I currently have an 06 sierra with a 5.3l . I have since purchased a brian tooley racing cam package stage 3 truck cam with 218/224 110 cam and have decided to slap on sone 799 heads i had laying around. I want to restore my compression ratio due to the 64 cc heads im putting on. How much should i have them milled to achieve a 10:1 compression ratio.

 

Milling .007” will remove 1cc

correct me me if I’m wrong but that’s what I remember

 

Accurate.

However, I'd give the 706s a chance first.

 

Agreed! My 862 heads milled .032” made my truck nice and crisp... there is a write up online a 5.3 vs all stock heads

“Modified 5.3L Head Test: 706 vs. 799
This is the test everyone wanted to see, and the one every LS owner will be talking about. The 799 heads offered the most flow, bettering the 706 heads by as much as 20 cfm at some lift points. The chamber volume on the 799 heads was within 2.5 cc’s of the 706 heads, but the dyno indicated this did not translate into power on our test engine. The peak numbers were certainly close (473 hp vs. 471 hp), but the graph tells the story best. The 706 heads were simply better than the 799 heads through most of the curve. Would this change with the presence of boost? We think it might, but only at extreme levels that might tax the flow limit of the 706 heads.”

http://www.superchevy.com/how-to/eng...nder-head-test

 

Exact reason I gambled with pulling my CNC 317s off in favor of lightly milled 706s.

On a 370 with a ls3 gasket, this equates to about 12.0:1 compression.

I had to back off WOT timing to about 22-23 degrees. I run my AFR a little fat to be safe.