Measuring cylinder bores using a dial bore gauge | DIY

[@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.

[@scotte2815]

more than one way to skin a cat. The trick is to understand and keep track!

[@funone8716]

You would be doing it the correct way. Unlike this vid shows.

[@nickpappas4133]

I’m a retired Audi tech and there is a concern about oil consumption on 2 litre motors and your right that is the proper way to measure cylinders as per factory.

[@scotte2815]

@@nickpappas4133 I imagine the the factory has direct measuring bore micrometers and skip any need to transfer from one instrument to another.

[@alantownsend5468]

@@scotte2815 that's the beauty of bore gauges (when used properly), there IS no transfer. The gauge is calibrated/zeroed in a fixture of a given dimension and then the dial displays how far the bore deviates from that calibrated value. If I understand correctly, this is the MOST accurate way for a human to measure the ID of a cylindrical bore.

[@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.

[@ekscalybur]

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

[@scotte2815]

He gives us the tools that are most important, know how and confidence.

[@thelandcruiserproject5421]

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.

[@simongroot7147]

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

[@alantownsend5468]

"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." This. He even says "this is a comparator more than it really is a measuring device" in the video; so why not just set the mic to the "correct" bore spec and see how off it is?

[@whiplashmachine]

Usually where the rings stop at TDC is where you'll find the most wear in the cylinders. When cylinders get worn by the skirts to the point that is the major wear spot you have had an issue going on.

[@zachrysmith9138]

Just to be clear you are setting the micrometer to the nominal bore which is technically supposed to be 4" so in turn by zeroing the bore gauge to the NB of 4" so one can actually measure the true measurement of the worn bore?

[@chazmakarowski5429]

@@zachrysmith9138 you can do it that way, yes, but only if you have a high quality dial indicator that reads accurately. A coworker of mine recently bought a no name bore gauge from an online store and when I tested it out for him I found readings were out as much as 0.004" over 0.010" of movement because the dial indicator is just that bad. That sort of low quality dial indicator is really only good for comparing rather than measuring. A name brand bore gauge will be accurate enough to measure with. Keep that in mind

[@scotte2815]

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"

[@Jagharjusagt]

@@scotte2815 butt 😛

[@farhadalaee2682]

Smooth and clear explanation Good luck

[@kieranmann9761]

Great information clearly explained. Thanks

[@kw2519]

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

[@fsj197811]

Good video, thanks for sharing.

[@2HacksGarage]

Great video

[@leonangus1]

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?

[@Kreisverkehrdrifter]

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

[@mounirboroumi4300]

Brother how much you buy it pls ?

[@randallsemrau6911]

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.

[@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?

[@shanepascoe1078]

At a guess, that's how the machine shop likes to receive their information. In would do what you said, set micrometer then transfer that to bore gauge and then do your 6 measurements.

[@funone8716]

You could do that yes. But that would be the correct way to use the bore gauge. See what I did there?

[@alantownsend5468]

Xsidon, that's how I was taught to use them

[@funone8716]

@@alantownsend5468 As a machinist in the trade for 43 years and having rebuilt many engines, Xsidon's way is the correct way It's annoying to see so many misinformed youtube videos showing people the incorrect way to do things. Misinformation.

[@jeeprenegade1985]

I would wring gauge blocks together to the book's nominal bore size. Set up the dial bore gauge to that block set and set the dial to zero. We used to put a small sticker on the gauge then. "0 = 4.350" for example. Transfer measurements, like measuring the dial bore gauge afterwards with a micrometer is not accurate.

[@muhdhafiidz1206]

Thanks MR.Davin

[@scotte2815]

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.

[@scotte2815]

Do we all understand the need for ensuring that the final machined dimensions MUST be the same for ALL the cylinders? The rotate mass not only needs to balance, the force in each cylinder needs to be applied to the same area. This applies not only to the bore but also to the crank journals and bearings as well.

[@virimaimutsatsa311]

Very educative

[@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?

