408

4.030
4.00
-2cc pistons
gm mls head gaskets
317 heads 71-72
texas giant cam


i belive its like 11.5ish but i have no idea... just wondering if i would pick up some power with a smaller chamber and bigger valves...

car made 484/462 through an ls6 intake and ported 317's

great power but ya know we can always use more

 

Here ya go.

http://kb-silvolite.com/calc.php?action=comp

 

Do you know how far your pistons are in or out of the hole? With them out .005" and entering the chambers as 71cc, you're right about 11.1:1. That cam would love some more compression!

 

i dont know how far out of the hole they are they are off the shelf diamond pistons for the 408 just dont remember the part number....... and i figured it would love more compression... how much would i need to mill these to get them in a good range or should i just get a set of like stage 2.5 ls6 heads?

 

Use the compression ratio calculator at Ross Pistons' website, it's near the top of the page:
http://www.rosspistons.com/products/formulas.php#
It's the most accurate I've found and easy to use.

 

11.34 if your .010 out with a 4.080 bore HG .051 thick, 11.29 if its .008, 11.21 if its .005


with a 70cc head

Was it decked ?

 

Do you remember if the block was decked or not? That could help us find out if the piston is out of the hole or not.

Check you piston to valve clearance before you shave your heads.

 

it was a stock 6.0 lq4 block.. just had it bored... so i dont belive it was decked at all..

and its using a stock gm mls 6.0 head gasket..

 

Set Deck w/ customer pistons and surface to correct for required quench

This is a step in the process of building an engine.

 

ok well i dont know if it was decked or not... atleast i dont belive i was charged for it... i had it buily by a local shop called E.T. automotive in garland texas.... i guess i will have to call and see if they still have the paper on my build