Bansheeman6100

so im finally getting around to the LS for my 1972 restoration, and had a couple more questions. i got around to getting the heads and oil pan off, and discovered that the piston lowest in the block had water in it at some point, and has a bit of rust. depending on how bad it turns out to be, i may end up having to tear it down and t\have the block and hears gone through. my initial plan was inspection, cleaning, and new gaskets. the motor is a 5.3 from a 2000ish silverado. if i order a rebuild kit, should i order ir for a silverado, or something else for performance increase? i also need te replace the oil pump, and not sure which model to go with. the oil pan did include the shorter pickup. i will be running a camaro oil pan for clearance. i am also considering doing a Jegs cam, with some form of lifter/spring/rod upgrade as well. i am on a budget though, and also dont want to go so aggressive as to require another retune.

Mercier

iTrader: (15)

A few notes to get you started. If you have rust in the bores, you are 95% likely going to need to bore it which means larger pistons and rings. If you are committed to that block, know that a 5.3 iron block(LM7) like yours can be bored all the way to a 5.7 safely. So if you are changing up the rotating assembly, why not get the extra cubes? Find yourself a set of nice used LS1 pistons and have the assembly balanced by the machine shop. This is the path to budget iron 5.7. The LS1 pistons will also increase your compression ratio nicely. The heads have a slightly smaller intake valve but troll the classifieds a while and you can find some factory LS1/2/6/later truck intake valves and have your machine shop cut the existing seats out for the 2" valve for fairly minimal money. On those, it does not require installing a new seat.

That being said, if you have rust in the thing, consider that a nice-running 100k-ish mile 5.3 that will require no work and run another 100K miles is under $500 generally. If you need to bore the thing, it will always be cheaper to find another with no damage.

Oil pump--Melling 10295 or 10296 if you want to peg the pressure gauge all the time. The 10296 is a beast and worth every penny IMO.

Only cam that you could slap in a 5.3 and run without a retune is going to be something between a factory LQ9 and factory LS1 cam. Even then, avoiding the expense of a tune is a poor mindset I think. A proper tune to match your parts has exponentially greater bang-for-buck factor than any actually parts. So budget the $300 or so for a proper tune from an experienced and proven tuner and buy parts with what $ is left over.

Now the LS1 cam is proven to perform well in the LM7. See this article for some great starter reading about what the 5.3 is capable of with stock GM cams and a couple of Comp sticks:

http://www.hotrod.com/articles/ls-cam-test-comparison/

Cam Motion is the vendor I prefer for cams and I think you should consider them first. Top notch. They can set you up with a great cam for a decent price that should allow you to use your stock pushrods, retainers, locks, and some ~$60 LS6/2/3 valve sprigs as well as very affordable LS7 or Morel drop-in lifters.

Good luck with your build.