[@josephreisinger33]

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

[@giancarlopbranco]

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

[@qeisabd8264]

Really Good Job

[@dannychiguina3962]

Great Tip's Thank you

[@alantownsend5468]

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).

[@QualityExpertVlog]

Thank you Sir for the information❤️

[@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

[@PlasmaJunkie]

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

[@ronlynch7744]

Cool stuff for accurate builds. 😎👍🇨🇦

[@khaledyacine6198]

Thanks

[@sonyhk3824]

Great info

[@jacob-67tune18]

Thank you

[@ralph5063]

What tolerance do you typically allow for taper and out of roundness? I just want to hone and re-ring. My manual doesn't have these specs.

[@panagiotis1519]

Nice explanation :)

[@ALKUKES]

How fare do you take the measurement deep down ?

[@josealtamirano6929]

@Hagerty suban la restauración de un motor toyota 1989 v6 3.0l 3vze de favor seria un buen video.

[@obsbarlos]

Yes sir thanks for the video really helps! 🙏🏼

[@josephm.6453]

A calliper logging tool can be made to record a better reading and create a 3d image. The one used in the oil and gas industry is less sensitive since you don't need this much precision but you can manufacture a similar device based on the same concept. Heck you can even use laser instead of the prongs to get an extremely accurate reading. This is not hard to manufacture since theodolites use the same concept.

[@Djm9393]

Full sending never lifting 😏 🤙 mobbin deep 🙌 knowledge is power 🔋

[@woshanharshana7087]

Can we get the cylinder diameter with Verniur caliper,and after adjust the bore guage with that Sims and adpater

[@jordanhowell3870]

if i am doing a small bore cylinder like say an 80cc dirtbike cylinder would i be fine with just checking two different spots in both directions or would you still do three spots a top middle and bottom in both directions

[@Genrebenders]

I usually just do two but if you wanna make certain then go 3.

[@wickiezulu]

Does Bore Pitch determine an engine's likely displacement range or are there other factors involved?

[@cosmicexplorer42]

That's interesting, I've never seen a dial bore gage used like that. I've always used a height gage to set zero instead of measuring it with a micrometer.

[@ct1762]

what do you think the "bore" in dial bore gauge refers to? how else would you use this tool?

[@alotl1kevegas860]

Can we get links to your micrometer sets? Please and thank you. I noticed the bore gauge is Fowler. But what about the Micrometer set, and telescopic gauges? Much appreciated 🙏

[@kw2519]

Fowler is actually kind of considered the bottom of the barrel. You can find these things in a MSC catalog or any other manufacturing focused catalog. Be warned, they aren’t cheap. OD mics the size he’s showing, are really expensive. The good brands can get into the thousands per micrometer when you get over 6” and you’ll need a new mic for each inch graduation.

[@kw2519]

Also I don’t trust a snap gage like those, to less than a few thousands. You can easily pull it off square and allow it relax more than you realize.

[@bobsponge1877]

Is fowler one of the better brands of gauge?

[@ct1762]

bottom of the heap, but perfectly fine as its quite accurate down to 1/2 thou or slightly better. I just want to know if my bores are in spec, what size they are, and if they will clean up with the room available. i never hone anything but small motors. anything 40hp and up they all get bored as they are all out atleast .002'' anyway. if the limit is .003'', look at that as 75% worn. then guys just chuck a ball hone down it, new rings and call it good. sloppy stuff IMHO.

[@shahzadahmedt]

Measuring tools used in mechanical workshop

[@Russeljfinch]

What brand dial bore gauge would you recommend? Lots of chinesium crap out there

[@scotte2815]

Shop around, your budget will decide what you get. American or German brands are through the roof. The Japanese brands are more affordable and very good. You might, MIGHT, get by with cheap crappy chinesium. If you go that route expect crunchyness and slop. Sometimes you can take it apart and clean it up, but I wouldn't risk it. You really need good repeatability, and part of that is practice, practice, and practice. then, practice some more. If you don't like your measuring instruments then they won't tell you the truth.

[@tjdorsey654]

Sunnen is the best, Mitutoyo is very good.

