I have a friend that is a GM LSx fan. He is working on an upgraded LS motor using a "formula" approach recommended by others on the forums. During planning he was picking my brains on my thoughts about his project. Needless to say that he did little of what I recommended.
Fast forward to recent times. He is now on the 4th rebuild of this same project. The previous attempts suffered various "problems" related to assembly "errors". EVERY one was preventable if someone had more experience and/or double checked their work. What would your thoughts be after the 3rd time to remove the motor?
One of my recent projects was to rebuild a GM 3.5 for a 2007 Pontiac G6. The prior owner had run it low on coolant. The motor over heated and threw rods out the side of the block. With the help of my local machine shop, he helped me to pick the best parts from (3) core motors to create one working motor. New rings, bearings and gaskets were added to the mix.
Looking back on the project, the experience of the machine shop provided me:
- with the assurance that all clearances were checked to be sure they were within "standard" range.
- the heads and deck were flat
- there were no hidden cracks
- the heads were completely checked and ready for bolt on. Wear parts replaced.
- The bore of the block was measured. Only a slight re-surfacing was needed. No over bore.
- Perhaps the MOST important thing was just how clean everything was. The parts were so clean they looked brand new. It made so much difference not having to worry about external dirt getting inside the motor while it was being assembled. This was an important "lesson learned" for me. I was surprised just how hard it was to keep everything clean during assembly.
Recommendation. If budget is really a top concern, did you really need new pistons? Were the old one's even checked?
Bottom line. For a true budget rebuild it's hard with today's high cost of labor to rebuild a motor and do it right. I generally recommend if $$'s are really that tight, the use a whole salvage yard motor.
This is your project and you should do what you think is best.