I have a bone stock 5.3 silverado im gonna put a cam and heads on it. I dont know how big of a cam i can put on it with out change the stock torque convertor i want it to have a rough idle and get some horsepower and I have heads of a 04 gto with springs for a cam already in it. My questions are need to know if i need to change the rockers that are on it they are stock or if its even good to change to the 5.7 heads and want to know how big of a cam and what kind is good but cheap wise?

 

Try the search button up top. It has helped me out alot. Look at the specs of your stock heads, the GTO heads, which should be 243's. Look at what your wanting to use you truck for, and then you can ask a lil more specific questions, and I'm sure you will receive much more help and opinions. If it were me: I would get a TR220 cam, have the heads P&P, 5 angle valve job, and milled .30 to raise your compression. That would prove to be a reliable and peppy setup. Just my .02 though!

 

If you want it to have a rough idle, you're going to need a cam with a lot of overlap which will have a higher power curve and require a higher stalled torque converter to perform efficiently. Since you're keeping the factory verter, you're going to need a milder cam or it will be a dog down low...best bet is to just set the idle very low for that "big cam effect".

 

another idea is to call a guy that does porting and polishing on these heads. They will have the most accurate info on what your proposed combo will do to compression and how to make it work for you.

04 GTO was a 5.7 if I am not mistaken, which means you will more than likely raise you compression ratio without milling the heads. That will be good for HP, bad for mileage.

You don't have to change the rocker arms, but its not a bad idea for more power/reliability.

As for the cam and a stock converter, stay at or below 220 duration and you should keep a decent amount of TQ. The higher the duration is, the greater the overlap and power potential, but this also causes you to have the change the converter to make use of it. Its not easy or practical to have that "big cam chop" on a relatively small cam.

If its the sound you want, throw some cutouts in there and pull a plug wire. Thats the cheapest way.

 

Get harland sharp to rebuild your stockers they will be better than new for less than 300 bucks. Get a 218/218 or 220r grind for the stock verter on a 112 lsa for that choppy idle you want.

 

No, if he uses the GTO's 243 cylinder heads on a non H.O. 5.3 he will be dropping his compression ratio because the combustion chamber volume is higher. Lowering the compression ratio would be good if he was looking at going to a high boost turbo setup later on, but would also reduce power as well as fuel mileage. I don't know how you think raising compression ratio would cause reduced fuel mileage, you might want to read up on the relationship of compression ratio, torque output, ignition timing, and octane requirement. Any time you can raise compression ratio (to a certain extent) you will be gaining power and mileage, as the engine is creating more power per combustion event. Lower throttle input required to accelerate to and maintain a set speed. If he wanted to maintain the stock compression ratio while adding the 243 heads he would need to mill the heads to reduce combustion chamber volume, or if he wanted to bump up to 9.9 to 1 compression ratio, he could run the 5.3 H.O. (essentially the 4.8) flat top pistons.

 

If your rocker arm needle bearings are going out, or gone, take a look at Comp Cams trunion bearing upgrade kit. I've seen it advertised for $130.00, which would be alot cheaper than Harland Sharp's conversion. Be mind-full of the lift of the cam that you intend to run, as tests have shown over .570 on the stockers increase the side loading that the valve stem imparts on the valve guide and will accelerate valve guide wear. This is caused by the increase in wiping angle of the valve stem pad relative to the valve stem.

 

if you want lope, just get a TR220 on a 112 LSA and stick with stock heads but swap out the springs. but expect to not have an increase in power until 3000-3200rpm

 

You are absolutely correct, i don't need to tell you that. I was going more on the actual mileage (he will be putting his foot in it more and running higher in the band, hence mileage will probably go down). As for physics, I won't argue with what you said.

 

I do agree with you, more power = more mashing of the loud pedal .