Does anybody know what 340 piston this is? I took it out of my -68 340. Actually cast year -67. There are some numbers inside the piston, B284R and they are .030 over. Thanks! -niklas
The '68-'70 340s were rated at 10.5:1 ratio by the factory but were actually around 9.5:1 due to large open chamber heads. Compression wise you should be fine esp if you run a hotter than stock cam.