As a quality engineer, I have to make some comments on your measuring techniques. 1. Your micrometer: You should use your reference piece to set it. And this is how it goes: Make sure all surfaces are clean. Tighten your micrometer with your reference piece in between. Read it. If it differs from your reference piece, you lock it, and then use the special wrench given in your kit to adjust it to whatever your reference piece say.

Folks! Where is the love,this chap is helping us lesser knowledged occupants of earth a way to expand our miserably poor mental database,he has taken the time to make this video so please respect this.i am currently stuck in costa rica(not a bad thing),with a dead engine on a old diesel landcruiser,it has just been to the engineers and i am busy checking all his work before assembly,thanks for the video and I will look forward to more!.

I want to thank you Jafro, because i used the video's in this playlist at my Trade school to help explain to the other students in my class how to use these tools. It's a section in the course and they came in very handy and helped me pass my test on the subject of measurement and engine servicing!. My Teacher was very impressed!

This is different than what I've learned. In the past, I was told to set the dial bore gauge to the spec. and any variation from that setting indicates over sized or undersized.

Quick tips. Most decent micrometers can be final calibrated adjusted of the spanner wrenches are included. Also, with budget calipers break off the thumb wheel. It helps with accuracy.

Nicely done. Thank you for the explanation. Your video is one of the few that make sense to me as to how to measure a bore with a dial bore gauge.

You have no clue how much this video helped me understand the Dial Bore Gauge. I have a nice set of 3 that has been in my arsenal for a few years (passed down from my late uncle) . While in school to get my associates in automotive repair I took this set of tools to my teacher to see if we would use them and if he could explain it to me .... Needless to say during the 2 years of class's none of my teachers would explain how this works or show me how to use it (Not even my engine building class , because most "students" can afford this style tool)................ Thank You .... Now I can use one of the best tools in my arsonal ......

Oh damn. I see big things coming. It's a huge commitment. I wish you luck, I just started a video of installing a Saturn 105 amp Alternator in a DSM. I got about to the point where I was shaving little by little to get it to sit flat on the bracket and I stopped recording. Though I have most of the footage complete. I gave up as the car is a DD and needed to be finished. It takes a lot of effort to make these videos. Thanks for your DSM contributions.

Well it was a pretty good video about how the equipment works, but at the very best even Mitutoyo or Starrett will only guarantee there far better dial and digital calipers to around .002". With a lot of experience and double checking yourself with gauge blocks they can usually do a bit better than that if your careful. But the way digital calipers work is the last digit will always be a 0 or 5 since the internals round off the last number unless you get into a couple of the very expensive specialty European brands of digitals that supposedly will do down to .0001". The number of digits to the right of the decimal point is called resolution, or how the tool is numbered. It's actual accuracy is completely different.Setting a bore gauge with any of the 3 types of the more common calipers is pretty much worthless for any dependable accuracy when your trying for .001". Even a top quality .0001" reading micrometer is still only guaranteed to + - one count. The only two common ways most of us would have access to for accurately setting bore gauges would either be by very expensive certified ring gauges, or second best a good set of gauge blocks. Check with any good engine machine shop and they'll say the same. And any good shop will also have those ring gauges for checking and setting there bore gauges. Probably about the very best bore gauges available would be Sunnen with a price to match. Almost everything I've said here can be verified on Starrett's or Mitutoyo's websites with a bit of searching. Measuring reliably to .001" is a whole lot more complicated than it first seems. .Down to 0001" takes an order of magnitude more. As a rough double check on what an engine machine shop did then yes I guess you could figure on being within maybe .005" with the way it's shown here. And I certainly don't mean any of this as being critical of your video. A Google search for metrology, uncertainty of measurement, and the difference between resolution verses accuracy will teach anyone a lot if there interested.

Love your videos! keep making em.

I had a quiz today on micrometers in auto! Weird coincidence, we measured brake rotors, a cylinder on a Honda block, and tons of other random stuff! Well explained and as always great vid!

Thank you so much! Going out to buy my first bore gauge & this was very informative!

Cool. Just learned how to use my new Christmas gifts. Thanks!

