I have a 74 auto with what I thought had the original engine in there but now that I've cleaned up the engine block and pulled the numbers It looks like it's had an engine swap. Can anyone confirm that I've identified the engine correctly?

I think it's a LM1 from a 79.

Block numbers: V0410DUC
Below those: 19J290454

If that's right, any opinions on how that compares to the L48 I thought was in there and how it will perform with the carb and trans?
Carb: 77 Quadrajet 4 barrel (17057202)
Engine: LM1 (I think)
Trans: TH400

 

DUC is a passenger car block from '79 or '83 w/auto trans, police use, 170 hp. Probably not too shabby and similar to the '74's 195hp Corvette block. Assembled in Flint MI, April 10th. The 9J seems to indicate a '79 made in Jonesville WI; not sure what the 1 signifies.

 

The engine and carb decode seem to be right. There isn't any significant difference between what was originally there and what is there now. Same block, crank, pistons, cam. Both engines had smog heads. The carb might be a little bit less desirable as it is a truck calibration but it will run.

Do you have any plans for it?

 

The..."290454" part of the lower number is the serial VIN number of the car it was installed in. These would match the last 6 digits of your car's VIN if it was original to your car.

 

The first digit of all GM VIN's indicate the GM division. 1 is Chevrolet, 2 was Pontiac, 3 was Olds, 4 is Buick, 6 is Cadillac & 8 was Saturn.

 

I know that the first digit in a full VIN sequence is the division, but is that first digit of an engine stamp (abbreviated VIN) the same?

 

I'm working from memory here, but from what I remember, up to 68 the block VIN derivative started with a single digit for the year. I think for 68 & 69 the VIN derivative started with a "1", for 70 it started with a "7", for 71 it started with a "C", and then from 72 on the derivative started with a "1". This is off the top of my head, but I "think" that's how the block's VIN was configured over the years. This would be for Corvettes from St Louis. Other plants often stamped blocks differently, and didn't even always stamp the VIN in the same place as it is on Corvette engines.

From 72 on, when Chevrolet changed the VIN replacing the "9" for Corvette with a "Z", and adding the letter code for the engine, it appears the block VIN derivatives became pretty uniform. The block derivative became the same as the regular VIN, less the second, third, forth & fifth digits (the "Z "for Corvette, "37" or "67" for the body, and the letter for the engine).

I don't know what else the "1" in the block VIN derivative could stand for, except Chevrolet. I've seen Pontiac blocks with a VIN derivative starting with a "2", which is the GM VIN indicator for the Pontiac division.

This is how I recall and interpret the VIN derivatives, though I could be wrong, and an open to other suggestions.