13:1 Compression Pistons in 340 Small Block

Roger that..... mild street build, pump fuel, and 12:1 or 13:1 static CR don't go together. You are right OP, these pistons would typically be usable only with certain large cams and fuels.

If you use them with too small of a cam on pump fuel, then the engine will experience what is called detonation, which will destroy things in short order... unless you use the different fuels being suggested. If you put in a big cam to prevent that, then low RPM performance, and what is termed driveability, goes into the toilet.

Help us all (and yourself) by explaining better what you want to do with this engine/car. 'big block buster' is a bit ambiguous, and you can do that with a highly modified /6 and a lightweight early A body! Do you want to run pump fuel? Is economy important to you? Drag race only? Or are good street drivability and good cruising manners the most important things? Auto trans or manual? Picking parts all starts with the application....

And welcome to the site! This is pretty knowledgeable group.

Thanks for the feed back!

I would definitely like to be able to drive this on the street but also have something I’m not scared to talk down the the strip and roast the tires with. This engine is going into a 340 Dart but the block is non numbers matching (if I was numbers matching I would rebuild it to stick specs) I’m not scared to spend some cash on cams and run Some high octane fuel and I don’t care for fuel economy but I’d like to get better then 8mpg. It’s an automatic car and I haven’t looked into torque converters or anything along those lines. I have a 727 trans I was going to use with this application if that helps at all.