I tried to find a digital gauge when I was doing my build and it would have been invaluable, but I had to purchase the Micrometers, Board gauge, and digital calipers all at the same time. Great explanation on how to zero the gauges. It took me hours of searching and reading to figure out what you taught in 10 min. FWIW there is an event (Import shootout) at Virginia Motorsports Park this weekend. Come by if you are around. I will be trying to scratch my way to the winners circle.

Thanks for your videos they inspired me to make some while rebuilding my Datsun 240z motor

thank you, this helps me alot with measurements. you have good teaching skills. any new engine building videos coming?

This looks like the start of an engine building series.. go jafro.. looking forward to it!

Aha finally can message I thank ye for the DSM Motor build knowledge. I soon hope to start restoring my 1989/90 AWD TSi. It's going to take a lot of time. I have a lot panels to replace and a new harness maybe and I would like to go as far as re-installing the factory emissions. Then slowly start adding to it. Kinda like Tom's Project Sleeper but with factory 14b.

Question, when you do a bore/hone you use a torque plate to ensure perfect roundness of the cylinder wall when the engine is all together, my question is should you take the measurements with a torque plate on the engine to check for egg shaped warping or it doesnt matter?

Thank you for this video. It's very resourceful.

Great video. I have that digital caliper and have found it only accurate to only .01".

Jafro its me again. The guy from the clutch adjustment video. Just want to thank you for this one! Could not have come at a better time. My car overheated the other day and boom goes the head gasket. Spark plug wires are melted into the head. So I am assuming the head is gone. I'm going to be ripping it apart soon and checking it out. Just haven't had the time. Cant wait for the next videos!

very informative, useful information! Great to learn from

Using a dial bore gauge like this seems counter productive. This is the more common and more accurate method: Set a micrometer (unless you have a ring gauge or bore gauge calibration tool) to the specification for the bore and clamp it gently in a vise by the frame. Let's say our bore specification is 4". Select the right adapters and shims to get dial bore gauge head length close to that 4" and then place the dial bore gauge into the micrometer set to 4". Rock the bore gauge it to find the centered value, hold it there, and zero the dial bore gauge by turning the face of the gauge so that the zero is under the needle. This zeros the gauge so now when you place it into the cylinder to be checked you have a base reading already and you don't have to do any math. Hope that makes sense. Setting it up the way it is in the video adds steps and more chance of errors. I have never seen anyone do it like that.

Dude, No Homo but i love you! These videos that you're about to make are going to be so educational for me and the rest of the world ! Great Job!

High quality video, Jafro

If i bought one of these can i attach the gauge to a magnetic stand to do other measurements?

Great video! Thank you!

Wow, this was brilliant, just like I was back at college learning my Toolmaking trade. I was always going to make a video like this once upon a time, but never did, I still have all my Mics. One snag, I needed to see the thimble up close to see the graduations on the Mic, I couldn't see them, which means if I was a complete beginner I would struggle a little. Its only my opinion. I love this topic, I could go on... ha ha Great video, 5*

Very helpful thanks man

Dial bore gauge get me confuse than the dail caliper and micrometer. How do i know which guide do i need to use for measuring cylinder? Or do just play with it

I was wondering how you set your dial bore gauge? Do you set it at zero then insert into the cylinder wall and move side to side to get it correct measurment, is this correct? Isn't the dial gauge similar the dail bore gauge?

I have the same exact micrometer set, but I've never figured out what that double sided hook is for? it's the weird piece by the 1" and 2" reference rods. Thanks

Hi jafro, its me again jom. hehehe. have a question, i removed my oil jet squirters (2g) to have it cleaned using ultrasonic method since im having problems looking for a replacement parts here in the Philippines, is there a way to check if its working in a good condition? any specs that i should check? thanks again!!

Mr Jafro, It may be helpful if you post links to where you can buy the products you are featuring in the video's description.

When you measure the probes are you supposed to compress the end piece or is the correct mesurment without the end piece compressed?

I have been told that you can use telescopic gauge to measure inside cylinder wall and measure it with micrometer. I'm not use of using the dail bore gauge. I have dial bore guage and i use it measure the clyinder but sometime i don't know which guide i need to use because all engine block clyinder head have different sizes and sometimes i might measure wrong. Dial bore gauge complicated sometimes..

