360 .... Looking for 9.5 - 9.8 Compression ratio

[Darthemi75]

I have 360(Std bore) with KB hype .flat top pistons, and i looking to make 9.5-9.8 compression ratio with my J Heads # 3418915(millodon 2.02-1.60).

My question is:

How much chamber CC including my gasket do i need?.... to make 9.5-9.8 compression ratio????

 

[70aarcuda]

how far down are the pistons in the bore?

 

[rumblefish360]

If you are at a zero deck height with the pistons, then a .039 thick gasket can be used. Minimal bore size on the gasket helps.

 

[Darthemi75]

i have kb107 std pistons.....i only want to know how much cc chamber i need to make 9.5-9.8 compression ratio....

 

[rumblefish360]

Cylinderhead cc's? Oh crap, sorry.

72cc

 

[JoeDust451]

I have 360(Std bore) with KB hype .flat top pistons, and i looking to make 9.5-9.8 compression ratio with my J Heads # 3418915(millodon 2.02-1.60).

My question is:

How much chamber CC including my gasket do i need?.... to make 9.5-9.8 compression ratio????

Kind of a loaded question, do you want 9.5.1 or 9.8.1?? I believe you'll be right around these #s with the basically stock 915 J CC head (around 76cc) & a .039" gasket with the KB107s.

 

[Jo Diesel]

I have that exact set up in my 360 and it made about 9 to 1. Planning to add a Paxton that I am rebuilding so I am leaving the compression alone.

 

[dgc333]

i have kb107 std pistons.....i only want to know how much cc chamber i need to make 9.5-9.8 compression ratio....

You need to know how far the pistons are down in the cyclinder at TDC and the volume of the heads you are using before you can calculate what you need in the way of chamber cc's to get to your compression goal.

For example: Assuming the block is at a nominal 9.600" then the KB107 pistons will be 0.012" in the hole. Assuming the your J heads have a typical 72cc volume. This will give you 9.36:1 compression with atypical 0.039 thick by 4.150 bore head gasket. Reducing the head gasket to 0.028" thick and you will have a 9.60:1 compression.

But you need to measure the head volume and measure the piston depth in the cylinder because most blocks are taller than the 9.6" nominal and the heads could be less or more.