Start by looking on the other side of the block for the casting date. It will be 3 or 4 raised (not stamped) characters. The first character is the month ( A Jan, B Feb, C Mar ... ), last digit is the last digit of the year and the middle digit or two is date of the month. Similar date codes are on the head and both manifolds.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
As long as you are at it, get the casting number from the same side of the block as the casting date. It will be 7 digits long. Decode here.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
2193980 is a 1952 to 54 302 engine block. I don't know what that other set of numbers is.
The casting dates on the two GMC engines I have are below and to the rear of the second freeze plug from the front on the driver's side of the engine. Mine have a small round raised area on either end of the number with a line in it to make it look like a screw head.
Last edited by Bill Hanlon; 03/21/20269:16 PM.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Thanks for the info, so it seems the casting numbers reveal that both these engines are 52-54 , The pistons have been replaced , and they are the flat top design with a .990” pin diameter. So when I order new pistons I can supply these specs.
Here is an example of a GMC casting date. This one is from the head on my 228, but looks similar to those you would find on your 302 GMC heads and blocks. You can see the "screw head" at the right end of the date code. F162 decodes as June 16, 1952. '52 because this manifold wasn't made in '42
Last edited by Bill Hanlon; 03/21/20269:37 PM.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