@Jafromobile Indeed. Even for a refurb autozone alternator. Lifetime warranty you can't beat. The gentleman told me that as long as I kept the alt in good shape after "Machining" it to fit. He could pass it off as a normal one and do a free replacement. Can't beat that.

Excellent video, but suppose I want to check my lifter bore? Those are pretty small and even though that is a good tool I'm pretty sure that it won't fit that small of a bore so is there an alternative?

Good stuff!

one thing i don't get is that i saw in a couple of other videos they said to set the dial bore gauge to the cylinder bore specifikations but you seem to set it a little bit bigger which way is right????

When you going to do a video on the tear down on your motor.

Jesus , its about time, i was wondering if you were still alive! Good video man, look forward to seeing more from you, and id love to see that colt running! I have a question for you, any idea how to get the diagnostic codes out of a 2003 carisma, it should have a 16 pin eodb plug but i cant find it, its a 1.3 petrol engine, 5speed manual, maybe you can shed some light, i would really appreciate it!

when i push that very little buttom type this at the bottom the needle moves

According to what i can the specified spacers of bore gauge

"1.9995 ... welcome to A, A, A, A, A, A, A, A, A" LMAO! I love how you sneak these witty remarks and stuff in some of your videos.. I'll be completely focused on what your explaining and the next thing you know I'm blowing a 1.9995 on a breathalyzer lol. Keep educating me, you have a way of holding my attention.. other videos are dull, boring and drawn out..

looking for a good set of micrometers a middle of the road set any thoughts

2 The caliper: please don't use this for any correct measuring. This is ok to check general tolerances. But when it comes to engines building specs, there's far more precise tools you should use. 3. The bore gauge: setting it should be done with a reference ring (ideally), or with a micrometer. Easiest way is to have the exact same dimension like the bore to measure. Assemble the bore gauge to fit that dimension (as you explained very well)

how do you get a .05 spacer for the bore gauge?

hi and congrats for the very useful video. dear, how could you measure inner diameter or valve guides? i mean for motorbikes, that usually have valve stems from 4.0 to 5.0 mm diameter and valve guide accordingly. are you aware or bore gauges able to measure such tiny diameters? or shoul we use " pass non-pass" calibrated cilinders? thanks again and great video! cheers from italy.

2:30 just idk there reference cant be entirely accurate unless measured at the proper reference temperature aswell (idk usually somewher around ambient temp but yeah weather and all..)

how much travel does the bore gage have? not the dial that it comes with.

Thank you, thank you, thank you....

Temperature. All tools and parts must be at the same temperature around 20°C. they are at the factory and they should in your shop. otherwise you will never have a consistent and accurate measurment. important to remember when you work in a garage or if your parts are stored outside......

this might be a stupid question but if the needle doesn't move around is the bore gauge broke or have a set it wrong

hi, i think the wear is 14 10,000 of an inch not 14 000 of an inch.. please advise it is (3.3474 - 3.3460) gets .0014 . you can see this at 9.58 run tim of ur show. I may be wrong, pls comment. Second to go with digital guage, i assume you just change Dial guage with Digital guage and use same adapter, avnils etc. is that right.

You say it is off 14 thousanth but when I do the math it comes to 3.3474-3.3460= .0014 and thats not 14 thousanth of an inch is it?

You use the telescoping bore gauge, measure it with the micrometer then zero the dial bore gauge in the micrometer and use it for reference to see what the size of the bore is.

hey jaffro, I'm having an issue... so I'm measuring a Subaru ej257, stock bore 99.5 mm= 3.917 inch. I used the 4' extension. I keep getting. 165 as my reading pretty much all the way around, but my math is leading me to 3.9835' which leads to over 101 mm but that can't be right the Max bore is 100 mm... lil help?

I don't get it. How is it that the digital calippers are off if it was the micrometer being off?

