Side to side liner height variance

[dhirocz]

Didn't think this was a big deal, but the time to deal with things is now.

Cutting my counterbore, I am having a side to side variance of .0005, which I am attributing to either variations is deck height, tooling or a combination of the two. The deck is clean, the tool is centered. My target liner height is .014, ended up between .0145 and .014.

Am I correct in saying an acceptable range is +/- .0005" around the perimeter of the liner as well as liner to liner? I'm close enough where it would be very easy to go too far trying to take that little off, and would rather be over .014 than under.

This job has made it clear I need more precise measuring tools.

[Nilao]

When rawze cut mine I think it was .0135 on the intake and 14 on the exhaust....I forget the specs but I think the variance hole to hole was .002 but don't quote me on that...I'm sure rawze will be able to tell us to the nanometer later.

[Rawze]

(03-08-2021 )Nilao Wrote:  When rawze cut mine I think it was .0135 on the intake and 14 on the exhaust....I forget the specs but I think the variance hole to hole was .002 but don't quote me on that...I'm sure rawze will be able to tell us to the nanometer later.

Yours ended up at 0.017 initially" -- so we re-cut them and ended up at 0.014" on the second go around with about 0.0145" on the passenger side (where it should be if there is variance).

Cummins says the tolerance allowance between holes is 0.002".
Cummins also says 0.001" from one side of a hole to the other.

I have never cut one hole-to-hole with more than 0.001" variance between holes, not even the very front to the very back, and any more than 0.0005" within the same hole on one myself. That is when I was using digital gauges, and have abandoned them since.


After I did Waterloo's truck with him, I threw away all my digital gauges into the trash can and went back to using only old-school mechanical ones. I can get the machining a whole heck of a lot more accurate with mechanical gauges than digital. Since then, If I see the 0.0005" variance in the cutting tool starting to set in, then I simply change the torque of the retaining bolts of the counter-boring tool a bit and can correct for it easily before getting to the bottom of the cut.

I would imagine that also, with the hardened brass shims, a bit of variance would be more forgiving vs. someone using hardened stainless shims. I am not a fan of hardened stainless shims at all... but that is just me.

[dhirocz]

My variance for #1 is on the driver's side...that's where it is higher.

Is there a corrective measure for this, or is the .0005 not enough to pose an issue with the exhaust side being lower?

I'm trying to keep in mind that I have a number of variables here as well, so I'm not trying to be too paranoid, though my inner perfectionist is haunting me at midnight.

[Rawze]

(03-09-2021 )dhirocz Wrote:  My variance for #1 is on the driver's side...that's where it is higher.

Is there a corrective measure for this, or is the .0005 not enough to pose an issue with the exhaust side being lower?

I'm trying to keep in mind that I have a number of variables here as well, so I'm not trying to be too paranoid, though my inner perfectionist is haunting me at midnight.

sounds ok to me. just make sure your height is correct.

also make sure your measuring it without the anti-carbon rings installed yet too... and that you have used 100 ft-lbs of even pressure to hold a liner down to see what height it ended up at.

[tree98]

(03-09-2021 )dhirocz Wrote:  my inner perfectionist is haunting me at midnight.

I've been there lol. Not from cutting counterbores but I know exactly what you mean.