What do you guys use? A dial indicator type bore gauge? If so, which brand/type do you use?

Any other tool that can be used that may be cheaper, but have the same results?

dial bore gauge on the housing, and a mic on the crank, to double check the bearing thickness i use a mic.
to do a quick and easy double check on the clearances i plastigage it as well.

Sunnen dial bore guage, and starret mics.

I agree with Brian completely.
Mic the crank and bearing thickness, dial bore
gage on the saddles.

How accurate is plastigage?

Who uses it?

Plasigage is nowhere as accurate as dial bore and mics, but it is a good accurate check if you do not have mics.
When checking bearing thickness, be sure to use a mic that has a radius anvil (I use a Fowler), otherwise your readings will not be accurate. Also remember that the bearing thickness will not be consistant at all locations, this is because the bearings are designed to have some eccentricity and the eccentricity is more pronounced on some designs that others. In other words, a Clevite 'P' bearing will have different wall thickness than an 'H' bearing for the same application.

Anyone know where can one get a decent set of mics and a dial boare gauge, for a fair price?

Dial Bore Gauge: http://www.etoolcart.com/index.asp?PageAction=VIEWPROD&ProdID=5220

Micrometer: http://shoptoolsshoptools.com/shopdisplayproducts.asp?id=211&cat=Precision

Make sure you get a 2"-3" outside micrometer for measuring your main journals.

Originally posted by Fried_Guy:
Dial Bore Gauge: http://www.etoolcart.com/index.asp?PageAction=VIEWPROD&ProdID=5220

Or you can buy a nice Sunnen dial bore gauge for the fair price of around $1000 :D ..........but well well worth it if you build alot of engines..

We had someone come into the shop a few weeks ago with a Sunnen dial bore gauge that he was looking to sell. His asking price - $30 :eek:

Needless to say, my boss bought it - and it works just as good as our other sunnen graemlins/thumbsup.gif

Thanks for all the advice.

We had someone come into the shop a few weeks ago with a Sunnen dial bore gauge that he was looking to sell. His asking price - $30

Did you burn your hands when you touched it? :D

plastigage is a nice sanity check. most people totally overestimate what they are doing when they measure diametrical clearances with a bore gage and a mic. those instruments are not capable of actually checking the "effective" diameters of either male or female components of the clearance. they are point to point and can not take concentricty or comparative roundness into account. dont get me wrong i am not saying that they are not adequate, they are okay in this application, mechanics have used them for years and they get the job done fine. but there is no substitute for a good functional check. plastigage is indicating the real world gap between the two surfaces, not a theoretical gap you get by comparing two diameters without respect to actual centerline concentricity or effective diameters.

Originally posted by 79943:
plastigage is a nice sanity check. most people totally overestimate what they are doing when they measure diametrical clearances with a bore gage and a mic. those instruments are not capable of actually checking the "effective" diameters of either male or female components of the clearance. they are point to point and can not take concentricty or comparative roundness into account. dont get me wrong i am not saying that they are not adequate, they are okay in this application, mechanics have used them for years and they get the job done fine. but there is no substitute for a good functional check. plastigage is indicating the real world gap between the two surfaces, not a theoretical gap you get by comparing two diameters without respect to actual centerline concentricity or effective diameters. =
Huh???
While I will agree with your first statement I completely disagree with the rest.

Lot's of neat big words but I fail to understand what it is you are trying to convey :confused:

How exactly does plastigage have anything to do with measuring concentricity, or comparative roundness or have anything to do with the centerline?

First off, the crank journal is the only round part we are measuring, the bearing is not a round hole.
And even though I calibrate my mikes every day & almost everytime I use them in the summer when the weather changes, even if your mikes are not correct it will make no difference if you use it as a setting standard for the bore gauge which is all you need for an extremely accurate clearance check.

Plastigage is a pretty good check when you do not have the correct equipment and is an excellent "double-check" as Brian uses it just to be sure you have somewhere near the clearance you want but even the makers of Plastigage would never consider telling you it is more accurate than a quality bore gauge & set of mikes.

Just for info, standard bore gauges tend to gouge the soft bearing surfaces but Mitutoyo makes one with a large radius tip that will not damage the bearings that I use. It ain't cheap but is the right tool for the job ;)

Just my opinions from doin this for about 40 years ;)

Originally posted by Wolfplace:
0q [/qb]=
Huh???
While I will agree with your first statement I completely disagree with the rest.

Lot's of neat big words but I fail to understand what it is you are trying to convey :confused:

How exactly does plastigage have anything to do with measuring concentricity, or comparative roundness or have anything to do with the centerline?


Just my opinions from doin this for about 40 years ;) [/QB][/QUOTE]

plalstigage doesnt have anything to do with measuring conentricity or comparative roundness, it does indicate the "effect" of those on actual clearance. measuring the main bearings individually on a crank does not account for their common centerline, or lack of common centerline. when a crank is nested in the saddles any difference in a common centerline of the journals (and there will be some difference) will immediatley transfer to concentricity error with the saddle centerline and that will effect the gap. obviously too much concentricity error would lead to binding and you would have to align hone to correct it. i am talking about error that is not that extreme but still has an effect on clearance. this would be evident in plastigage that was compressed more on one side of the journal than the other. now this wouldnt be nearly as much a problem in rod bearings because their centerlines are completely independent, the crank journals are not.