Jafro- Usually I agree with you. However The way you accounted for the inaccuracy of the caliper was incorrect. The last digit displayed is always uncertain... So really, with both your calipers and mic's the 0.001 is the uncertain digit. With the dial bore gauge the uncertain number is in the 1 ten thousandths place. Setting up a dial bore gauge with a less precise caliper is not good practice. You should use a micrometer with a similar or finer resolution.

When you order from MSC, go all digital or all mechanical. You will give yourself a headache using both. MSC has the best stuff and I love the Big Blue Book, but when you find what you want, try the part numbers at other places on the internet and you will definitely be able to save some money.

just so you know, @ 3:36, use the very end of the caliper and it will be more accurate. You are supposed to take the measurement from the part with a blade cut in, the other part is not the same.

Now, rock it left to right(so towards tip and back),while giving slight angular adjustments(+ and -) And as we're in a circle right now, and you are looking for your diameter(on that line) You need to look for the the smallest dimension with the rocking lef to right, but the largest with your angular adjustments.(Imagine yourself in a cylinder, and you have to point out the exact diameter). There is no such thing as taking an average for any exact measurement. At a point the gauge will tell you.

One type of system not seen here is the three point bore gauge system as manufactured by Sangha Metrology. See this on

Might want to take another look at those micrometers. The spanner should fit a lock nut and into a small hole on or near your scale. Once the lock nut is loosened, the scale should be able to be rotated. Even my cheap import micrometer can be adjusted. The standards included in your set are used for the 1" and larger micrometers to set to zero using the spanners. If your's cannot be adjusted, then you have a very strange set of micrometers and if it were me, I'd sell them and get something else.

@Jafromobile You can get some cheap used mics at flea markets or ebay. Just get a good brand (I like Starrett), and you should be able to measure to +/- one tenth (that's 0.0001) with out any problem. I guess you could zero it with your mic's and a short probe and just switch in a longer one. Still not ideal, but maybe a little better.

well when i compress the probe the needle is completely still

If I used the same standard to test more than one micrometer for accuracy and found that each mic was off by the same amount I'd suspect the standard - especially if it had been dropped and mishandled as this fellow did right on the tape.

What brand are your micrometers?

mastering your bore gauge off of a silly digi mic was not a good idear... i'm sure it was done for video sake, but snapping the gauge at multiple heights & perpendiculars will give a good idea of taper and roundness!

Nice, how could you do that with inches ....Ce n'est déjà pas si facile en métric, je n'aurais jamais pu utiliser des comparateurs ext ou int avec ces horribles inches perso. Quelle chance d'etre né en france (je plaisante.. ;-) ) Belle explication

nice :D

okay thanks

Did a search on Harbor Freights website and found your micrometer set. One of the reviewers said they don't come with instructions. No wonder. Cen-Tech - Item#66512, right? The reviews mentioned calibrating them using the supplied standards or gauge blocks. Double check for a nut and hole that the spanner fits into. If you send me pics I might be able help you figure it out.

i always fail on bore gauge.. i don't know why my tutor do it look easy..but in my hand, i always get diff result.

@Jafromobile Thanks but i'm not brilliant. i'm just a random dumbass who try to go a bit further. i've visited a machining shop and talked a bit with the cool owner temperature is an important part but often forgotten that' why i made a comment on it (and the winter is coming so...) Happy to know that you have a thermal expansion vid it's very interesting yet. the problem is you don't know as a viewer what it's prepared or what vid will follow.

@Jafromobile I find that I learn faster and better methods and techniques when I experiment and learn on my own. Auto isn't fun for me anymore because just a few people in there work including myself.

It has the wrench to calibrate mic,

Can't you just zero the micrometer? I just did mine by twisting the fixed vernier barrel with the included tool... (Awesome videos BTW!)

Most inexpensive sets are accurate to 0.0005 or five (tenths) a tenth is one tenth of one thousandth of an inch.

It's a shame to zero your most accurate tool to your calipers. Would be nice to have a set of 3-4 mics, but you could measure out the attachments with your mics and add them up. Though that gets messy.

@Jafromobile Aw, you made me feel bad then, i was just kidding with you! Sorry about your technological problems, your poor eclipse included, hope shit starts to look up for you soon!

bought all the tools at harbor freight eh??

