Epro

iTrader: (1)

Motor has 137,500 miles on it

It's a 5.3 taken out of a GMC Sierra, building it for my 95 camaro. It's an iron block...

I was going to take the heads into a machine shop and get a valve job done, new valve seals, and have the heads plained. But I might get a slightly used set here! What exactly do the numbers describing the heads in the classifieds mean? Hard to explain... (317, 243)

If I get a stock LS6 cam, will I need LS6 valvesprings?

Epro

iTrader: (1)

anyone?

PREDATOR-Z

those are casting numbers. You are going to build a 137K miles motor?
Take it from someone that did that many years back as a newb, DON'T.
You can rebuild the iron block and bore it to a 5.7L (346 ci), and as you said get a set of used heads in good condition. Either 5.3L or LS2/LS6 ported.

Epro

iTrader: (1)

By build do you mean rebuild? Or add performance parts like a bigger cam?

I figured I'd be safe with the stock cam out of an LS6?

Jason 98 TA

iTrader: (4)

We offer cnc porting on the 5.3l heads for $650. We can build you a 2.00" 1.55" valve 5.3l head using stock GM valves to keep the pricing down