dpuma8 Posted March 29, 2011 Share Posted March 29, 2011 I am a bit confused and this is my first build ever. I recently got a Neiko digital caliper from amazon so I tried it out by measuring my pistons and cylinder bore of my block. The cylinder bore for all 6 cylinders was about 90.2mm and the cylinder itself was about 86mm. When I try to fit the cylinder into the bore, it fits snugly. So does this sound like I need a new block or is my caliper no good according to my description? I will put up a youtube video tomorrow Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted March 29, 2011 Share Posted March 29, 2011 (edited) Bores need to be measured with a micrometer and/or expansion gauges, while using proper technique. Most calipers cant do a good job of measuring ID. There can also be discrepancies between the ID and OD calibration of the caliper. Definitely need to be validated, and use a micrometer for critical measurements. Also check for roundness of the bores and pistons. http://www.youtube.com/watch?v=jFeCpDbOpjQ Edited March 29, 2011 by cygnusx1 Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 30, 2011 Share Posted March 30, 2011 Are we calling the piston the cylinder? As bore and cylinder are the same thing...normally. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted March 31, 2011 Share Posted March 31, 2011 Yes, and no. Quote Link to comment Share on other sites More sharing options...
PalmettoZ Posted March 31, 2011 Share Posted March 31, 2011 Hey Dpuma8- Tony's correct, what your saying doesn't make sense. You can't fit a cylinder into a bore. Maybe what you wrote is a typo and you meant to type piston?? Also where you measure the piston is important, because it is not the same at the top as it is at the bottom. I would suggest taking the calipers to a machine shop with your parts and asking them to show you how to use it. Also they should have a "master" piece of some time that has a known demension that you can check and verify your caliper with. Perhaps you are misreading your gauge, not possible to have a snug fit with a 86mm piston in a 90.2 cylinder bore. Scott 1 Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted March 31, 2011 Share Posted March 31, 2011 (edited) Some people call pistons, cylinders. Might have something to do with the cylindrical shape? Get over it. His calipers are out of whack, and he shouldn't be using them for what he's doing anyhow. My engine has 6 cylinders, or does it have six bores...or does it really matter. Edited March 31, 2011 by cygnusx1 Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 1, 2011 Share Posted April 1, 2011 Some people call pistons, cylinders. I've NEVER, since becoming involved in Internal Combustion Engine Work in the early 1970's, hears ANYBODY refer to pistons as cylinders. EVER. Cylinders and Bores...yes. Cylinders and Jugs...yes. Cylinders and Pistons? No. There is nothing wrong with using calipers to measure pistons, OR cylinders at the top---if it tapers that much (and remember we're talking L-Series Block here...) it's toast anyway. Whatever you measure at the top will for all intents and purposes be what you have at the bottom. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted April 2, 2011 Share Posted April 2, 2011 (edited) It is difficult to get an accurate measurement of a bore directly, with a basic $10 caliper. Yes, it can work but it's not the proper tool for measuring bores accurately. Especially if it was purchased cheap, and probably not properly calibrated or built to any tight standards. The ID and OD sides of the tool might not even jive with each other, I am willing to bet. Digital does not equate to precise. He should not go spewing the numbers he is reading to a machine shop, based on what he has measured with his calipers. Or should we tell him to just go with those numbers, they're fine. bore measuring tools http://www.google.co...i=g-m1&aql=&oq= At a minimum, use these: http://rover.ebay.co..._categ_id=12576 Edited April 2, 2011 by cygnusx1 Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 3, 2011 Share Posted April 3, 2011 (edited) Wow, all those years carrying a caliper into the junkyard for identifying parts was useless and I should have been using a Starett Dial Bore Gauge all along. Oh, BTW, how do you know what range standards to install into the precision dial bore gauge to determine those cylinder measurements??? Oh, let me guess, you 'eyeball it' and then select one of the 6 mics in the Inside Mic set to check it... See where I'm going with this? I don't know of any shop that doesn't have at least a 6" Caliper on hand for the myriad quick measurements you need to do every day in a machine shop that doesn't require accuracy to 0.0005" And that is what we're talking about here. This isn't a problem with the tool he's using, it's a problem with if he even knows what he's measuring in the first place. Frankly, for novices, I think the cheap digital calipers is a GREAT tool to buy. As long as they learn to zero it wit hthe jaws closed before measuring whatever, they will be FAR more accurate than using a tape measure, or comparable dial gauge, micrometer, or other tool that requires training and skill to read properly and use accurately. 4MM is not a jaw misalignment issue. This is a 'what the hell did he measure to come up with that?' issue. I might add that the "T-Gauges" aren't marked with size, you will need something else to measure them when it's out...like a digital caliper! The prior comment on the measurement of the bore top being for all intents and purposes the same as the bottom still stands. You can do an I.D. with the caliper, or an O.D. and compare...but for rough approximation closer than 90.5 versus 86mm you can do that with a caliper. I'm betting money he measured the I.D. of the Head Gasket Fire Ring and not a cylinder bore. But he hasn't weighed in since...so this is another troll-post I guess. No you-tube video, nothing.... Edited April 3, 2011 by Tony D Quote Link to comment Share on other sites More sharing options...
