I want to lower the compression on my Big Block from 10.5 : 1, not looking to get to a specific number I just want to be able to run pump gas.


Here is what I have:
Engine: 446 Stroker - .030 bored 400 block – 440 Crank – Alum Childs & Albert Pistons running 10.5 Compression - 906 Heads


Heads have not been milled and block has not been decked.


In a related post I asked this question along with a Camshaft issue but want to start a new thread on this topic, I do appreciate all the good information on the last post.


I have been told I could run Head Shims and or Thicker Head gaskets.


How much will the .020 head shims lower the compression?


Then how much with the addition of the thicker gaskets? (.051-.059)


Also machining of the Pistons is an option, I have attached a picture of my Pistons.


I can face them down that is not a problem, plus it’s won’t cost anything.


Just don’t know how much to face off, any good rule of thumb?


Thanks

 

You are prob at more thah 10.5 to 1 C/R. Need the deck height, piston dome volume, head gsk thickness, head cc (prob about 88 cc on a 906 head) . I have a similar build and am at 12.5 to 1 C/R

 

Send this info, and then actual C/R can be determined.