I got all the readable numbers off my motor and im trying to figure out exactly what it is. Can anyone help me?? In front of the head on the right side of the motor there is a machined surface with "V1203TOD" stamped on it.On the back of the block (inside the bell housing) on the left side it has "H32" stamped on it, and on the right side it has "010" & "020" stamped. Also on the back of the block (on the top side) it has "24 GM 3970010" stamped on the left side and on the right side next to the head it has "J 121". Any and all information would be greatly appreciated.

 

the "010", "020" means that it's a high nickel block, which is a good thing.. the "397010" means it's a 350 from the late 60's to the mid 70's, and it's the very same block that the DZ 302 in the 69 Z/28 and the LT1 350 in the 70 Z/28 was based on. but it was also used in some pretty unglamorous applications like luxo cruiser Caprices with a 2 barrel carburetor and about 150hp and dump trucks.. it can have either 2 bolt or 4 bolt main caps, but the only way to know is to pull the oil pan and take a look. it's a very good block for a performance build, but not really rare or valuable.

 

From what I was told, Its a 4 bolt. I'll be pullin it apart here before long for an overhaul so ill for sure find out then. Im also curious as to what the hp and torque is for this motor from the factory?

 

All that those numbers will tell you, is what THE BLOCK came from. They will NOT tell you what THE ENGINE "is".

THE ENGINE is composed of a BLOCK, crank, rods, pistons, heads, cam, machine work, and so forth. EVERY BLOCK is interchangeable with ALL HEADS, all cams, could have had any pistons at all put into it, and so on.

3970010 is the single most common 350 block casting number there is.

J121 means THE BLOCK was cast on the 12th day of the Jth month (10th, October) of a year ending in 1. THE BLOCK probably came in a 72 model vehicle.

The odds of a 40-yr-old BLOCK that's in some vehicle other than the one it came in, but still being assembled as the identical same ENGINE that it originally was, are so tiny as to be quantum-mechanical. Laughably small.

Bottom line is, you have a plain, common, ordinary, garden-variety BLOCK. It is not particularly "desirable", nor "undesirable" either, any more than any other 70s block with the chances of the crappy quality control from that era. The numbers stamped on it contain ZERO information about THE ENGINE that is built around it. There is no point in following this line of inquiry, because whatever it tells you, only applies to SOME OTHER ENGINE built with that block a LONG time ago, which no longer exists.

Far more important than tracking down what application the stamping code is for, is the CONDITION of the block... how far it's already been bored, whether it has any of the notorious QC problems of the 70s, is it cracked or otherwise damaged, and so on.

Personally I will NEVER AGAIN build an engine with a 70s block, having struffled so nad all through the 70s and 80s with their shortcomings. Now that newer blocks that support cheap roller cams are available, and their QC is INFINITELY better, I would recommend that you sell that one to some "greater fool" that still believes in the "high nickel" myth, and get a new one. 96-2000 truck blocks are the best to get nowadays; there's MILLIONS of em in junkyards now, and they're just an all-around BETTER platform to build on.