Thanks for sharing your sonic test sheet.  Based on the numbers, core shift is minimal and this does appear to be a good block for boring out to a 292 size.  And you're right.  The minimum values are what you’re paying close attention to.

Lorena, Texas (South of Waco)

Oh that's cool. When you insert the link, it downloads it to the page. Sweet. So I can upload pics. Nice.



Also, one more side note. He measured the full thickness along all the walls and only recorded that absolute minimum thickness of each cylinder, per 4 theoretical sides, and top and bottom. Meaning, that he the numbers recorded are the thinnest parts of the cylinders. So, there's more meat there than what he's showing. If you're going to err, err on the side of smaller thicknesses to really understand all the weaknesses right?

Heber City, UT (15 mins outside of Park City- basically it's in the mountains)

55 Effie

So, when I got to add an image it only offers the option of adding a direct link. It won't let me browse my computer for files/images. But, here is the link the picture that maps out the wall thicknesses.





Heber City, UT (15 mins outside of Park City- basically it's in the mountains)

55 Effie

Here’s the link to the picture posting instructions.  Pay particular attention to the sizing so that the text doesn't roll off the screen.

http://www.y-blocksforever.com/forums/Topic34535-6-1.aspx

Lorena, Texas (South of Waco)

Turns out I don't know how to attach a pic. It's asking for a URL and it's on my desktop, not in the world wide webs. I'm gonna take a lunch break, when I get back I'll post them on the net, and upload it that way. Thanks again.

Heber City, UT (15 mins outside of Park City- basically it's in the mountains)

55 Effie

Ooops.  Sorry about that.  Thought I was looking at the difference between the two banks.  That 0.1475” value would be more than adequate for what you’re doing.

Lorena, Texas (South of Waco)

That minimum number of .145 would be after it's bored. My scanner's giving me grief. Hang on a second while I retry the scan and post it for you're viewing pleasure.

Heber City, UT (15 mins outside of Park City- basically it's in the mountains)

55 Effie

That minimum number of 0.1475” becomes 0.085” after boring to a standard 292 bore size if offset boring is not being performed.  That’s a bit on the thin side to be comforable with.  Average numbers don’t mean much when sonic testing as you are really looking for problem areas which are thin spots or core shifting.  Averaging tends to hide these problems areas.  A picture of the sonic test sheet will give a better idea of what you really have.

Lorena, Texas (South of Waco)

I've got the Sonic Test results from my machine shop this weekend and I'm wondering what you Y Blockers think. It's a 272 standard bore. The measurements came out about like this:



avg wall thickness: .226"

min wall thickness: .217"

max wall thickness: .241"



The thickest walls are the 1-4 cylinders, and the thinnest walls are the non-thrust side of the 5-8 cylinders. If we bore that from a 3.625 to 3.750 that's going to take the wall thicknesses to about these measurement:



avg wall thickness: .1630"

min wall thickness: .1475"

max wall thickness: .1785"



I've heard it's good practice to try and maintain about .180" as a minimum wall thickness. +or- .015" with the average at .1630, my machinist is absolutely fine with boring it up to a standard 292. What has you're experience proven with these Y's? If you guys needed I could post a more elaborate description so you had a better picture of the cylinder wall thicknesses. Thanks for you're help.

Heber City, UT (15 mins outside of Park City- basically it's in the mountains)

55 Effie