I got a great deal on another 5.3 short block and a set of allu 6.0 heads. My plan is to **** can the factory pistons and throw in some JE flat tops. How much do i need to mill the heads to get it to 10 to 1 comp? I am just gonna set it with a.r.ps all through it and let it go at that? I wanted to bigger motor but i dont think i will let this deal pass me up. I called MTI about it and they were not sure. Thanks in advance

 

wow a professinal shop like mti wasn't sure that is scary they probaly want you to bring them the motor and then they'll charge you out the *** to build it then they'll tell you how much they milled it lol isn't that how it works?

marc <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

 

well, what is the stock truck compression ratio? i can't remember off the top of my head at 1 A.M. well, the stock compression ratio is with the stock "dished" pistons, if you put in flat tops it will raise the compression some, i'm not sure how much, but i will find out.

Matt

 

Stock 5.3 compression is 9.5:1.
A 5.3 short block with 6L heads gives you an 8.6:1 CR.

My opinion:
If you are going to replace the pistons, go ahead and have the block bored. If you bore it out to 3.9 or 3.905, you can use LS1 sized pistons. It will be very easy to find these pistons off the shelf, so they will be cheaper. This will basically give you a 5.7 Liter iron block. Use the 5.3 crank. Your choice on the rods. This will also lessen the bore difference from using 6L heads on a 5.3 motor.

With flat top pistons and unmilled 6 liter heads, your CR will be 9.65:1. Rough calculations show that milling the heads .030 will give you a 10.15:1 CR. You should be OK with stock length pushrods if you are using a decent sized cam.