Which would be better on my 5.3? I know that if I go with the 5.7 or bigger they will have to be shaved, is it worth the extra trouble.

 

go w/ the 5.7's. i hear they flow about the same un worked, and have bigger sized chambers. fairly cheap too

 

unworked you mean not shaved??

 

i meant like flow tested, port and polished. i saw where the 5.3's flow a hair bit better than the 5.7's.

oh yea, how come the 5.7's would have to be shaved to set on a 5.3?
i always heard of the fbody guys just swapping out to 5.3's, didn't figure there would be problems the other way around. ??

 

The 5.3s have smaller combustion chamber design, and the intake and exhuast ports are a little better setup for flow, but they only offer better flow when enlargening the intake and exhaust ports to accomidate larger valves. It raises the compression ratio on the fbody and corvettes by half a point. It is the cheapest way to get what a p&p sets of heads would cost you. $800 to $1100 done with the 5.3 heads, or starting at $1500 for 5.7 heads.

Yeah, the 5.7s flow pretty damn well with a cam, and you just have to shave them a bit to get the compression back since the chambers are larger, but if you don't run a cam the larger 2.0 and 1.6 valves will not help out the truck much, and will still require a computer tune to get it to run the best, since it will change all the flow characteristics!