bruce83 Posted April 3, 2011 Share Posted April 3, 2011 Tony is always right, but sometimes a little wrong. When I rebuilt my L28, I used an expanding T-gauge to check all the cylinder bores and found that yes the tops & bottoms were about the same size, but the centers were larger. Then when I took the block into get honed (with a torque plate), the guy told my it was normal, as this were the pistons put the must force on cylinder walls, when the connecting rods moved on and off center. Now on to calipers. The most important thing to do before zeroing any caliper is to wipe off the jaws with your fingers first. This is because if there is dirt on the jaws, you are zeroing the dirt, not caliper's bare jaws. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted April 3, 2011 Share Posted April 3, 2011 But when you measure the expanders with a caliper, you are using the same side of the caliper that you used to measure the piston. The "ID" side of cheap calipers is highly suspect. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 3, 2011 Share Posted April 3, 2011 So Bruce, uh... you're saying that for 90.5-86=4.5mm this would not be noticable on even a pocket slide caliper with NO digital readout and just straight lines???? C'mon here---There is ABSOLUTELY nothing wrong with a caliper. And if the inferrence is that 4.5mm difference between ID and OD measuring surfaces is something that is remotely possible....I say HOGWASH! The reason DIGITAL calipers are prefereable over any other type is PRECISELY because you can ZERO the caliper from the ORIGIN position. That makes any 'ID/OD' discrepancy IRRELEVANT. The standard is distance from origin point. If this was a fixed caliper like I used for oh-so-many-years identifying junkyard parts improperly (it was a cheap Brown and Sharpe) without the ability to zero origin, I'd agree there could be a 'drift'... But 4.5 mm ? C'MON! How does someone say that? Take all the ad hominem shots you want at me, but some reasonable common sense needs to come into play here. And I reiterate that 'for all intents and purposes' the number you get at the top will be a REPRESENTATIVE NUMBER to compare against the piston for purposes of 'comparing compatibility'... Bruce, what were your cylinders out? 4, 5, 10 thou? Or less? On an F54 block no doubt. 10 thou is not 4.5 mm. For that, a caliper...shite your EYES can discern that differential. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted April 3, 2011 Share Posted April 3, 2011 (edited) Most of the error, when measuring ID with calipers comes from the user. It's a bit tricky to get the caliper directly across the diameter. Any skewing and the reading comes in short or long. When measuring OD, you have much less room for user error. That's also the advantage of using bore gauges or expanders. I agree, for a quick estimate to 2 decimal places, with a competent user, they work fine. You are rolling the dice when you go for that third decimal. The fourth decimal, using the ID side, is a bit of a joke, when doing true precision work. Measure it three or four times and see what you get. Edited April 3, 2011 by cygnusx1 Quote Link to comment Share on other sites More sharing options...
