You will have to measure your piston to deck height with the heads off the engine and a good prepped and clean deck surface. Your pistons could be anywhere from .004 to .015 out of the hole (factory tolerances). From there once you determine how far your pistons are out of the hole, you can select your head gaskets.

 

Thanks for all of your input you guys have been really helpful. Next question... would it be best to just sell the Z06 cam and get one closer to what im lookin for or will this cam still provide good power with the current set up?

 

I think that cam will do well in your 5.3L. Who can complain with power from idle-red line and silky smooth operation without the need of any other modification, short of a given tune.

 

I think the Z06 cam is a good cam if you want a stock like truck with better power and stock like drivabilty. I will likely put one in my wife's truck when I get to that point. If you are trying to build a barn burner then there are better cams out there that you could run. I would seriously think about what you want from your truck, given that you are swaping heads I am guessing you might want more from this swap than the Z06 cam can provide. Just a thought and my .02

 

you will see on the boards that everyone has a different opinion about things, so just research things as good as you can and do what you want!! now on to the info again. you need to get back down to the 61cc chamber or whatever cylinder volum it was weather that means milling or thinner gasket otherwise your going to loose power. the ZO6 cam is a good cam from what ive seen on here. you can always sell it so just try it if you want to. another .015 milled off the heads with the stock gasket would net you .020 mill and should get you back to the right compression

 

Yeah, I think with what I am looking for right now, the set up will do. But I do believe that I am goin to have another .025 taken off the heads, and maybe that will be what I am looking for for now. If nothin else I can always have my stock heads put back on for a boosted application. Thanks to all for your .02.

 

Check with your machine shop to figure out exactly how much to mill off the heads. There are no constants with milling. Keep in mind you're not milling a perfect cylinder that does not change shape. Instead you're milling a domed combustion chamber with many curves and irregularities. You'll start milling .010" to begin with and remove 7cc of chamber volume the first time, the next .010" you could only be taking 4cc off, third time you're only taking 2.5cc off, ect ect. Follow me? I pulled those numbers out of my *** but I hope it gets the point across. Bottom line have your machine shop double check the combustion chamber volume before and especially after milling. Just bring him your stock specs of the 5.3L and say the stock heads have 61.15cc of volume so with a target compression ratio in mind he should be able to hit that target (10.1:1 for example) by calculating the after-volume of the heads.

The stock '03 5.3L has 9.5:1 compression, so if everything including the head gasket remains the same, you'll want to see if you can get the 243 heads down to 56cc's with 10.09:1 compression and perhaps a max of 53cc's for 10.48:1 compression on low-to-mid octane pump gas. The '02 LS6 cam found in the Z06 is well known for bleeding off high compression due to the longer duration at low-rpm but pumps up the high rpm horsepower considerably. I would not hesitate to run anywhere between 10 and 10.5:1 compression. Don't forget about the tune afterwards though to give the engine the appropriate fuel ratio, spark advance and tranny line pressure to handle the newfound power.

That is the camshaft you have at this point, right? The '02+ LS6 cam is a 204/218, .555/.551 lift on a 117.5 LSA. With those 243 heads milled down for higher compression you are probably going to experience no loss in low end torque down low with greatly improved throttle response from the higher compression, while also feeling an explosive gain after 3500rpm's with an improvement of about 25lb-ft of torque, but over 50hp! Get the tune spot on and you'll have a 340hp, 350lb-ft of torque 5.3L on your hands.

 

Sell those 243 heads and go with a set of ported 5.3L castings. They'll work correctly on the smaller bore and you can probably come out even money wise. Search on ls1tech for more info.

PS- I've noticed that, in general, people are like rolling a 55 gallon drum down a hill, the empty ones always make the most noise...

 

I think im gonna stick with the heads seeing as I already have them ported and polished and springs installed. I began the tear down tonight. So hopefully I will have it running by Monday.

 

The cam I have is 204/218, .550/.550, 117.5 LSA, but yeah close enough. I am hoping that after the tune it will be fairly peppy since it hasnt even been tuned yet. The only thing I had on it before was a handheld.