I'm with Mike.
I also own a machine shop, have 20 years experience, and own all the proper inspection
tools. The tolerance of the crank grinding should
be well below the resolution of the plastigage
check. If my crank were more than a couple ten
thousandth's out of round, it would get more
work. Mechanically checking the crank,bearing thickness, and saddle dia. is the most accurate
method I know to check clearances. The rest is a
matter of resolution, and we can inspect down to
.0001" with pretty good confidence. :cool:

Originally posted by Wolfplace:
=
Huh???
While I will agree with your first statement I completely disagree with the rest.

Lot's of neat big words but I fail to understand what it is you are trying to convey :confused:

How exactly does plastigage have anything to do with measuring concentricity, or comparative roundness or have anything to do with the centerline?


Just my opinions from doin this for about 40 years ;) Originally posted by 79943:
plalstigage doesnt have anything to do with measuring conentricity or comparative roundness, it does indicate the "effect" of those on actual clearance. measuring the main bearings individually on a crank does not account for their common centerline, or lack of common centerline. when a crank is nested in the saddles any difference in a common centerline of the journals (and there will be some difference) will immediatley transfer to concentricity error with the saddle centerline and that will effect the gap. obviously too much concentricity error would lead to binding and you would have to align hone to correct it. i am talking about error that is not that extreme but still has an effect on clearance. this would be evident in plastigage that was compressed more on one side of the journal than the other. now this wouldnt be nearly as much a problem in rod bearings because their centerlines are completely independent, the crank journals are not.

=
I am assuming you are referring to one edge of the bearing journal to the other rather than opposing sides as Plastigage is not used on both sides of the journal, it is used on a dry crank & bearing & only on one side & measures the approximate total bearing clearance.
In this case I see what you are referring to but in reality you will find that unless there is an extreme "bend" in the crank or main bores this will very probably not show up with Plastigage.

The crank is a lot more "flexible" than most people realize & if it had enough "bend" or the main bores had enough misalignment to effect the Plastigage you will find in the real world it will not turn freely in the bearings when you assemble it.

Plastigage is not considered an accurate measurement but is close & better than not checking.
It can only be used on the top side of the part in question unless you support the part or the weight of the part will effect the width of the Plastigage.

You are supposed to check the crank & main bores for straightness & taper before you ever check the clearance, not while measuring clearance if this is what you are referring to by concentricity error & centerline.
You are not supposed to just measure the center of the journal & assume it doesn't have taper.

Also, if the crank or the main bores are out of alignment enough to effect the operation of the engine the crank will bind when rotating.

Again, Plastigage is a reasonable alternative if you do not have the correct tools but is not considered an accurate measurement compared to a good bore gauge & set of mikes used as a setting standard for the bore gauge.

Not trying to be argumentative here but this is not just my opinion. It is the opinion of every good machinist (& even some not so good :D )
that I know & probably most I don't know.

And again, I think you will find even the people who make Plastigage wouldn't consider telling you it is as accurate as using the proper equipment.

plastic gauge will give you a crush reading in thousnads wich is important to bearing play if its to loose then a you have the wrong bearings or b you need to resize your journals or rods to acheieve optimium clearnace for proper bearing wear and steady oiling.. never seen anyone check torque crush clearences with a caliper or a bore gauge.. plastic gauge is cheap and is relatively on the money . if your not sure how to use it BUY book ..

Plastigage won't tell you if your bores are egg shaped. I checked the clearance (with bore gages and a mic) after an align bore of a 454 with severe oil pressure problems. Somehow the align bore process went bad, and the guy ended up with clearance from .0025" to .0055" . Using plastigage would have shown the clearance as ideal at .0025" "up and down" but the rest of the bore was wild.

I have a winter project which has just started, building a 454 BB. So far I have the block and the crank. When i get to that stage I will probably borrow some gaging from work that will check the clearance to 50 millionths (being a QC Manager has its benefits). But after I do that I will drop plastigage on at least a couple of bearings as a real world check. Now if that plastigage bareley flattens or if it smears out I am not going to believe the numbers I got with the gaging no matter how accurate it is. Because I may have made a math error, measuring error, or I may have an alignment situation, but in any case I will stop there and see what is going on. One might just say well the gages I used are more accurate than plastigage so I will just believe the numbers and charge ahead. Not me. 35 years in QC has taught me that functional gaging is the best sanity check you can make, I have seen hundreds of errors from measurement and calculations and only a handful from functional checks. The point is that just to make the assumption, that since one method is potentially more precise than another is missing the point. If its important enough then check it twice and check it with more than one method. I was just trying to make two points when i posted earlier 1) single point linear measurement is not definitive when checking effective diameters (and that remains a fact) and 2) use a nice sanity check whenever possible because it will help find gross errors and it will help you understand what is actually taking place in the machine and assembly work. JMHO from 35 years in measuring things for airplanes and missiles and cars on the weekends.

