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Discussion Starter · #1 ·
I have an Engine Block w/ casting # 3855961 with a 4-bolt main. I can't locate the date code and it looks like the VIN is missing. Any idea what this engine is? Is this a 1966 L78 375hp 396? ANy help locating the date code and explain why the VIN is missing?
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Locate the rear intake China wall, also known as the rear intake manifold. Find the code date of the Chevy big block. The code is a letter followed by three numbers and is above the bell housing.

With the current picture and condition of the deck surface, I can't tell if that deck has been resurfaced/decked which could eliminate a deck stamping.
 

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Looks like a rusty old drag race block that has been beat to death :) It has been o-ringed so it was probably used with a blower or maybe nitrous and has almost certainly been decked at least once if not more. Looks like somebody has cut some pretty big valve reliefs in the cylinders too.
 

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What Bill said^^^ Looks like a candidate for anchor duty!
 
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The casting date on a 961 block is located on the passenger side between the engine mount and starter area.
 

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Yes, that is what is what remains of the casting date. A 4 bolt 961 block would have been produced between approximately April and July 1966 for use in a L78 or as a replacement block. An over the counter service block would have been stamped with a date code on the pan rail near the starter. That is still a possibility.
 

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Discussion Starter · #8 ·
Locate the rear intake China wall, also known as the rear intake manifold. Find the code date of the Chevy big block. The code is a letter followed by three numbers and is above the bell housing.

With the current picture and condition of the deck surface, I can't tell if that deck has been resurfaced/decked which could eliminate a deck stamping.
Yes, that is what is what remains of the casting date. A 4 bolt 961 block would have been produced between approximately April and July 1966 for use in a L78 or as a replacement block. An over the counter service block would have been stamped with a date code on the pan rail near the starter. That is still a possibility.
I found this on the pan rail. What does this tell you?
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Discussion Starter · #9 ·
Yes, that is what is what remains of the casting date. A 4 bolt 961 block would have been produced between approximately April and July 1966 for use in a L78 or as a replacement block. An over the counter service block would have been stamped with a date code on the pan rail near the starter. That is still a possibility.
Found this on Pan Rail. So what does this mean then?
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That tells me the block was produced in Tonowanda, July 6. It was a service replacement block, not a complete engine, and would not have been installed in a L78 Chevelle from the factory. It is not the original L78 engine out of someone's 1966 Chevelle. It would not have had a deck stamp and VIN.
 

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Discussion Starter · #11 ·
That tells me the block was produced in Tonowanda, July 6. It was a service replacement block, not a complete engine, and would not have been installed in a L78 Chevelle from the factory. It is not the original L78 engine out of someone's 1966 Chevelle. It would not have had a deck stamp and VIN.
Thanks, sounds like I got to the bottom of this. I picked it up the other day, but didn’t agree on a price yet. Is this block worth anything in its current condition?
 

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For someone with a real 66 L78 car missing its original block, if they want to have what the dealer would have put in it under warranty, they might be interested in it. Or someone building a "day-2" car. As to value, very hard to say without having it checked at a machine shop first and getting all the condition details for a buyer to take into account.
 
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Looks like a rusty old drag race block that has been beat to death :) It has been o-ringed so it was probably used with a blower or maybe nitrous and has almost certainly been decked at least once if not more. Looks like somebody has cut some pretty big valve reliefs in the cylinders too.
Based on Bill's observations, I'd guess the value is very near zero.
 
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