Measuring cylinder bores using a dial bore gauge | DIY

When you are measuring any cylinder bore you are looking for three things, bore size, taper, and out of round. In this episode of DIY, Davin demonstrates how all three can be quickly and accurately measured using a dial bore gauge.

#DIY #DavinReckow #DialBoreGauge

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[autka_me]

Interesting to see slightly different approach. What I do is I set micrometer to what bore size is suppose to be, 'zero' bore gage on it and then measure like in video: two measurments perpendicular to each other where rings are in TDC, then again in half of piston travel and where rings are at the bottom of the stroke. This way the reading shows how much bigger the bore is if from what it is supposed to be. This doesn't matter really, just my simple brain has less thinking this way.

[TimsWorkshopTJY]

Haven't seen one since I retired at Boeing. Our machine shop Quality control used them to measure trunnion bores on the landing gear. They took inside and outside measurements at 12, 3, 6 and 9 positions. When we found issues it was usually the nickle/bronze bushings wore out or not built right. Out of tolerance and had to be replaced. Bore gauges are very expensive and there was a limited amount there and have to be recertified when due or dropped.

[thelandcruiserproject]

Just started my build and I am not even done taking it apart. The part I am most excited about is defenetly rebuilding the engine.

[ekscalybur]

This is the high quality content I'm subbed for, more Davin please!

[simongroot]

When I was using them in powertrain development we measured on the wrist (gudgeon) pin axis and at 90 degrees to that axis. The major wear in the cylinder is perpendicular to the pin axis. Measuring at 45 degrees to the pin axis will not capture the maximum wear which means you could order the wrong pistons. Always set the micrometer to the bore nominal and work off that. Measuring at some arbitrary point in the bore means you have to do a whole bunch of calculation to arrive at just how far out the cylinder is from nominal. The machine shop only cares how big the bore is so they know what size the new piston needs to be. They bore and hone to the pistons plus running clearance

[scotte]

the thing is, the machine shop will look at the largest bore measurement as the single most important measurement.
Indication of taper and out of roundness are factors,
butt,
that sort of data is actually more useful in diagnosing the current condition and past history of the engine.
Ultimately, once the block is to be re-bored, they will be bored and honed to the smallest diameter that will clean up the largest measured diameter and still be "in-spec"

[kieranmann]

Great information clearly explained. Thanks

[farhadalaee]

Smooth and clear explanation
Good luck

[kw]

Those things are fun to use. Takes a second to get the feel though.

[Kreisverkehrdrifter]

Hey mate, i´m using a measuring gauge from germany (schwenk lmt) it works since 30 years

[randallsemrau]

6:40 'This is a comparator, more than it really is a measuring device'. This is the key statement needed to provide proper context, immediately at the beginning of the bore gauge demonstration.

[josephreisinger]

Brings back the time I was in motorcycle school. Try doing that with ports in a 2 stroke cylinder.

[scotte]

measure once, cut twice; measure twice cut once. That old chestnut might be good for woodworking,
BUTT,
for the REPEATED precision needed here, (remember you have to match ALL the cylinders) you need to be ready to take a lot of time,
AND,
document . . .EVERYTHING!!
It is a very good idea to have a notebook to write all this stuff down in.
Part numbers. measurements, actions taken, discussions with machine shops, etc.
It's not just essential for the rebuild, you WILL need that info if anything goes wrong, and if you want to sell it down the road, that sort of documentation can really sweeten the pot.

I would like to see how Davin keeps track of all this.

[GianniTRW]

Excellent video and explanation. And funny coincidence because the sample block in the video is a Chrysler big block, and that's what I am working with. Guess I got lucky! Thank you for the info

[giancarlopbranco]

Congrats and thanks Mr Davin! 👏🏻👏🏻👏🏻👏🏻

[ManicSalamander]

Good to see the way you handled and used these instruments. I have seen/ done enough to know that technique is critical to a consistent reading. I have snap gauges, that's my best tech right now to measure bores. But I am suspicious that I cannot trust them down to .0001" with my current techniques. Do you have any advice on how to take an accurate measurement with a snap gauge?

[PlasmaJunkie]

Was there a follow up to this? I had no idea I was so into precision measurement. This is fucking awesome.

[alantownsend]

Why is he measuring diagonal? The most extreme wear will occur near the top of the bore (as he observed; but because of the higher pressures forcing the rings against the wall) and perpendicular to the axis of the crankshaft (90 degrees to the wrist pin). This is due to the skirt of the piston being pushed against the bore wall during the compression (minor thrust) and power strokes (major thrust).

[Xsidon]

can you also set the dial bore gauge to the measurement specified in the service manual of the block and just look if it's within the accepted value range?

[leonangus]

This is a great video, but wouldnt it be quicker to 0 the bore gauge on the micrometer (by setting micrometer to OEM cylinder size) and then simply take the thrust / Axial readings on each cylinder up and down? I guess there is many ways to do it no?