Hey,, this sure beats watchin TV :D

If you read my first post, I completely agreed with using Plastigage as a "sanity check"

What I did not agree with is the implication that it is as or more accurate than the proper equipment.

And I also completely agree that there can be Math errors,,,, I make enough of them myself which is one of the reasons I normally double check almost everything I do.

Again to be clear, what I am saying is if you measure the OD of the journal with X set of Mikes & then use this set of Mikes as a setting standard for the bore gauge you are using it is a very accurate measurement of the difference regardless of weather the Mikes in question are even accurate as all you are doing is using them as a setting standard for a comparative measurement not as an exact sizing measurement for the journal in question.

BTW, This is not an endorsement for not setting your Mikes daily to actually check the size of whatever you might be measuring graemlins/sad.gif

It just an example of how to get a very accurate clearance measurement within the boundaries of the equipment we are using which is in most cases in tenths & at best at least in my case in half tenths which is really academic as I am not in a climate controlled environment as you probably are.

All that said,,,, Man but I would love to be able to play with some of the equipment you have access to ;)

Again to be very clear,,, I am completely agreeing that Plastigage is an excellent "sanity check" & is a viable alternative when you do not have the correct equipment & that math errors can be a problem & that you should never assume one measurement is correct.

I am in disagreement with Plastigage being as accurate as using the proper equipment. ;)

Aw crap,,, lets just use a ruler :D

Originally posted by Wolfplace:

Again to be clear, what I am saying is if you measure the OD of the journal with X set of Mikes & then use this set of Mikes as a setting standard for the bore gauge you are using it is a very accurate measurement of the difference regardless of weather the Mikes in question are even accurate as all you are doing is using them as a setting standard for a comparative measurement not as an exact sizing measurement for the journal in question.


I am in disagreement with Plastigage being as accurate as using the proper equipment.

[/QB]What he said graemlins/thumbsup.gif

OK, I will chime in here as a voice from the manufacturers of Plastigage. We do not feel that Plastigage is as accurate as mechanical measuring devices, such as bore gauge and micrometers, and we have never made such claims. Plastigage is marketed as a backup clearance checking device. It is commonly used by people who do not have access to mechanical measuring tools and also as a comparison analysis by people who have checked the clearance by mechanical means.

Plastigage is extremely accurate (if used correctly) and it is used not only in the automotive industry, but also in machine tool, aerospace and many other industries as well.

Like Mike stated above, the effective success of measuring with mechanical devices is dependent upon the accuracy of the tools, the temperature of the surroundings as well as the parts being measured and finally the skill of the person taking the measurements. (Believe it or not, I once witnessed a "professional?" mechanic using a micrometer as a C-clamp!)

Plastic guage does have a shelf life so buy new whenever you build an engine. I have some that shrunk and turned brittle with age. If the stuff shrinks it will change your width/crush measurements during use. Throw the old stuff away and always use fresh. I noticed this with the last motor, old plastic guage readings vs. new were way different!

If you you have a competent machienest that checks everything there's never a need to use plastigauge.

"If you you have a competent machienest that checks everything there's never a need to use plastigauge."

He who thinks this has no business even thinking about assembling an engine. Every human being can make a mistake. Heck, I bet that Mike has even made one :D The guy that grinds our crankshafts for us is probably one of the best there is, and I have never found a single problem with a crankshaft he has done for us BUT ... I still check each and every one. The engine builder is responsible for checking all of the parts that go into the engine. If you are not willing or able to do this, then you should not be assembling an engine. I think I do as good a job on machining as anyone, but I would never tell someone to not check behind me.
Just my opinion,

Originally posted by BillK:
"If you you have a competent machienest that checks everything there's never a need to use plastigauge."

He who thinks this has no business even thinking about assembling an engine. Every human being can make a mistake. Heck, I bet that Mike has even made one :D The guy that grinds our crankshafts for us is probably one of the best there is, and I have never found a single problem with a crankshaft he has done for us BUT ... I still check each and every one. The engine builder is responsible for checking all of the parts that go into the engine. If you are not willing or able to do this, then you should not be assembling an engine. I think I do as good a job on machining as anyone, but I would never tell someone to not check behind me.
Just my opinion, =
Haven't made one this week yet but I still got 4 days left :D

Seriously, never assume that we can't make a mistake,,, stuff happens ;)
Always check no matter who does the machining,, even Bill :D

Do you guy's use plastigauge,Wolfe,Bill K.?

"Always check no matter who does the machining,, even Bill "

Should read "especially Bill" smile.gif

BB I have used plastigage a few times as a quick check, but 99% of the time it's the bore gauge.

Originally posted by BB485:
Do you guy's use plastigauge,Wolfe,Bill K.? =
I don't but I highly recommend it if you are assembling your engine & don't have the proper equipment & even if you do it isn't a bad idea for a double check until you are sure you are using the equipment correctly.
As has been stated,, it an excellent "sanity check" ;)