sting66cp

I have a 350 4 bolt block, casting number 10066036. Is this possibly a high nickel block?

Solid LT1

I think the answer will be right about where it says: Hencho En Mexico in otherwords NO!

73StreetRace

If I remember correctly, a high nickel/tin block should have a 010 and/or a 020 written behind the camshaft sprocket, like this :

Mike Ward

The rumour about the 010 and 020 meaning high nickel is false.

sting66cp

Will this block be of lower quality because it was cast in Mexico?

Roughrider

Not necessarily. It comes down to quality control and training of the employees. GM casts many engines in Mexico, including the LS series. There was an article in a Corvette magazine several years ago where it showed LS engines being cast in a GM Mexican foundry, then shipped to another GM facility in Canada for assembly, then shipped to Bowling Green for installation into Corvettes.

GM sets the specifications and the plants, wherever they're located are supposed to follow through. Whether the blocks are high or low nickel content, it's GM that made the specs.

73StreetRace

Really ???

So, what do these numbers mean exactly ?

Mike Ward

Those simply represent the last three digits of the engine block casting numbers that would use that particular mold ie 3970010 and 3970020. Similar correlating numbers exist on other engine blocks.

73StreetRace

When you say "rumor", do you mean that these high nickel blocks don't exist
or only that casting numbers aren't the good way to determine it ?

Mike Ward

That casting numbers 010 and 020 do not confirm the existence of a higher than normal % of nickel in a block.

Crash80

Why is a high nickel count block so coveted, out of curiosity?

builder

I was with the understanding that a 010 or 020 cast in the block under the timing chain cover WERE higher nickel alloy content. 3970010 casting number alone did not signify high nickel, but the casting numbers under the timing cover were. The 3970010 block were a good place to "start" when looking for a high nickel content block.

Solid LT1

Once again Mike W is off base, if your block has the numbers 010/020 under timing cover and in bellhousing area in back it is indeed a high nickle/tin block. There is 2% nickle added and the 1% tin is there because the iron was tough on the GM machine tool bits and the tin acts as a lubricant during the machining process and also gives a little more ductility to the iron (less likely to stress crack.)

The real high nickle blocks were all aftermarket from GM performance and most have a Chevy Bowtie on them with the letters "HD" in the emblem for quick identification.

I'm not sure about current foundry processes but during the 80's and 90's the "Henco en Mexico" blocks were inferior iron content and I wouldn't use one for a performance build-up of any kind.

Just like his opinion that you don't need hardened exhaust valve seats in older heads, his 010/020 block post is dead wrong!

Good luck in trying to find one of these blocks nowadays, for years the circle track crowd has known of the 010/020 casting numbers and most good cores are long gone! They were found in HD truck motors, LT-1's and L-82 enignes. These motors should also have the good nodular iron 4 bolt main caps with the 24XX numbers on them rather than the 3XXX nubers of a STD engine block. I did observe a original 350 two bolt motor at a friend's shop that also had 010/020 casting on it so maybe a decent search would come up with a winner for you.

Solid LT1

That block is a WINNER it will also have 010/020 cast in the bellhousing area of it. Good block for a 450HP motor build-up.

Rich's'78

How much is a high nickel L-82 block worth more than a standard L-82 block?

Mike Ward

Again with the chip on your shoulder.

A former GM employee who worked at the foundry came forward and confirmed that the 010 020 numbers had no connection to a high nickel or tin content. No connection. Another GM employee came forward and offered that while these blocks do exist, the extra % of nickel and tin is in the 1/10s of a percent- and was done to address high field warranty costs. The program ended with no positive results being shown.

Please show me GM documents to prove me wrong and I will retract my post. Same goes for the burnt valves seats myth.

sting66cp

It also has ths stamping on the deck surface near the front of the passenger side head.

MI025IVP

63mako

but your a little off as well. Those blocks were made in the early 70's. Late 70's blocks were lower in nickel. The alloy composition of the early 70's blocks is vastly superior to the later blocks. It is true also that the harder alloy 010/020 while wearing slower also was hard on the tool bits used in machining and more time consuming to machine which is why the bean counters at GM reduced the nickel content, to save on machining costs and tool bit replacement. It also made you have to buy a new block instead of having minimal cylinder wear and being able to rebuild it. Those early 70's blocks are a great starting point for a performance build if you can find a good one. Mine is a 73 L82 high nickel block.

CheezMoe

To get back on the OPs subject and subsequent questions, FWIW I have the 10066036 block. It was in the car when I bought in it's stock target master form. I pulled it and took it to a reputable race engine old school machine shop type who builds tons of boat, circle track and sprint car motors. He told me the nickel content in those blocks is more than adequate and that he has used them many many times. We kept it and he bored and machined and built a 383 with SCAT 9000 crank and forged rods and pistons. (it's mild - ~400HP ). Have ~2500 WOT miles on it to date!

63mako

Who are these employees? Were they connected to the metalurgy procurement process, alloy analysis or verification or line workers? Do they have any credentials that legitimize their claims? If not it is hearsay and not to be taken as fact.
Here is a fact. I have machined dozens of the early 70's 010/020 blocks and the later blocks without both 010 and 020. You can tell the difference in the hardness when machining (decking, honing) these take forever to hone. The lack of cylinder wear is also apparent on similar mileage blocks compared to the later blocks even though they used the same ring packs. This I know from 35 years of personal, hands on experience but I have no GM documentation to prove it. Please show me GM documents to prove me wrong and I will retract my post.

Edit: 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."