flynlow3

iTrader: (2)

To my understanding, 5.3 truck heads will bump up the compression on an ls1 motor. I am planning on working a set with my hot cam. I was told the intake valve is smaller but the exhaust valve is the same size as the ls1 heads. Is it a good idea to have a local shop take my intake valves from my ls1 and open up the 5.3's to make them work? I plan on using my rockers and lifters out of my ls1 heads in the 5.3's and possibly having this local guy port and polish the heads. There is nobody close that works on these style heads and this guy is an experienced guy just not with this set up. What do you guys think I should do. Im kinda on a budget with money and time. The motor is out and thats why I decided to do heads at this time and the cam.

Jeff

LS1Z28-00

iTrader: (8)

im currently putting in stage 2.5 5.3 heads, these bump my compression to 10.75 so im sure its the same for you but not 100%, as far as stock 5.3 head valve sizes i dont know, but if you are doing a cam it would probley be a good idea to put in bigger valves, my valves are 2.04/1.575, hope i helped some but 5.3 heads stock outflow ls1 heads and bump compression for a little more power, so it will be a definate upgrade, good luck

flynlow3

iTrader: (2)

Good deal! Thanks!

408z28

iTrader: (44)

If you have an experienced machine shop, thats all that matters. My machine shop had never bored, honed, balanced or did a valve job on an ls1 when I did my first 408 two years ago....and that motor made 496 rwhp when I finished it. An engine is an engine, and a set of heads are a set of heads. Just because its an LSx style engine doesnt mean you do anything different to it.

As for the valves... If Im not mistaken you can run a 2.04 intake valve on a 5.3 head. A 2.04 is plenty big enough for a stock cube/head & cam set up.

You can re-use your lifters, and rockers.

flynlow3

iTrader: (2)

I didnt realize the 5.3 stock heads out flowed the ls1 stock heads. Thats crazy! But Im happy!