Whats my CR gonna be (its a LQ4) how bout if I shave them .20, .30, or .35?? Im gonna try to go with some LS1 valves, this should help the low flowing 5.3 heads right? Any info appreciated.

 

There used to be an excellent sticky on LS1Tech for this ( head volume vs CC, Internal Engine section ). Maybe one of the mods can track it down as I could not find it anymore.
As I remember, every 0.005" of thickness change makes volume change by 1cc. Every 1cc change is ABOUT 0.1 change for CR. Using that as a guideline, going from 72cc to 62cc with the heads should net a +1.0 CR change. Shaving 0.020" would gain 0.4 points of CR.
IMHO the "D" shape ports and bigger valves in the 6.0L heads are gonna be a plus over a set of stock 4.8/5.3 models. The smaller truck heads are used as good starting points for aftermarket performance folks as it is easier to remove material on a CNC machine vs adding and cutting the bigger domes on the 6.0L models.

 

I think your lose perfomance if anything. Your better off with working the 317 heads IMO.

 

if you want same flow but more CR go LS6 head, i did thta swap and now 11.1 but i do plan on going like .020 over winter to get me close to 11.5

 

nothing like having a 4.0 bore and a chamber made for a 3.7 bore

if your just wanting some compression just pull the 317 and deck them

 

and what did i tell you the other day when we talked you owe me $5 i will be down tonite to collect

 

for the effort and cost you can have bare 243 for less and get more CR out of them

 

Go for the LS6 243 heads.

 

now are you sure htey are ls6, LS4,LS2 243s?

they used the castings on many rides now, only difference are the valves same size but different weights

 

243s are LS6 heads.

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