I just pulled apart my 1970 455 motor.
Do these look like the stock pistons for this motor? Thanks in advance for any help.

 

Good possibility. Most aftermarket pistons have numbers in the top. Do you have the oil pan off ? look and see if there are numbers on the inside of the pistons.

That being said, the engine has obviously been worked on before. Those are not stock head gaskets and the block has been decked. Can you measure the bore size ?

 

The semi-circular notch and the soup bowl-sized dish in the piston show these to be factory cast low-compression pistons. Are you sure this is a 1970 short block? Checked the VIN derivative stamp?

 

^^^^^^^, agreed. IF it is a ‘70 block, it’s been in to, as mentioned.

 

 

The "9" shows this to be a 1969 model year block and the "X" shows this to be from the Fairfax, KS assembly plant, which only built full size cars in the 1969 model year. This short block is from a 1969 low compression 2bbl motor that was born in a Delta 88.

 

I have an exact version of this engine ('69 455 2bbl), and I know it's factory compression ratio rating was 9.0-1 with a OEM gasket. What was it's actual compression (I guessed 8.7, and that it's better slightly than an 8.5 rated later model)?
The reason to know is that this one is usable as is, but may need my ported #6 heads (and my one set of shim gaskets) with large valves (2.07/1.71) and bbo intake ports to allow it a small cam. 98% Street use and abuse only! (68 sports coupe, auto, 3.31 gears).

 

Thanks for all the answers guys. That’s just what I needed to know. Definitely appreciated.