stock pistons in 348 truck engine

[68-biscayne]

New guy here reporting......

Big reader of the 348-409 forum. I have a 655 block 348. Are the pistons in this engine the same as the car engines, and the difference in compression ratio achieved by the "eyebrows" in the 655 blocks' cylinders? Car at 9 1/2 to one and truck at 8 to one? Or are the pistons different car vs truck?

Thanks!!
Kentt

 

[larry t]

New guy here reporting......

Big reader of the 348-409 forum. I have a 655 block 348. Are the pistons in this engine the same as the car engines, and the difference in compression ratio achieved by the "eyebrows" in the 655 blocks' cylinders? Car at 9 1/2 to one and truck at 8 to one? Or are the pistons different car vs truck?

Thanks!!
Kentt

Truck and car pistons are different. I've read (never really cc'd a block to see) that the eyebrows in a truck block drop the compression from 1/2-3/4 point with car pistons. Anyone have a solid number on this?
Larry T

 

[jim_ss409]

Yeah, the truck engine has both a relief in the block and a combustion chamber in the head. The truck engines had really low compression, something like 7.75 to 1 I'd guess that the truck pistons might be about 8.5 to 1 in a car block with car heads, but that's just a guess. Maybe someone knows for sure, or has a better guess.