FL Junkie

iTrader: (23)

ive searched and saw where people talk about getting the 5.3 706 heads. ive thought about getting some and doing some work on them. you can get them used pretty cheap. im still on the stock 241s. cam is the tsp 233/239. all else basically just full boltons and headers.
my question is on my current setup can i benefit from the smaller combustion chamber? that cam is a bit of a turd down low, being its an insane top-end cam. i was hoping the raised compression would give me some extra torque(and horses). or if had them milled it would bring the compression up some more.

can i get some advice? im not an expert on heads...this is just info from what ive read...

FL Junkie

iTrader: (23)

anybody?

NemeSS

iTrader: (127)

unported 5.3 heads are useless on a 346+ci engine.
the raise in scr is not worth the labor of installing these heads.
they are very well suited for a 5.3 or 4.8, but thats it, unless the have been extensively ported with larger valves and such.
if any thing, u might as well go with stock milled uported 243 or 799 heads, same as ls2. they will raise your scr and flow more than ls1 heads as is.

FL Junkie

iTrader: (23)

can you explain why? if it raises scr up doesnt that raise power?

my heads have 66.67cc chambers. ls6 heads have 64.43cc. and the 706 heads have 61.15cc chambers. if the 706s flow identical to the 241s how would it be different? the ls6 heads also only flow slightly better...

NemeSS

iTrader: (127)

the 241 come equipped with 2.00 intake valves and the 706 come with 1.89 intake, if the 5.3 heads are upgraded with 2.00 intake valves then, they in thoery should be superior over the 241. if they are supposed to flow the same. usually when the 706 get ported, the chamber is also matched for the bore being used on, since the 4.8/5.3 bore is 3.78.
proper application specific scr,dcr and corresponding camshaft valve events will equal the greast gains and throttle response. imo i would not throw some 5.3 heads just to raise the scr. or if i did i would just use the 243 or 799.

FL Junkie

iTrader: (23)

so to use those heads i would be looking at machine work either way. i know the valves are different. but 243s are much more costly in just used factory condition. 706s are much cheaper.
isnt it the same thing to put on 243s? your raising the scr plus a little better flow. i get what youre saying, i just dont see how getting some 243s is any different from 706s. granted they would need work, in theory it would work.

NemeSS

iTrader: (127)

if u upgrade the or perform the same mods to the 243 they will yield better gains over the 5.3. the ls2 arent really that much more and hold way better value than 5.3's.
this may not apply to your build, but ive had good success with 243 heads on my own car, they just use larger valves, and some light labor i performed in the runners and valve throat area. angle vj and backcut.
no real metal cutout, just whatever i needed to remove with 60grit rolls to get the desired measurements. didnt even grind down the rocker arm boss.
so far, so good, 490rw thru ls6 intake and 375ci.