spilt my milk and hit reply to quick...anyways, i've considered holding off for a while on my 6.0 swap(couple more months) and buying a set of 5.3 heads and having 2.00/1.55 valves with a 3 angle valve job and mild porting with 02 LS6 springs and retainers on my motor to hold over. and then going with patriot performance 6.0 heads with some milling for later on the 370

 

I thought the 4.8/5.3 heads were better, I'll be damned. The power differences I am talking about is going to be minimal but if you are looking for all out power you are set.

 

the only thing about the 5.3 head that is better than a 5.7 head is the smaller combustion chamber. they don't flow as well because of the smaller intake valve. if you want all out power why not spend the extra 30 bucks and go with 2.00" valves?

 

Well if it is $30 then go for it, but don't expect huge gains by the larger ones.

 

not huge...but every bit helps if you're looking for optimum performance and efficiency

 

What is milling and decking? Would it cost a whole lot? What would be the performance gains as far as hp/tq? Thanks Guys!

 

milling/decking are the same thing i believe...it is cutting the bottom of the cylinder head down to make a smaller combustion chamber, inturn raising your compression ratio.

 

Milling is cutting down the head, to decreese the cup area of the head, which reduces the combustion chamber size, which in turn increases the compression ratio of the motor. It is good to get a set of 6.0 heads, then just mill them down to the stock 5.3 head spot, this way you get slightly larger runner on the intake and slightly larger exhaust ports, that use the same headers and intake manifold as the 5.3, and keep the compression ratio the same. You get larger valves and the capability of a higher lift from your cam without having to do any other work to your heads. The LS6 head has not better spring setup, but has it setup for larger levels of lift!

Decking, is specific to the block, making sure that the level or surface of the block itself is perfectly even and flat. This should be done on any rebuild regardless, don't worry, you should not be worried about this with head work unless you have a large amount of mileage on the vehicle.

 

I had the heads done on my 5.3 by a guy that's been racing and building motors for the past 15 years. I've seen the car he built run 5.60s in the 1/8th. When he talks I pay attention. He says the porting does the trick and the polishing is just eye candy. Kept the stock valves with a 3 angle valve job and 918 springs. Dynoed the truck before and after. It made 26 hp on motor but it felt more like 50 the first time I drove it. It made 36 more hp on the same shot of juice and I dropped 3 tenths in the 1/8th.

 

Sweet, was that using the stock cam?! If so, I will probably spend a week and pull my heads off to get them worked on, well in maybe 2 to 3 months when I can afford it.