By the suffix code on the front passengers side head deck that will end in a code such as ATX. Or by the date code. Which will look something like this example: C 5 9
C = March 5, 5th of that month. 9 1969, or whenever years that block was casted. You can find the date code on the bellhousing on the rear of the block.

 

block# is 3970010 ...it says 302,327 and 350 ci how do i tell which one it is,guy told me 350.

Your guy's probably right.

If it's a 4-bolt, 99.9% of the time it's going to be a 350.

 

Also... It doesn't matter what it was to start with... the block is the same. What makes those three engines different is the stroke. If you're starting with a bare block, what makes it a 302, 327, or 350 is the crank you put in it.

First-year 302s (67, right guys?) used a smaller main journal size, but I doubt that's what you have since its an 010 casting.

 

3970010 Block casting number

With a 3970010 casting number and if it is a 4 bolt block it will be a 350 100% of the time. A 302 didn't use that block casting number and there were never any 4 bolt main 327s from the factory. Lots of people took forged large journal cranks from a 327 and a 4 bolt 350 block and "made" 4 bolt 327s. The 3970010 casting number was used on blocks from 1968 through 1992. The years are:

Cylinder Block Casting Numbers
Manufacturer Cyl Liter Model VIN CID Year Casting
3970010 GM 5.7 No Model 4 350 V 8 78-79
3970010 GM 5.7 No Model 6 350 V 8 80-88
3970010 GM 5.7 No Model 8 350 V 8 80-80
3970010 GM 5.7 No Model B 350 V 8 78-79
3970010 GM 5.7 No Model H 350 V 8 73-77
3970010 GM 5.7 No Model K 350 V 8 70-75
3970010 GM 5.7 No Model L 350 V 8 76
3970010 GM 5.7 No Model L 350 V 8 77-82
3970010 GM 5.7 No Model L 350 V 8 83-86
3970010 GM 5.7 No Model L 350 V 8 89-92
3970010 GM 5.7 No Model M 350 V 8 74
3970010 GM 5.7 No Model M 350 V 8 79-88
3970010 GM 5.7 No Model P 350 V 8 68-77
3970010 GM 5.7 No Model P 350 V 8 80-83
3970010 GM 5.7 No Model R 350 V 8 69-76
3970010 GM 5.7 No Model R 350 V 8 77-80
3970010 GM 5.7 No Model V 350 V 8 74-76
3970010 GM 5.7 No Model Y 350 V 8 68-75

From my AERA casting number book. I get new books every year as part of my membership in AERA. http://aera.org

 

First-year 302s (67, right guys?) used a smaller main journal size, but I doubt that's what you have since its an 010 casting.

That's correct, no 302. The first 302 was a 327 2 bolt block with a 283 crank in it. There were only 602 of them made. In 1968 they had their own special large journal casting.

The first 350s made in 1967 had something different about them too. The rod journal size was 2.000, the same as on the rest of the small journal engines. The large journal engines with a spin-on oil filter weren't until 1968 model year. (summer/fall of 1967)

It worked, thus it lasted for 50 years in different sizes and configurations.

Some of the casting numbers were used on small AND big block Chevys. Same casting number. One a small block (or even a 6 cylinder) and the other a big block. Yeah, casting numbers are fun time.

 

found more

found these on top of block under head....ko9 16 tx3.... now i'm really lost!

 

Engine Codes

found these on top of block under head....ko9 16 tx3.... now i'm really lost!

A 350cuin engine out of a pickup made in Canada and the engine work was done on Sept 16th of 1975.

K Where built:St. Catherines, Ontario (McKinnon Industries Canada)
09 September Month built
16 Day
TXB 1975 350 conv.cab L LS9 165 4 C-20 to 3500

What you think is a "3" is a "B" 99% chance it is a 4 bolt main because it is a 3/4 ton or 1 ton.

 

thanks

thanks for the help....