(goldfish) Posted April 4, 2011 Share Posted April 4, 2011 Even the cheapest calipers are close enough in all 4 directions, that they work better than fine for this. Bruce was pointing out that checking the middle for wear is ideal, as that is where most of it was happening in his block. That maybe just testing the top and bottom was less than ideal. I'm pretty certain Bruce has no problems with calipers. BTW, Bruce, when do I get to see that ZX of yours? Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted April 4, 2011 Share Posted April 4, 2011 I am a bit confused and this is my first build ever. I recently got a Neiko digital caliper from amazon so I tried it out by measuring my pistons and cylinder bore of my block. The cylinder bore for all 6 cylinders was about 90.2mm and the cylinder itself was about 86mm. When I try to fit the cylinder into the bore, it fits snugly. So does this sound like I need a new block or is my caliper no good according to my description? I will put up a youtube video tomorrow I don't doubt that Bruce knows how to use calipers, but when you read the OP, you get some doubts about their proper use, and some questions about the context in which they were used. No? They were probably used wrong here, so we try to point him in the right direction. I guess he left. Maybe that was the right direction. I think I am going to UN-subscribe to this post myself. I speak from experience, my experience. Here are others. Bear in mind the OP is using a pair of $10 calipers for his first time and wondering why the numbers are off. http://mikes-models.com/blog/index.php/2008/09/how-acurate-is-acurate-digital-calipers-versus-old-micrometers/ http://www.homemodelenginemachinist.com/index.php?topic=4430.10;wap2 http://forums.pelicanparts.com/porsche-911-technical-forum/33917-micrometer-vs-caliper.html http://www.practicalmachinist.com/vb/general-archive/micrometers-vs-dial-calipers-92101/index2.html enough. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 4, 2011 Share Posted April 4, 2011 I don't doubt that Bruce knows how to use calipers, but when you read the OP, you get some doubts about their proper use, and some questions about the context in which they were used. No? They were probably used wrong here, so we try to point him in the right direction. I guess he left. Maybe that was the right direction. I think I am going to UN-subscribe to this post myself. I speak from experience, my experience. Here are others. Bear in mind the OP is using a pair of $10 calipers for his first time and wondering why the numbers are off. I agree. Likely he needs some instruction on what exactly to call things, as well as measure them. Like I posited, perhaps he measured the fire-ring on the head gasket given the terminology and massive discrepancy. I don't see even a $10 pair of digital calipers being off this much. I use them for work on machines twisting 54K and they are 'close enough' for non-critical measurements. The OP was not checking his bore for suitability for re-ring or what oversize bore to tell the machinist. He was trying to measure it against the pistons (I think) that he had, which he said 'fit snug'... With a 4.5mm discrepancy as stated by others, I doubt seriously this is a correct reading. Unfortunately as so often happens, someone comes in drops the hand grenade, and then runs off leaving us all with our members flacid and swinging in the wind... This was an exercise in futility as the OP has abdicated his responsibilities after asking for assistance. Can we ask moderators to give guys who do this 'onetime troll' signatures until they redeem themselves in later posts??? Quote Link to comment Share on other sites More sharing options...
dpuma8 Posted April 5, 2011 Author Share Posted April 5, 2011 (edited) Wow. I am feeling really embarrassed right now and am not a troll. This is pretty much my first attempt at really anything like rebuilding an engine. I live in a small town where I don't know anyone to help me and I didn't have a dad who could teach me these cool things. I really enjoy trying to do this (please don't tell me to not attempt this) but I ask a ton of really retarded questions like this. I wish there was a beginner forum for inexperienced guys like me who don't have the knowledge that everyone else has. I just added a video on YouTube but it still says it needs processing. I will post it as soon as it uploads. Edited April 5, 2011 by dpuma8 Quote Link to comment Share on other sites More sharing options...
dpuma8 Posted April 5, 2011 Author Share Posted April 5, 2011 Sorry for the bad quality but it is hard trying to film with an iPhone and work the caliper http://www.youtube.com/watch?v=jScuQQssWLo Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted April 5, 2011 Share Posted April 5, 2011 You need to practice using the Vernier. You measurements are off, most likely due to your technique. I don't have the time to explain right now but I will try to find a tutorial and post it later. Meanwhile practice measuring stuff, at least until you can get consistent numbers from the same part. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 5, 2011 Share Posted April 5, 2011 ???? One: The place you measured the pistons wasn't correct, and you should use calipers with longer arms so you can do a diametrical reading. My internet time is metered now, and I don't have the time to detail the issues I saw in the video. Did those pistons come out of the block you have there? And was the piston you measured out of that bore? Are all the bores the same size? What does common sense tell you about your readings? Quote Link to comment Share on other sites More sharing options...
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