin blocks did exist during a certain time frame, but using the 010 and 020 markings as 'proof', or the fact that a given engine came out of a high perf installation as confirmation has no basis.

It's very possible that your grannie's 2bbl station wagon with no markings was a high nickel/tin block while the LT1 with markings that you drool over is not a high content block.

mysixtynine

I am not agreeing or disagreeing with this thread. I just thought this line was funny.

" No other meaning, even if you put the block on a turntable and play it backwards, no message from the dead Beatles. "

Solid LT1

Mike, your such an expert can you tell us why GM wasted the $$$ on fitting nodular iron caps on some engine blocks but not others? These "trick" parts are always found on blocks with the 010/020 casting numbers.

Do you work in a machine shop? You seem to be an "expert" on many engine items here. I know 63 Mako does, I have put my time in at one too, it's not an easy living working in one. Can you elaborate on your experiences? I'll post 2 pictures of failed exhaust valve seats in early Chevy cylinder heads for each photo you post of yourself standing by a Rottler boring bar or Sunnen hone.

I also have a 350 block that must be defective because it has siamese bores and a funky "HD" on the side of it but no tin in the iron mix, just lots of nickle. GM really screwed that one up, it machines very poorly and takes a long time to properly hone the bores but, on the good side, it's only 4.030 and a sonic checker says I can take this out to a 4.130 bore safley

Mike Ward

My professional background and experience has been discussed before. Go look it up.

I spent enough time in the latter part of my OEM career to understand that myths and legends emanating from end users in the field who 'reverse engineer' complicated explanations for simple issues are pretty well locked in forever no matter what the true story is. Like the GM employee who was actually there on the foundry floor watching the 0010 blocks being cast, it's futile arguing. Believe what you want.

During my working career, there were two outside suppliers of high pressure fuel nozzles for the particular engine line I was responsible for. The two parts were 100% interchangeable and were commonly intermixed indiscriminately on the assembly line and also at company overhaul shops. Despite years of formal investigation that proved no difference in reliability, performance, durability and direct or indirect operating cost, some end users developed a hard preference to supplier A over supplier B and would pound the table insisting that we supply only A. Not surprisingly, there was an equal number of operators who preferred B over A and thought the others were complete idiots. We deliberately sat them next to each other at conferences hoping that some cross pollination would occur. Our field representatives would occasionally have to broker hostage exchange deals for operators within their territory just to keep the peace.

Ref, the valve recession topic- neither you or anyone else can seem to produce actual proof of a documented case of a Corvette suffering from this issue. On the other hand, there's dozens or hundreds (thousands?) that have come forward to confirm that they've never had a problem. Who to believe?

Sorry, gotta run. Seems somebody's finally broken the mysterious trim tag code of what the U and L mean next to the paint code. It's urethane and lacquer, right?

jackson

'bout as rich as a foot up a ***** ***

jordan89

73StreetRace

Maybe we should call David Vizard and ask him some questions...

63mako

Ex-aerospace engineer David Vizard, with over 3,500 published articles and 29 books (5 publisher’s best sellers) is one of the world’s most widely published automotive writers.

He is also a university lecturer, holds numerous patents and is a winning engine/car builder. In his best year he amassed a combined 169 track records, first places and championship wins, from just 8 engines. Technology he has developed has been used on everything from F1 across the board to drag race and dirt cars.

David Vizard says this in his book "Budget Building Max Performance Chevy Small Blocks:"

"The best blocks to get are the blocks that have a number 010 and 020 under the timing chain cover. These have 1% tin, and 2% nickel. The tin is used to help the metal flow better into the casting mold.

These blocks are the least prone to cracking. Also, because they pour more easily, they have the least problems with hot spots caused by porous metal. If you find a block that only has one number that's either a 010 or a 020, this means it has no additionally added tin, but does have one or two percent nickel."

Could he maybe be right and Mike Ward wrong?

Mike Ward

Very, very possible. In fact I really hope I am. It would be nice to issue the absolute statement 'all 010 020 block are high nickle/tin content and no block without these markings have it. No exceptions. None.'

Just waiting for somebody to step forward with a more credible story about the 'truth' and I'll gladly retract my statements.

L88Plus

I've got no horse in this race, but I do have a question for you, Mike. You refer to GM using the same molds for 3970010 and 3970020 blocks. Kinda hard for me to believe since the first is a 350 block and the second is a 307...
And except for a 3956618 block I now have, all the blocks I've seen with 2482 nodular caps have been the 3970010 casting with 010/020 behind the timing cover.

Mike Ward

That's not quite what I said. I mentioned the pattern molds for the front and rear of the block only.

