Quote:
Originally Posted by Mikael Nielsen
I have now aligned the crank and the cam as good as possible, and is now trying to turn the piston.
While removing, I noticed the upper rod bearing having some small scratches. Are these okay? Or do I need to replace all of them?
The previously owner replaced them all, but I am not sure if it's damaged.
Picture attached
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That is a lot of bearing damage if it only ran for a few minutes. As one of the other guys said, that indicates there was contamination of the oiling system when the engine was built. Check some more bearings for the same condition. Any bearing with that much damage should be replaced. If I saw that in an engine that was removed from the car, I would fully disassemble the engine and clean the block's oiling passages. That level of bearing damage is unacceptable for a motor you want to live a long time.
Also be aware you cannot just turn the rod around to fix the orientation of the piston. The bearing chamfer must face the outside of the rod journal. Usually this means having a machine shop press out the wrist pin and correct the orientation of piston to rod. Is this the only piston that is backwards? The notch or arrow on the top of the piston must face the front of the engine, and the chamfer on the big end of the con rod must face the outside cheek of the rod journal. The prevents the rod bearing from contacting the radius at the journal's edges where the crankshaft journal meets the edge of the crank throw.
Are you in the US or somewhere else? In the US, its fairly easy to find other heads. The 6X-8 heads are very low compression. I would find a set of 5C-4, 5C-9, or 6X-4, or 96 heads to use instead. If you're stuck with the 6X-8, then have them milled about .050" and check intake fitment.
Not a Pontiac but the basics are the same:
https://www.youtube.com/watch?v=F6hQ6W8jobs