[@whiplashmachine]

If you just taking a measurment like in the vid to check wear or size, you don't need a bore gage. Inside mic or even telescoping gages would work, they just take a bit more effort to get same results. But them $100 Shars gages all over Ebay are not bad for a comparison measurement. I use mostly Sunnen bore gages but own Mitutoyo and Starrett bore gages also whiich are way cheaper. Example, My Starrett 2"-6" was like $400 CAD but my Sunnen 2"-6" was around $1800. They both give me accurate data. I actually use a cheap Shars gage in my honing cabinet and use my nice gages everywhere else.

[@fernandohood5542]

So how do I get an absolute measurement?

[@royshashibrock3990]

I am clearly missing something here. The way he is using the bore gauge, he just as well could have used the snap gauges. I am not a machinist, but I was under the impression that a bore gauge can be used to actually measure the bore size.

[@billdavies6463]

To avoid confusion, the term 'snap gauge' already refers to a fixed go/no go gauge for outside diameters, like you might test a diameter using a locked micrometer. This has an over 100 year history. The telescopic gauge, referred to here as a 'snap' gauge, goes back to at least the 1930s. I wish manufacturers would not reuse the names of existing, and still used, products. Silver solder is another example of renaming in the field of engineering. Thanks, Hagerty, for the interesting video.

[@davidholmes5698]

I DON'T have dial bore gauge i use plastic gauge for my rods and mains i dont know how to gauge my bores i checked my bores with old piston ring for the size bore i have 3.8 229 gmc caberallo 1981 my bore size is 3.736 my crank journal is 0.24 the rod bearings is 0.0021 main caps is 0.024. When i check the bore with my rings it's 0.035 on my feeler gauge

[@whiplashmachine]

With 0.035" ring gap on a small bore like that, your rings are ready for a big shot of nitros lol

[@SOLDOZER]

Recipe for disaster with that gap unless you need 1000 shot if nitrous.

[@Anarchy-Is-Liberty]

Well, before I can get out in the shop and get my work done, it appears that I have to spend about $5000 on added tools!!! FFS!! Over a year now since Davin has done any "how to" videos such as these, guess we're on our own now!

[@speedracer3033]

So what do you do for ring gap?

[@salazam]

Use a wooden block and two pieces of yarn with knots tied in each end. Wrap the yarn around the ring and mark on the block your starting point. Pull the knots together until the ends of the ring touch. Mark the block again. Subtract the difference between the two knots and the two marks on the block. That's your answer.

[@rogermoeller7350]

You are using the telescoping gauge incorrectly. You should snug the lock with the gauge larger than the bore. Then drag it like you are with the with the bore gauge "pogo stick" to find the shortest distance of the cylinder which is your true diameter. When manufacturing engines we had a standard to set the pogo stick to and then make your measurements to check over/under size.

[@austinlane5533]

Have you watched this channel? I'm pretty sure the man knows what he's doing at this point in his career.

[@chazmakarowski5429]

@@austinlane5533 using a tool wrong is using a tool wrong regardless of experience. Regardless, it's the wrong tool for the job anyway. Telescopic gauges are used for non critical features as they're extremely hard to use to measure more accurately than 0.001"

[@austinlane5533]

@@chazmakarowski5429 He knows what he's doing. It's all good.👍

[@chazmakarowski5429]

@@austinlane5533 anyone who knows how to measure would learn that they couldn't trust any measurement this guy gives them. For DIY material this is horrendous. Expect better from someone claiming to be an authority on the subject

[@salazam]

@@austinlane5533 0:41 Homeboy called his calipers a micrometer. Nobody edited it or fixed it. Sure, slip of the tongue maybe... not very professional to just roll with it. Especially on an "instructional" video.

[@thomasrenia]

Best mechanical!

[@jeeprenegade1985]

I used dial bore gauges in the machine shop a good bit, but we set them to precision guage blocks. In this example, put 4.350" gauge blocks together and set the dial bore gauge to zero. Each bore will be very close to that. Transfer measurements, such as measuring the dial bore gauge with a micrometer is not as accurate.

