I have some 5.3 heads just sitting here, and am going to be porting and polishing them, and have the chance to pick up some stock ls1 valves for 25 bucks or so. I know I would need new seats put in, but is it worth it to up the size of the 5.3 valves in the head to 2" and 1.55", or is there more involved? Is the valve the same length as the 5.3 valve, and same stem diameter? or would new guides have to be machined in as well?

How about valve springs for these heads, will a set of comp or crane valve springs drop right in like a normal ls1 head, or are the 5.3's any different?

Any help, or to just point me in the right direction would be great!!!!!

 

Any LS1 valvetrain fits the 5.3 pretty much. You can go as big as 2.02/1.60 without changing the seats, all you have to do is have them recut for what ever valve diameter.

 

Bo you've got a PM!