Piston ring excessive end gap after bore 0.5mm over.

[CrazyAndy]

Hey all.

So I finally got it into my head to check the ring end gap in my block with the new Goetze rings I have.  The block is bored (or I told the machinist, so should be) 0.5mm over.  Rings are Goetze part number 08-990107. 

Tried the first two rings in all cylinders from all four of the packs, and the ring end gap check out as 0.019"-0.028" on the 1st and 2nd compression rings!!  What the fraggle rock??  Did my machinist screw it up and do a run-of-the-mill ".020 over" without caring?   Did I get the wrong rings?  Should I try a pack of 1mm O/S?

Really wish I had a dial bore gauge on hand right now; too spendy for a one time use though.  I'll probably take this to a more local machine shop who can measure the bore for me.  Hopefully I just got some bad rings; I just finished painting the block.

[CrazyAndy]

To copy-reply from my build thread, the machinist looks to have boogered up my re-bore.  I used  a digital dial bore gauge calibrated to 80.01mm to  check bore taper and out-of-round.  Here are my readings.  Note all measurements are plus the above measurement baseline, and (H)horizontal is correspondent to viewing the block deck, with the front of the engine as 'bottom':

              H               V
C1
T       0.026mm     0.028mm
M      0.014mm     0.022mm
B       0.030mm     0.026mm

C2
T       0.034mm     0.032mm
M      0.016mm     0.032mm
B       0.032mm     0.030mm

C3
T       0.032mm     0.034mm
M      0.020mm     0.038mm
B       0.036mm     0.036mm

C4
T       0.028mm     0.026mm
M      0.020mm     0.024mm
B       0.036mm     0.032mm

After running some math on circumference of the cylinders (in inches on that), I determined that these measurements would increase any new  ring gap (0.007"-0.015") by 0.001727"-0.004676", which I'll round/simplify to 0.002"-0.005"
So as it seems that would be the reason behind my recently-measured excessive ring end gap, which measures anywhere from 0.024"  to 0.031".

Now I'll have to get the block bore out ANOTHER 0.5mm, to 80.51mm, but not by the same machinist.  Really pissed right now.  Why the hell can't anything NOT cost me more money?  :evil:

NOTE:   I'll admit I took these measurements with the main caps not torqued, but the top and bottom measurements I think speak for themselves.

Lastly, at least the piston skirts measure in correctly at 79.98mm exactly.  Too bad it looks like I'll need another set.  

[camboscams]

If you can't find any shops to take car of it over there, or Bill won't right his wrong, you could haul the block over to me and i could get you taken care of. Just let me know and we can iron out the specifics