Anyone want to guess what these numbers are, and what they respectively represent? No poll this time. Cake won the last one hands down.

You're doing Common Core math? But in all seriousness the only one I have a guess on is RA for the surface finish on the deck.

Ok, I will admit first off, I cheated. Still learned something new though. Not gonna spoil it though.

Like Cuda416 said, those are surface finish roughness tolerances if you were to measure the surface with a profilometer. I'm helping my son do common core math right know and I feel like jumping out the window. Its like they ask a Doctorate level psychologist to rewrite math. It is a giant load of BS.

A lot of common core math is just mental math but on paper. I was never good at mental math but the more I use it the easier it is to do

I wish. My old boss bought a new hone and the profilometer so I had him touch up the bores on my junker for me and he gave me the numbers. Way too much fun (and work) to keep up with current technology.

Ok, off my memory so remember that... Rk is the core roughness value. It gives you the idea of how rough (or fine) the finish is, but without the other numbers it doesn’t mean too much. I mean it’s important but you can’t really define what you have without the rest of the numbers. Rpk is the distance from the mean on the Y axis to the highest peak. Rvk is the distance from the mean on the Y axis to the deepest valley. Ra is the arithmetic sum of the absolute values of the peaks and valleys over the length of the measurement. Keep in mind the mean for RPk isn’t the same mean as Rvk, because the mean line is related to the average of the distance across the peaks and the Rpk mean is the average of the distance of the valleys. Now, to evaluate all that math requires knowing what rings you have, piston speed, the hardness of the block, fuel used, NA or power adder...and probably some other things I’m forgetting. The best thing to do is call your ring manufacturer and tell them what you are doing and they will tell you what the finish SHOULD be. Hitting those numbers can be a bear if you haven’t honed that particular brand of block or sleeve before or if the manufacturer changes the hardness of the block or sleeve. Compacted Graphite blocks do not hone the same as the run of the mill SBC block, which happen to be the softest blocks (BY FAR) of the big 3, with Chrysler being the hardest and Ford not far behind. Any aftermarket race block should be harder than an OE block. That changes the finish required. And I can say after watching the new hone work that it’s near impossible to get the numbers correct on a non CNC machine and especially with vitrified abrasives. The profilometer doesn’t lie. I also forgot even the engine oil used can change the surface finish.

Wow Tim, that's quite some brain you have ! Thank you for the reply, way over my pay grade as a carpenter/mechanic lol. But I appreciate it nonetheless

Here's a pic of what the profilometer sees (measures). The peaks and valleys and well as overall flatness/waviness (or deviations there of). FYI - These pics are a surface that is greatly magnified:

You look at and see and feel a surface, like a freshly bored and honed cylinder, and it looks smooth and flat and shiny.................................but it's actually extremely rough and not very flat. The machine shop does its' best to get it as uniform and smooth as possible but the profilometer does not lie!!! Remember - if it was too smooth the rings would never seat!

Okay yeah that makes sense, machining is a trade I'd love to get into..so how does the profilometer work ? Is it like a radar reading depths?

Dingle ball hone and iron rings...... Lather rinse repeat.....good for another 50K. What emissions? Farmer John.