demonsmokr

I need help guys. This is my first full rebuild of an LS motor that i have to pick all the internals. Ive assembled plenty of engines, just never went through the process of picking pistons, cams and valves. This is a 2005 Silverado 1500 4x4 and i use the truck as a truck.

Im just wanting a basic rebuild but bored to 5.7. choosing 5.7 because i dont want to swap the transmission as well and im feeling nostalgic for an LS1.

My goals are simple, rebuild the 5.3 to a 5.7 but retain the reliability and drivability, im not chasing horsepower or redlines, but i want LS1 numbers, 350hp and 350tq. That'll be plenty for what i want and need.

Here are my questions, do i need a new cam profile to match the bigger displacement, if so, what should i go for? I want it smooth, not lopey or thumpy or whatever the kids say nowadays. Im totally ignorant to cam specs, so i definitely need help with this one.

What about heads? Should i keep my current heads? I assume mine are 706, but i havent scraped the gunk off to check, but the free long block i got has 706 heads, i dont think mine are not cracked as i have no coolant loss issues, just valve stem seals, but i have no history on the donor block except "it ran when my student swapped to a 6.0". Do i need to get different heads? If so, what will give the most reliability and efficiency? I plan on fully rebuilding whatever head i go with, another technical thing im kinda dumb on.

Finally, what pistons should i go with? Any brands to stay away from? Im thinking the hypereutectic pistons should be perfectly fine. I dont see a reason to spring for forged. Should i go with flat top or stay with dished? I know enough that the piston design can change compression, but i have no idea which way i should go..

I need to have my pistons chosen, and the block and heads stripped for the machine shop to do their part. Any help is appreciated, i can build the engines and throw parts together correctly, but chosing the right stuff is where i need help.

​​​​​Thanks alot.

TLDR: Im a dummy and need help picking the correct pistons, cam, heads and valvetrain goodies to bore my 5.3 to a 5.7 and rebuild it.

G Atsma

Iron 5.3s have enough meat to bore to LS1 specs. Then just use std. LS1 pistons.
Keep the truck heads, but be aware that you'll be getting a smaller chamber by about 6cc
Your compression will go to 10.99:1
If you can get some 243/799 heads the compression would be 10.44 due to the 65cc chambers on them.
The stock LS1 cam is pretty much the same as the LQ9/late LQ4 cam at 196/201, .467/.479 116 LSA.
Between all this you will have a smooth and torquey 5.7 truck engine

demonsmokr

Any other heads to look at? I started browsing marketplace and found a pair of LS1 241 heads for 200$ with rockers and covers. Also found a pair of bare 243s for 200$, seems a little too cheap. But i dont know.

G Atsma

The 5.3 706 heads are better than the LS1 heads because of the smaller chamber and slightly better ports. A good bowl blend and multi angle valve grind will improve them a lot.
The LS1 heads are usually not recommended.
As I said above, either keep and slightly mod your 706/862 heads (hey, you have them already...) or get some 243/799 heads which have better ports and larger chamber.
No other heads need apply here

demonsmokr

What do i look for in regards to damage when buying used heads? He agreed to 150$ for the pair. Why do i feel this is too good to be true? Am i just jaded from numerous bad experiences on facebooks and i cant tell when someone is selling a good thing for cheap?



Only thing i know to look for is pitting from nitrous, what else do i need to look for?

Ls7colorado

iTrader: (3)

150 for bare 243 head is about right