Yesterday a gentleman that's been working in the automobile salvage business for 40 years informed me something about '62-'65 870 blocks I've never heard before. He stated he's seen differences in the font on the '870' part number castings for known Corvette and known non-Corvette blocks and casting date codes. According to him, the Corvette blocks have a more pronounced font with raised (taller) numbers and use 1 digit to represent the year on the casting date, non-Corvette used 2 digits. I immediately disagreed with him about the date difference. I have an 870 block that came out of a truck, so I was told (suffix is 'S' after the build date stamp) with a 1 digit year in the casting date. Appreciate any feedback. Oh....he wants $1500-$1600 for the known Corvette blocks and ~$400 for known non-Corvette blocks. Ouch!!!
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Re: Differences in 870 Blocks?
Flint blocks (all Corvette, but also many other cars/trucks) have the 1 digit year, while Tonawanda blocks have the 2 digit. Tonawanda blocks may or may not also have a difference in the casting number font. -
Re: Differences in 870 Blocks?
Also, Tonawanda small block castings were NEVER used for Corvette engines - just Flint blocks, but millions of Flint blocks were installed in pass. cars and trucks, so just because you can ID a Flint block casting doesn't mean the block was from a Corvette.
If the stamped engine date/build code is still on the deck, one can usually identify the model year, original horsepower rating, transmission type, accessory configuration, and what type of vehicle it was originally installed in - pass. car, truck, or Corvette because all had specific build codes for specific HP ratings and accessory config.
For example a 327/300 without AC or PS mated to a manual trans. built for a Corvette has a different assembly code than an identically configured 327/300 destined for a pass. car.
This guy is giving you a big snow job.
DukeComment
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Re: Differences in 870 Blocks?
Duke,
Never say Never. During the C3 era (1969 to 1974), and maybe before and after, unfinished Tonawanda cast small blocks were sent to Flint for machining and assembly. Some of those were installed in Corvettes and have the casting number 3970014. Saginaw cast small blocks of the era have the casting number 3970010. Those of us who do C3s all the time are well aware of this, and it is included in the appropriate TIM&JGs.
Our investigations revealed that this was done to ensure there was an alternate source of raw castings in the event Saginaw had casting or delivery issues. It is just a guess on my part, but I find it hard to believe that someone suddenly decided in 1969 to begin doing this. I suspect it went on a lot more than we know or are willing to admit. But WTFDIK.
TerryComment
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Re: Differences in 870 Blocks?
Fred------
Not all Tonawanda castings use a 2 digit year code for the date but most do. However, it's very easy to discern the difference between a Tonawanda and Saginaw-cast small block, including the '870'. The Saginaw (and Flint-machined) block will have a 1/8 NPT plug above the timing cover on the front of the block; the Tonawanda-cast (and Tonawanda-machined) block will have no such plug. That is the easiest way to tell them apart.
The Tonawanda-cast block will usually have a large "T" foundrymark cast on it, often in the vicinity of the casting number. The Saginaw-cast block will usually have no foundry mark and, certainly, no "T".
If there is an engine code on the stamp pad, the Tonawanda-machined block will have a "T" as a prefix. The Flint-machined block will have an "F" or a "V".In Appreciation of John HinckleyComment
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Re: Differences in 870 Blocks?
And the Tonawanda cast and Flint machined block will have a 1/8 NPT plug above the timing cover on the front of the block.TerryComment
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Re: Differences in 870 Blocks?
Duke,
For a very short time (maybe only several days) during the 1965 production year 327 Tonowanda blocks with a 3858180 casting number were installed in 1965 Corvettes due to a breakdown at the Saginaw Foundry.
DaveComment
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Re: Differences in 870 Blocks?
Fred, go back and tell he's right and then go through his "passenger " car blocks looking a Flint casting in your desired time frame and give his $400Comment
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Re: Differences in 870 Blocks?
Terry, I think that I have a Townawanda cast and Flint machined block, I have the 1/8 NPT plug on the front on my 0014 block. Are all 0014 blocks considered to be cast at Townawanda? Warren and I are going to have our cars at the upcoming Regional meet in Sacramento, I am looking forward to seeing you there and hope that you have some time to take a look at my cars.Comment
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Re: Differences in 870 Blocks?
I have a "3970014" Tonowanda block with casting date "E 16 70" for my 1970 Camaro SS350 (long term project, 1990 to date so far) that I bought at the Carlisle, PA, swap meet several years ago. The partial VIN is stamped near the oil filter area on a cast surface so it is very difficult to read but I know it was from a 1970 Camaro SS350 because of the "N" (Norwood) in the partial VIN. Unfortunately the front "pad" is stamped "T0518CRE" for an automatic. I was and still am looking for a "CNJ" stamping for a 4-speed.
I have searched and studied the "3970014" block for over 20 years and have never seen one from Flint.
DaveComment
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Re: Differences in 870 Blocks?
As to the font size on the 3782870 casting, the '65 TIM&JG allows....
"Approximately midyear the vertical height of the casting number was reduced due to the introduction of new molds. However, the smaller height number did not completely replace the larger number. Both appear to the end of 1965 production."
Here's a late '65, VIN 23321 cast G25, F0713HT with the large (most common, IMO) font.Last edited by Wayne M.; August 13, 2011, 12:42 PM.Comment
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Re: Differences in 870 Blocks?
Greg-----
There are several other factors that need to be considered.
1) Is there a large "T" found in the vicinity of the casting number or elsewhere on the casting? If not, is there a large "K" found?
2) What is the casting date on the block?
3) What is the prefix of the engine code found on the stamp pad? Is it a "V", a "T", or a "K"?In Appreciation of John HinckleyComment
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Re: Differences in 870 Blocks?
Joe,
There is a "T 1" and then a "CONV 2" on the right rear of the block, the casting date on the block is C 2 72 and the prefix is a "V". GregComment
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Re: Differences in 870 Blocks?
Joe, this is a complete aside, but another interesting thing about my 72 with the 0014 block is the fact that it has a 3.70 rear gear mated to the "standard" M-20 ZW4 transmission. It is an LT1 and from what I understand from the ordering and Power Team guides of the time, if you ordered an M-20 the standard gear was a 3.55, a 3.70 gear was optional. I have the build sheet, the dealer order sheet, the POP and the window sticker. Both the build sheet and the POP show that the car came with the 3.70 rear gear and the M-20 transmission, however the window sticker and the dealer order sheet do not call out the 3.70 rear gear, in-fact the dealer ordering sheet calls out the standard ZW4 transmission and the 3.55 rear gear. I saw another 72 convertible LT1 like mine that Pro Team sold a while back and it was the same situation, what do you make of this? Thanks, GregComment
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Re: Differences in 870 Blocks?
Greg-----
Then, also considering the pipe plug you have above the timing cover, I would say that you have a Tonawanda-cast block that was machined at Flint. While these may be quite rare, I'd say this is one.
The only other possibility that exists is that this is a Tonawanda-cast block that someone "converted" to Flint-machined block by restamping the pad and adding the pipe plug. However, I strongly doubt that occurred. For one thing, the 3970014 block is far more rare than the 3970010 block which would generally be considered correct for your application and which is plentiful.In Appreciation of John HinckleyComment
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