I got my preliminary report back on the 455 from the machine shop today. I was actually surprised by the news because I've often read that Pontiacs rarely need line boring. Either way I'm just glad the block is good. I'll be able to start buying some parts before long. Here's what the machinist sent me in an email:
"The block is clean, and passed a magnaflux test with flying colors. Inspecting the bores shows that the block will easily clean up at +.030, and would probably even clean up at +.015 or +.020, should that be needed. Additionally, sonic testing the bores reveals this to be a healthy block in terms of wall thickness. I will provide all the numbers in the report, but I would be confident boring this block to +.060 if that should ever be needed.
Now the bad news. In checking your main bearing bores they are all in alignment, which is good, but they all vary in size, which is bad. They are all at the high limit of the specified bore size, and several are larger. Several are also out of round. While this can be easily corrected by line boring/honing, I was hoping to get by with out those procedures. Unfortunately it will be required for this block.
Additionally, the deck surface has a few spots of erosion. I am guessing its the result of weak antifreeze. It is not a problem, as decking was high on the list of priorities. It will just require a bit more of a cut on the decks.
So what we are looking at is a line bore, bore and hone cylinders with a torque plate, and decking. I still feel that balancing is a priority, and I will work with you to make that happen. Additionally, you may want to consider upgrading the main cap hardware to studs, or even installing 4 bolt caps on the center mains. Not required, but since work will be done on the mains, now is the time to think about it. We can discuss that further should you have any interest in those options."
"The block is clean, and passed a magnaflux test with flying colors. Inspecting the bores shows that the block will easily clean up at +.030, and would probably even clean up at +.015 or +.020, should that be needed. Additionally, sonic testing the bores reveals this to be a healthy block in terms of wall thickness. I will provide all the numbers in the report, but I would be confident boring this block to +.060 if that should ever be needed.
Now the bad news. In checking your main bearing bores they are all in alignment, which is good, but they all vary in size, which is bad. They are all at the high limit of the specified bore size, and several are larger. Several are also out of round. While this can be easily corrected by line boring/honing, I was hoping to get by with out those procedures. Unfortunately it will be required for this block.
Additionally, the deck surface has a few spots of erosion. I am guessing its the result of weak antifreeze. It is not a problem, as decking was high on the list of priorities. It will just require a bit more of a cut on the decks.
So what we are looking at is a line bore, bore and hone cylinders with a torque plate, and decking. I still feel that balancing is a priority, and I will work with you to make that happen. Additionally, you may want to consider upgrading the main cap hardware to studs, or even installing 4 bolt caps on the center mains. Not required, but since work will be done on the mains, now is the time to think about it. We can discuss that further should you have any interest in those options."
