Generation IV Internal Engine - How to measure bearing clearances
07-15-2012, 08:08 PM
I have been thinking about buying an inexpensive bore mic and set of outside micrometers for measuring my rod & main bearings & journals. I also have some plastigage, but I've read mixed reviews on how accurate it is. Would an inexpensive set of measuring tools be adequate for the job? Or are these too inaccurate for this job?
I was thinking this dial bore mic (+/- 0.0005):
And this or similar mic set (+/- 0.0001)
This video demonstrates how to use these
The bore mic accuracy worries me a bit. Would it be better to use a telescoping gauge like the one below, pull it out and measure it with the same mic as the bearing journal?
Any advice is appreciated.
07-15-2012, 09:17 PM
You setup the dial bore gauge with the mic you use for the journal measurements, so the accuracy is quite good as the bore gauge is just an offset from the mic. Get both the bore gauge and the mic set and your all set..
07-15-2012, 09:26 PM
That dial bore gage is just as accurate as a Sunnen, it's all in the technique learning how to use any of them. I have one like it and a Sunnen. Go with the .0001" accuracy instead of the .0005" for doing bearings.
Just buy one micrometer big enough to measure pistons and cranks with all the various attachments for different size stuff.
07-15-2012, 10:06 PM
You really only need one mic a 2 to 3 inch that reads in .0001 graduates
07-16-2012, 07:30 AM
as stated, the technique is critical. Once you can get repeatable measurements, you know that you're getting it right.
07-16-2012, 11:32 AM
Go with the .0001" accuracy instead of the .0005" for doing bearings.
I haven't been able to find one near this price range with a .0001" graduation. Do you know of one? Or would I use the same bore gauge and buy a different indicator?
07-16-2012, 11:40 AM
I don't know of any dial bore gauges with .0001" accuracy that are less than $200. anyone know of any?
07-19-2012, 04:21 PM
This seems to be the cheapest thing I can find with better than 0.005. This is the same gauge fitted with digital indicator that reads to .00005 for $120
I think I may give this a try, just need to find a decent mic or two for the crank journals & pistons.
07-19-2012, 07:32 PM
Found mine on ebay. I don't believe the digital gage will work as good as a dial gage. You have to "rock" the needle to calibrate to your micrometer. Part of the technique!
07-20-2012, 12:12 AM
07-20-2012, 11:54 AM
This is a good thread for those beginner thinking about building their own engines. Keep us posted with your findings.
07-20-2012, 01:59 PM
Man, went back to ebay and found a bunch for around $125 that have 0.0001 dial indicators. I would prefer a dial over digital for this application. Like you said you want to rock/tilt and look for the minimum value. Hopefully I can make due with the digital - it does at least have a digital sweep around the top which should act like a dial.
08-06-2012, 01:51 AM
How is that digital gauge working out?
08-06-2012, 03:33 AM
I went with the mitutoyo 511-169 model. it has .001mm resolution (.000039").
The best deal I found was $301 on Amazon. It is a very good quality tool.
08-06-2012, 06:20 AM
Thanks for sharing.