heads use for a 5.3
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heads use for a 5.3 new here and this is my first post. i have a 5.3 im building and doing the usual ls6 cam(01) and other little things. but i have a set of ls1 heads sitting around and wondering if i should put those on? my theory is it will drop the compression which is better for boost. the combustion chamber volume for ls1 heads is 66.67 while the 5.3 head is 61.15, so that would allow for more boost as well plus the intake valve is bigger on the ls1 head, so does this sound like a good reason to try it out or just stick with the stock heads knowing they are already proven good for boost?
You can use 317's on the 5.3's but it does drop the comp. ratio down a lot. Some guys have done it and complained about the car being very sluggish out of boost. I am thinking it will be about 9.5:1 comp. ratio with some 241's, LS9 gasket and an aluminum block 5.3. I have yet to assemble it. I am waiting to get a cam and some new lifters first.
doggy i hear a lot of this over here on how the car feels doggy out of boost. i come from the Buick world and i would say i am use to a car being real soft out of boost. one thing i done with my buick was run a thinner head gasket to bump the compression up a half point. the car felt much better out of boost but with 6 holes it wasn't much of a jump in power. i have a 5.3 i am going to use 317's on..going to try and get the compression around 9 to 1 by milling the heads..bought a 5.3 turned out to be 4.8..bought a rotating 5.3 assembly now to make it a 5.3 
wish i could use the 4.8 flat tops on the 5.3 rods but the 5.3 rods are suppose to be floating..not sure if the 05 4.8 i have has floating rods....hth somebody
Bob
wish i could use the 4.8 flat tops on the 5.3 rods but the 5.3 rods are suppose to be floating..not sure if the 05 4.8 i have has floating rods....hth somebody Bob Trending Topics
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Staging Lane
Joined: Jul 2006
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From: F22 Secret Lair (aka) The "Austin Millbarge"
The 317's will drop CR by about a point, but there are a few 5.3 motors with varying CR's. Some Gen IV's with flex fuel and active management have 9.9:1 and flat top pistons, which could be confused with the 4.8's.
