I started looking on craigslist for some 243 heads and found a set. guy is asking 450 for em. im gonna see if i can jew him down to 300-350. once i get a set ill prolly have them ported and polished.

 

You'll want to mill them .027 -.030 to maintain your compression ratio; they have bigger combustion chambers than the stock 5.3 heads.

 

im assuming if porting is removing material than milling is adding material? if i didnt mill them would it adversely affect anything?

 

No, a mill is a machine like a lathe. The acting of using it is called milling....also may be from the fact that material is removed in "mils" or 0.0001 increments.

In a mill, the part stays still and the cutter bit rotates. In a lathe, the cutter bit stays still and the part rotates.

 

gotcha. so milling a head decreases compression ratio and porting a head increases, am i understanding this right?

 

Milling I beleive would increase compression. Porting refers to removing material from the ports, around the guides, etc.

 

going to try and break 300 in this thing to day.

 

Milling increases compression. Essentially, you're taking a knife and shaving the entire mating surface of the head, with each pass, you're taking a little material. As you do this, it makes the combustion chambers smaller, therefor increasing compression.

 

Gotcha. Is ur truck 2 or 4wd?

 

good thing i seen this im getting ready to put a maggie 112 on my 06 ss and want to have it tuned in person. not going to use justune for sure. Area 47??? want to tackle it in the furture?