I just got the motor back in the car. It runs great, I finally have a heads and cam setup + a built bottom end . The cam is my old arlington motorsports grind that my brother gave me(it was in my pewter z28 when i sold it), the heads are patriot stage 2 ls6. Im using stock crank, wiseco coated forged pistons stock compression ratio, esp eagle rods, arp complete engine stud kit etc. I put Gm break in oil in it, how long do i run the break in oil and is it ok to break the motor in while its untuned?

 

anywhere from 500-1000 miles

 

500 miles is fine, but like 68bird said, dont go more then like 1000 because you are going to have all the oils and such from the new cam and metal debris floating around in there, my opinion is to change it right after its broken in, because the longer you leave that stuff in the more damage it could cause

 

I always try to have the oil changed for the first time on the lift. We run the engine through a few heat cycles and then change the oil. I don't want any debris floating around in there for 500 or 1000 miles...

JMHO....