i just bought a running 4.8 with trans for 1100. ran grate but i removed the 709 heads to port and polish when i found this ugly sight. i was planing on changing the crank to make it a 5.3 but if i also need a rebuild might as well get ls6 pistions. but if i dont have to i wont. the cylinder walls look clean but piston head are coated with the flacky black stuff

 

that is grounds for some serious cleaning i'd say. Honestly, if you have the engine out and the top end tore off, why not go ahead and refresh it; new rings, arp rod bolts, make sure the bearings are all good, etc..

 

thats carbon build up its normal you can clean al lthat off

 

great all she needs is a cleaning then. how should i clean it off. im thinking with a little diesel.

 

I would run that. Its normal for street driver truck motor like that.
I would just hand wipe them, I wouldn't use a solvent.

a shortblock like that might run 8's or might kick 2 rods out pulling out of the garage.

 

+1....you got a motor that was babied, almost never over 1/2 throttle. Slap it together and run the **** out of it. CC did a TT build that put 23 lbs of boost through what they thought was a bone stock 5.3 straight out of a junkyard....turned out to be a 4.8 and it put down 1157 hp. BONE STOCK!

Build it, run it, blow it...then spend $700 and do it all over again!

 

if you want to run LS6 pistons you have to bore the cylinders ~.120 over. This should cost around $300 depending on the shop.