Im looking for opinions on an acceptable compression for a new 427 build (4.125x4.00) I keep reading about being able to use more timing and or compression with the aftermarket 12* heads. I dont want to go too far on the compression but dont want to miss out by not having enough. I get that the DCR is where its at ,but I feel I have to shoot for a static compression ratio when ordering pistons.


TSP short Block (Re-sleeved aluminum block)
TFS 255 heads (69cc combustion chamber)
Cam will be a Cam Motion LLSR (no specs yet)
Callies/Wiseco rotating assembly (-4cc flat tops, 6.125" rods)
.041 Cometic Head gasket (4.140 bore)

Compression Calculator spits out 11.667 for this combo

This will be in a 67 Camaro (Weekend hotrod)
T56, 373 gears, 26" tires
Holley Terminator EFI with computer controlled timing
Victor Jr single plane intake

91 Octane fuel


Thanks!

 

Darth will be along shortly to help out...nice build btw.

 

With a properly spec'ed cam, I don't see an issue with that SCR at all.

But that's just me.

KW

 

I'm surprised thats the comment. But he did say "properly spec'ed cam" too. Whatever Darth says, I'd run with. No offense to KW Baraka

 

What is the defined hp goal and rpm limit? Gotta start here first. With bore and stroke define, you can figure out head requirements and cam specs. With 91 fuel and cam spec'd, you can then figure SCR based on DCR limit of fuel. Hope this makes sense.

 

You're going to need to iron out your camshaft before you decide on a set of pistons, but mid 11's on your static is about right for most of the street cams guys are running. If you're looking for a real aggressive camshaft, I'd be shooting for closer to 12:1. But, it all depends upon what you want out of the engine. You're going to need some camshaft to feed 7 liters, though.