[@whiplashmachine]

Setting the bore gage to your mics is just fine. Espesially when you used that mic to measure the piston and now want a comparison. It is an exact transfer. I also do precision measuring at work which is a manufacturing machine shop and I've bored and honed a few thousand engine blocks over the years since I spent some time in automotive machine shops.

[@zachrysmith9138]

@@whiplashmachine Just to be clear you are setting the micrometer to the nominal bore which is technically supposed to be 4" so in turn by zeroing the bore gauge to the NB of 4" so one can actually measure the true measurement of the worn bore?

[@whiplashmachine]

@@zachrysmith9138 not sure exactly what your asking, sorry.

[@jimmy_dirtbike]

Holy smokes I cannot follow how to do this. I have watched this video three times.

[@alantownsend5468]

That's all great and all... but that wooden box for the mics!

[@davidholmes5698]

Im doing everything old school way that i was teached im 63 years old

[@SOLDOZER]

Teached? WTH?

[@joblessalex]

I thought the machine shop did all this for you?

[@wearegame777]

.030" over 440

[@andre-jrlaroche8986]

You use 0.001" micrometers to measure engine bore diameter? No meed to go to .0001"?

[@philincaundo]

I think the first tool was a lot less cumbersome, actually. Lol.

[@joshuagibson2520]

Not as accurate or repeatable though.

[@californiajones619]

Laser anyone?

[@ichiro3430]

How do i know is perpendicular so i can make it zero what if its not accurately perpendicular😮

[@apex_clutch6893]

Perpendicular will always be the smallest value, once you leave the perfect 90° the distance gets larger

[@doug595959]

a 350 sbc bore dia. is 4.000 and there are tolerances for this but you set your dial bore gauge for the known value. of your cyl. then measure your bore in a cross pattern and x pattern 1 in. from top in middle and 1 in. from bottom. this is how i do it i'm no expert by any means.

[@woodey028]

440s rule

[@ct1762]

what machine shop relys on the customers numbers to bore a cylinder? Bizarre!

[@dragospahontu]

Just pop some water into those things

[@تفسيرالأحلامونصائح]

أنا أفسر الأحلام ومرحبا بكم عندي 💕💕

[@horseshoe182]

fowler is Chinese brand, isn,t?

[@MalindoWe]

cumbersome

[@chazmakarowski5429]

Doing things this way, the best thing he could say to a machinist is that the bore is out of round/tapered by some amount. For a guide on how to measure he didn't measure anything except for the top of the bore with his calipers (which he called a micrometer once) at the very beginning. Write a script so you don't mix up terminology, or use incorrect terminology in a video aimed at people as an introduction to the topic. Or better yet, find someone that knows what they're doing to demonstrate and describe techniques. This was absolutely painful to watch and think that people "learned" from.

[@spiritbuu]

There HAS to be a simpler method of measuring bore size…this is way too complex and cumbersome with plenty of room for error.

[@whiplashmachine]

That was pretty simple really.

[@SOLDOZER]

There is but the price of the tool is absurd for the home DIY guy building one engine.

[@ashmanproductions]

The way you're describing that cylinder board gauge with left and right is absolutely wrong and you should not teach people that way cuz the moment you use an interrapid indicator it is a reverse swing in the dial actually swings counterclockwise so this is an inaccurate way to teach people they should look at the plus and minus symbol and you should focus on that and not the particulars of your particular indicator you'll teach them wrong if they have an indicator that swings counterclockwise. Just teaching bad habits!!!

[@SOLDOZER]

He knows how to use the tool but clearly has no experience building engines....at all.

[@ralfsautomotive]

So not how you use a snap gauge 🤣😂🤣😂🤣😂

[@billhenry7833]

What a terrible way to do this. Read autka_me comment below.

[@53_ford_custom15]

First

[@dennisgriffith3741]

I did t understand anything you were talking about. I’ll keep searching I have a 2 stroke cylinder I have to find the I.d dimensions and this video did not help. Maybe I need a more beginning video