Cant remember the math when computing bearing clearance using a dial bore gauge. must be getting old. The crank measures 2.199" and the bearing in the rod measures 2.202" using a snap gauge. I know this would give me .003" clearance, but how do you do the math for the bore gauge? I did 0 the bore gauge in the mic after measuring the rod journal and measured the bearing, but the math make no sense to me at the moment. Thanks

Set the outside mike at 2.2000 and set the dial bore gauge at .0000, then measure the I.D. of the rod bearing with the dail bore gauge and see if it shows on the - (minus) or + (plus )side of the zero. If it is on the plus side add that to the 2.2000, if on the minus side subtract it Let us know what you find out.
BTW, I like the old simple methods also to back up what you find with the new tools

ok, but why set the mic to 2.200 when the journal measures 2.199?

You can set it wherever you want , I used the 2.220 crankshaft rod journal diameter to use as a reference that way when the dial bore gauge reads +.0016 you know the bearing I.D. is 2.2016 If you set the dial bore gauge so 2.1990 is zero and you end up with +.0026 on the dial bore gauge you know you have .0026 bearing clearances, same results using a difference base to sart with, your choice IHTHs

ok, with mic set at 2.199. I pickup the dial bore gauge up and 0 the dial, then I inserted the bore gauge into the mic and it reads .027. I then 0 bore gauge again while in mic, remove bore gauge from mic and insert bore gauge into rod with bearing. bore gauge reads .026. so my bearing clearance is .026?

Dave is it .0026" instead of .026"?

I used the same method on my last two engines. I set the mic on each journal, then zeroed the bore mic and took the measurement.

sorry for the confusion here but i'm not sure. the gauge has increments of .0001. the gauge had .050 written on dial and goes to 10 and therefore every sweep would be .010. every number represents .001. i'm getting 2 full sweeps+ the 26, so if I read this right that would be .026. i'm thinking there should be some math here somewhere to get the end result.

You don't need two full sweeps to get the clearance.

Measure the crank. Set the bore gauge to the mic with one sweep and zero the gauge. Then stick in the rod 90* to the parting line and measure it. What it says is what it is.

the reason for 2 sweeps is I don't seem to have the correct anvil

what i'm measuring is .006 clearance. something isn't right with my measuring.

Oh crap you are at the tweener size.

In a pinch, you can use a snap gauge to measure the bore and then mic the snap gauge and do the math. Not as good as a dial bore gauge but it would get you in the ball park. You could then try and nail it down from there.

Look at the gauge again and see if it says .0005 instead of .050. If it is .0005 instead of .0001 then it reads like my Sunnen gauge does in 1/2 thousand increments instead of one thousands or one ten thousands increments like my Mitiyo gauge reads. I'm having a issue now with my 4 to 5 inch outside mike, it is reading about .0008 to small(SWAG,eye balling it) when I set it up with the 4 inch standard I don't see anyway to adjust and correct that mike so I may end up having to buy another 4 to 5 inch oudside mike. I don't use my Sunnen set up gauge to zero my dial bore gauges due to not trusting it

bore gauge does read on + side of 0 when inserted in rod bearing. Reads .0061, so either im reading gauge wrong or its inaccurate. Meatured bearig again with snap gauge and get 2.202 and rod jounal is 2.199. Ill try a different dial on the bore gauge tomorrow and see what happens.

Dave Do you still have the bore gauge zeroed to 2.199"? If you do set your mic to 2.202 and check the bore gauge again, it should read .003".

Can you post a photo of the dial on the bore gauge?

So you get three with a snap gauge and six one with a dial bot gauge?? Hmmmm. I'm more comfortable with your numbers from the snap gauge right now.


Weird.

me too. I believe every sweep of the needle is .010. The gauge says .050 range. If every sweep is .050 than i have about .003 with the bore gauge.

If it's a 0-.050" then the numbers on the dial face should be half the value shown.

What don't you have the correct anvil for? If it's the dial bore gauge how are you using it?

This gauge is reading in one thousands increments, not .0005, every has mark in between the big numbers is suppose to be one thousands, .0010. So one full sweep from zero to zero would be .100, one tenth of a inch. Me thanks something is not right here, some how
EDITED, it does say on the face that it is measuring in .0001,(ten thousands) not .0010(one thousands) increments The 0050 to .0050 saying would be one half, straight down, of the gauge reading from zero
No wonder your having the problems you are having
Stick with it, you will whup it
2nd edit.I would post pictures of my three different dial indicators reading in .0010, .0005 and .0001 if I knew how now ,but I don't anymore Sorry!

thats where my confusion is at. Increments of .0001, so there is 100 of those on the dial. That would be .010 per sweep. To me every number would represents .001. So where i 0 the bore gauge in the mic and insert it into rod bearing i read .0061 on the dial.

the mic is set to the rod journal diameter which is 2.199. Im using the next to smallest anvil. I only get .004 needle movement using smallest avil with all the spacers. I think the next anvil up gets me truer readings.