First off, I own a 2007 Silverado classic. 5.3l. I was given a set of new ls6 heads, yes given. I am told they will bolt right up to my current engine. I figure that when I have it apart I should probably replace/upgrade some things. Looking for suggestions/recommendations to build a durable and more powerful engine. Don't plan on racing it or anything, just putting more power. Below I will post the heads specs. Any and all suggestions/comments welcome.

LS6 Cylinder Head Assembly
Fits any 1997'2008 LS Family engine*
2.00 hollow stem intake, and 1.55 sodium filled exhaust valves
.570 max valve lift
210cc 'cathedral port' intake ports
70cc D-shaped exhaust ports
65cc combustion chambers
Bare head P/N 12564825 available separately

Heads P/N 12564824, P/N 88958665 and P/N 88958622 are
assembled with the following components:
12565311 Intake Valves
10166344 Valve Spring Retainers
12565312 Exhaust Valves
12482063 Intake Valve Stem Seals
12586484 Valve Springs
12482062 Exhaust Valve Stem Seals
10166345 Valve Locks

 

U want to throw a cam on there?if so id run a 224/224/114lsa cam.. I ran this in my 5.3 with long tubes and corsa exhaust and intake i put down 380rwhp .. Ud probably see the same or more with the ls6 heads and a cam around this duration.. Especially in a truck

 

If you don't want to spend too much just get them milled 15-20 thou to bump compression and get a flat surface and use a 0.40 Cometic gaskets to tighten the quench. You should do a tune after switching heads.

 

Not 100% sure, but I thought that by 07 even 5.3s had the 799 heads (which are basically the same as the LS6 except with different valves). If that's the case, then these won't really do much for you unless you really need the light valves for 7000rpm+ shifts.

 

My 09 Silverado had 243 heads, just not the lightweight valves.

I would personally just disassemble, clean the head and valves and then lap the valves in each cylinder and re-clean to make sure there is no lapping compound left. Then I would replace the seals and the valve springs if they are the yellow ones. Just install the LS6 valve springs from GM. I believe the new ones are blue. I would also use GM seals, they fit and work well.

 

any way I can look that up to see?

 

Sure lol pop the good on your truck and looks for the casting numbers on the heads near the front and below the valve covers if you see the numbers 799 or 243 you already have the ls6 style heads only difference is they don't have the lightweight valves.... But you wouldn't notice the difference anyway

 

Look right on the head itself for a casting number.

 

I'd put a higher performance cam in it, and as far as cam specs that'll depend on how you intend to use the truck, and the rpm range you'd like to see the most hp/tq gains in, along if you're willing to put a higher stall TC in the A4 trans..

 

thanks fellas

 

Found it on my truck, they are 706 heads.

 

Is there a way he can know if he has the hollow valves ? Other than dis-assembling the head and weighing them [ 74.7 Intake and 64.6 exhaust ] ?
Were LS6 valves longer by 0.050 giving a installed height (from spring seat to bottom of retainer) of 1.850 instead of 1.8 ? If so, he could sell them to help fund his cam and header purchase.

 

Recommend long tubes if that hasn't already been done. Didn't see it mentioned