Check out MrPete222 Machine Shop Tips Number #21 for further information on how to use a micrometer, including the proper way to zero it.

If both tools measure the same reference at the same .0005 perhaps your reference is the thing that is off.

hey ya back :) i got a new vid you should see

not to whip a dead horse here but your wear was .0014 which is fourteen tenths of a thousandth of and inch, not 14 thou (.014)

the minimum reading is not 0,005, the minimum is 0,001 as it says. How ever, this problem what u have discovered means that reading is starting little bit late (or earlier) :)

A digital caliber that is accurate to 0.0005? h, even in inches i dont believe so :D I would more trust the mic

micrometers and vernier cals are easy but i hate bore guages_-_

+SamDearn it's *you're It helps if you're insulting someone's intelligence that you use proper grammar and punctuation. Just for the record, you've been banned.

I can see this is from 9 yrs ago. You do understand your reference for what the graduations are is not correct. .0001 the first number is tenths of a thousandth, 2nd is thousandths, 3rd is tenths, 4th is hundredth, then of course on the left side of decibel would be inches. So you were looking for a bore of 3.7460 & you got 3.3474 that would be 3inches 3hundred & forty-seven thousandths & 4 tenths. Im not trien to be to critical, I just thought it should be clarrified for others that may view & not know.

Dont by cheap measuring stuff guys,sure you CAN get by with some cheaper items but when it comes to measuring i have a no-crap-tools policy! I see SOO many people overpaying for brand new chinese junk it makes me cringe! Cheapest chinese dial caliper on eGay is about $25AUD here, ive seen used Mitutoyo stuff sell as cheap as $15 with my cheapest being $28.10AUD (including shipping!) that are seriously mint inside case with ligth wear on case, im talking older Japanese made stuff without plastic housings as well,i personally steer clear of current production stuff as too much plastic.Why buy chineesium? I not long bought a boxed un-used (NOS)set of 6 Mitutoyo mics with standards for only like $100 more than a chinese set would sell for here,$100 over 6 mics is FUCKALL to pay to go from chinesium to vintage japanese quality. Other stuff i recently got was boxed mitutoyo bore guage(17 to 35mm IIRC) mint condition complete in case all accessories and paperwork, plastic still on id label on the bore gauge extension tube thingy (lol i dont know its name!) i think that was $180 and a boxed NOS depth gauge with all the rods for i think only $120aud. You dont have to spend the earth (prices in my local weaker currency,convert to yours and take into account stuff is generally more expensive here in Australia) if you hunt around.I bought a nice dial indicator from an ebay seller who stocks crazy amount of vintage stuff and threw his card in, all that came from the one guy.

Rather than a bore gage, I just use regular telescoping snap gauges and mic them.

Where to even begin I understand you want to help ppl learn but everything I seen here is wrong a calibrate the mic that's what the supplied wrench and standards are for second calipers are NOT an accurate measurement device use mics to set the bore gauge and set it to zero at the desired measurement and then you check the bore off of that in which once the bore gauged has been set and zeroed for example at let's say 3.5000 inches you angle it into your bore until it reaches the largest number on the dial gauge before it begins to fall back off and that number be it on the zero you set or however far deviated from that is the correct bore measurement sorry to leave a negative comment but this is going to completely screw up people who don't know and if you attempt to do it this way you need to either a look into channels such as abom79 or suburban tool to see the correct way to measure with precision tools or take it to a reputable machine shop to do for you I own my own shop and build and rebuild Harley motors and have seen first hand the devastation on several occasions that can take place because of guys watching a KZfaq video and doing things the wrong way because they wanted to learn and we're misinformed

regarding to ur block gage u have to use two words a thousand or a hundred because u confuse the new learner ,,

Welcome to aaaaaaaa aaaaaaa 😂🤣

Don't use digital precision measuring tools!!!!! If you go to any top nascar engine shop they never use digital measurement tools for engines. Digital angle meters are ok. But when we are measuring oil clearances in the range of 0.0015 to 0.003. An error of 0.0005 is common with digital tools of comparable prices. Google Precision & accuracy.

omg all wrong, look at other videos of how it is done..