71 C-10 motor questions

[Hennyhog]

Howdy,
Bought a 71 C-10 a few months ago and have been going through it changing out parts and addressing each and every issue as they come up. I have been trying to decipher through many of online sites the numbers off the block and haven't gotten to far. First off the VIN stamped on the block hasn't any letters (151175489) in it which is stumping me. Secondly I can figure out the first half or so of the Engine code (K 03 13 CMJ) K= ST. Catherines, OT and made on march 13th....have yet to figure out the CMJ part. These numbers were taken off the front of the motor, passenger side, below the head. This isn't the original motor and I'm fine with that....just want to know exactly what I'm working with/on. Any help or info from ya'll would be greatly appreciated!

Thanks,
Henny

[GASoline71]

The "CMJ" is the suffix code and it could either be a 1974 350 or a 1980 305. You need to get the casting number off of the back of the engine block. Located on the bell housing mount flange... drivers side.

Gary

[geezer#99]

Look here!
http://www.mortec.com/

Or here!
http://www.nastyz28.com/decode.php

[Hennyhog]

Thanks guys. I was on those sites and saw the CMJ was either a 74' 350 or an 80' 305. I will look on back of motor tonight to see if I can get more info. Still stumped on the motor VIN number though. Is there a website where you can enter the vehicle VIN number to find out info?

Thanks,
Henny

[GASoline71]

The VIN just matches the engine to a vehicle. I don't think you can get an engine size from it. But I could be wrong.

The only way to be 100% sure is to get the casting number off the back of the block. That will tell you if it's a 350 or a 305. Then the suffix code will let you know what application it was used in.

Gary

[67 chevelle]

you can take the valve cover off also and get the casting number from the middle of the head , that will tell you if its a 305 or 350

[Hennyhog]

Ok boys....casting number off back of block reads GM 3970010. I am getting anywhere from a 1969 302 cu out of a Z28 4 bolt main, to 1968 327 cu A, and 350 cu 2 or 4 bolt out of a 69-79 car, truck vette. Your thoughts?

[GASoline71]

I'll bet it's a 1974 350. As per the suffix code.

Gary

[Hennyhog]

My bet too Gary. Have to tell you it's pretty fun tracking numbers down. I had no idea Chevrolet put out a 302 cu. Next is my 3 speed tranny and figuring that out. Thanks again folks!