With respect to the caps, again that's possibly a case of reverse engineering to invent an explanation. Maybe only Saginaw used the 010 020 identified end molds and Tonawanda and St. Catherines didn't. I don't know and no one else has come forward with a nay/yay. My source worked at Saginaw. From what other sources tell me, it is more likely that all three foundries used the high content material to address the machineability and bore wear concerns. If so, it would infer that there's lots of 'good' blocks out there that are being disregarded because they don't have the magic markings. If this is true, it would be more realistic to look for a range of casting dates. I don't know.

Did the foundries stop using the 010 020 markings before they stopped using high content material or the other way around? Dunno.

The single message I'm trying to get across is that the presence of high tin/nickel is not 100% connected to the presence of the 010 020 markings.

builder

Would you say that with the presence of the 010 020 markings, that it is "most likely" to have the higher nickel/tin content in the blocks discussed?

Mike Ward

Nope, wouldn't make that assumption either. Read the details of the posts above.

Clams Canino

However... a 010 and 020 surely can't hurt anything.... we've established that much.

-W

Mike Ward

I disagree with that also. It is not established that all 010 020 blocks have high content. If someone absolutely had to have a high content block and paid a premium for one solely on the basis of the magic markings, he may or may not have gotten his money's worth.

Just to throw fuel on the fire, does anybody have evidence to prove that the high nickel content makes a difference for performance or durability anyway? This should get the egos going. (flame suit on and ready)

Solid LT1

Mike, thanks for your contributions on the forum, I always need some comedy relief from the stresses of the daily grind. Some of your posts/views really make my day

63mako

Here is part of an article from Dave Emanuel in Engine
Builder Mag. It was always my understanding that the numbers 010/020 meant 10 percent tin and 20 percent nickel. I thought I was mistaken on this but that is also what this says. Invar is a 36% nickel and iron alloy. It is very difficult to machine and is dimensionally stable when temperatures increase. These properties should be shared but to a lesser degree with a lower percentage of nickel. (durability, hardness and heat dissipation) Good things on a performance build. As I said earlier you can notice a definate difference in the ease of machining 010/020 blocks when honing especially. Seems they take twice as long to hone.

Cylinder block
As with any rebuild, one that will produce a high performance engine starts with the block. In the overall scheme of things, only two types of cylinder blocks exist - those with two-bolt main caps and those with four. But over the years, dip stick position has changed, rear main seal configuration has been updated, and a variety of alloys have been used.
Dip stick position isn't much of an issue, unless you've ordered the wrong oil pan. Then you wind up with the dipstick on one side, the notch in the oil pan on the other, and an engine with a severe oil leak. Alloy content is a somewhat different matter. Thousands of high performance small blocks based on a standard alloy block casting have run successfully for years. But for maximum strength and longevity, a "high tin" block is preferable.
A block's alloy content is denoted by two figures cast into the front face, just above the main bearing bore, in the area normally concealed by the timing cover. Many production small blocks have the numbers "010," "020" or both cast into their front face, just above the main bearing bore. If both numbers are present, one above the other, it indicates that the block alloy contains 10% tin and 20% nickel. A single number, either a "010" or "020" represents the amount of nickel and indicates negligible amounts of tin.
No numbers, other than the casting numbers that are typically found beneath the timing cover, translates to only minor amounts of tin and nickel being present in the block alloy. (Tin and nickel are two metals that are commonly alloyed with cast iron to improve durability, hardness and heat dissipation.)
Although a "010"/"020" block is most desirable, it's not always possible to find one that's suitable for high performance use. Alloy composition aside, cylinder wall thickness is the overriding consideration in block selection, sonic testing is the only way to be certain that wall thickness is adequate.

Both Dave Emanuel and David Vizard confirm that the 010/020 are alloy designations. They do disagree on the pecentages. I am not sure either.

This has the same percentages listed.
http://www.nastyz28.com/faq/engine.htm

Mike Ward

I can assure you that's it's not 10%/20%.

I note also that there is a disagreement as to the purpose of the tin. One says it for machineability/manufacturing, the other for strength and durability.

Solid LT1

I would have to agree with Mike on this one, more like 1% tin 2%nickle. The baddest A** Bowtie blocks are only around 5% nickle mainly because nickle isn't cheap and you only want to block material so hard.

I was just at a friend's shop tonight where he is working on a rare GM motorsports low deck SBC block cast for NHRA Pro Stock Truck racing, that iron alloy is one ****** to work with. My friend was not in too good of mood doing the work and since the block is so rare, and a mistake might be costly, I quickly excused myself and left him alone.

I think that block is called CGI or Compacted Graphite Iron and you don't even want to know what that stuff cost!