I have searched and read a few threads on guys milling heads on 5.3 motors lately........not a whole lot of "I run this" answers were out there on the subject. With all of the NNBS trucks running higher compression, I figured milling stock 706 heads to bring the compression up would get more popular as a cheap way to increase compression. If we had one place to talk about it

Does anyone run a set of milled heads on your 5.3? If you do.....

How much are they milled, and what thickness gasket are you using?

Did you have ANY issues with your stock or NNBS intake manifold fitting?

How what are the specs of the cam that you run, or HAVE run?

What pushrod length do you run?

Do you run a stock size truck intake valve or a larger one?

 

Mines .035 milled - intake feels tight setting in there, running stock thickness gaskets

I was told max was .042 for intake- that was back in 08

 

I'm thinking of doing the same thing. I'm going to build a set of 862s for my 04 5.3L that has the cracktec 706 heads. I want to mill them to bump compression to about 10:1 and swap in a cam with about 200* of duration. Basically that's a clone of a L33 setup, but with dished pistons.

I'm more used to Pontiacs, where milling .030 would reduce chamber volume by about 6CCs. It's possible to cut the 72-newer heads massive amounts, like .040-.060" or more to boost compression when using smog-era heads. Then we simply cut the intake or the head's intake face a matching amount and slot the bolt holes in the intake so the bolts line up.

I'm new to these LS motors, so I'm not sure what you do with this plastic intake. I guess you could cut the head's intake face, but not sure how much you can cut and still get the bolts to line up and the O-rings to seal.

Another thing is the head gasket selection. Not sure how cutting these heads affects gasket selection and quench distance? I'm used to building motors where .040" quench is ideal, and head gasket thickness could be tweaked to affect that. It would be possible to mill the heads a lesser amount and use a thinner gasket to achieve the same compression, depending on what is available.

 

Im curious myself because ive personally never had heads cut on anything of mine and my tahoe has 706 heads I wanted to go with a .052 shave never persued it because id like to wait till they leak or something so im not just doing it for the sake of doing it and its my daily driver lol the 706 head has the smallest cc head of all the vortecs someone correct me if im wrong there. But im not sure how much you would notice for power gains buy doing that .that another reason I didnt do it its the work to pull them+the cost of milling and gaskets+headbolts ect. Worth it.?

 

Not 706 but i had my old 317s milled .045. Intake fit. But in order tp bolt on the power steering pump/ alternator bracket to the head I had to put the bolt in first then bolt down the head.

 

Mines .035 milled - intake feels tight setting in there, running stock thickness gaskets

I was told max was .042 for intake- that was back in 08
Sorry to dig up an old thread but did you have any PTV issues and what cam and pushrod length did you use, thanks

 

no, I'm running a low lift cam - tr220 (.551/.551)
for the push rods I don't remember what length it's been so long maybe 7.4 (which I would think now is wrong, didn't think back then about it)

 

I am wanting to shave my 706 heads 45. and I have seen her head gaskets which are 40 a stock head gasket is 54 so I'm gaining 14 by the head gasket but my concern is I'm going to run a stage 3 low lift Texas speed cam but I do not want to be over 11 and 1/2 compression this is the best because I don't want to run race fuel I'm running a 2002 5.3 LS as a street truck going drive it and rac does anybody know anything about that combination if it will work and what I will have to do

 

But by reading on here I feel like 42 is the smallest I can take my 706 heads but I'm not sure if I can still run my thinner head gaskets they are 40 and the stock are 54 does anyone know how much that would raise the compression it's a lm7 5.3 2002 so it's not running flat tops

 

You're compression would be 10.5:1-10.7:1.