ok i bought a lm4 = aluminum 5.3... bored it out to 3.905 and put ls6 heads on with a ms3 cam. my compression is low(compression test) so i was wondering if i need to mill the blocks deck ??? any ideas would be great thanx

 

any suggestions

 

....um.... I thought that the LM4 aluminum 5.3l engines could only be bored a max of .010.

I know that the iron 5.3l engines can safely be bored to 3.905 but some still recommend getting the block sonic tested for that.

I hope I am wrong for your sake!

 

I have a book that said the cylinder liner is an LS1 99 mm liner just not bored out to the ls1 size.

It does look pretty thick on my lm4....

 

hmmm...
makes sense, sort of
id be weary, i dont think the lm4 5.3 aluminum block was designed to
be bored to a ls1 bore size but i may be wrong