Questions about measuring main/rod bore diameter

[redhot91gt]

Im planning on ordering toyota select fit bearings, and I understand how to get to the correct size and everything. I was just wondering if anyone has any insight on how you measure the main bore diameters? Do you take multiple measurements to see if they are out of round? Do you take a single 12/ 6 o clock measurement? My engine did not have a rodknock or anything, but I want to make sure I get this correct. I measured number 6 and it looked like I was getting two different measurements depending on which way I was holding the dial bore gauge. Maybe .0009 difference.

Any help would be appreciated
-Stu

 

[--Golli]

When I measured mine, I did 12-6, 2-8 and 4-10.
The TSRM states that the maxium out of round allowed is 0.02mm or 0.0008in.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EM&P=83

Good luck!

 

[hvyman]

might want to try practicing getting accurate measurements on something other than your crank to, so you dont scratch it up.

 

[redhot91gt]

When I measured mine, I did 12-6, 2-8 and 4-10.
The TSRM states that the maxium out of round allowed is 0.02mm or 0.0008in.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EM&P=83

Good luck!

Thanks thats what I wanted to know.

might want to try practicing getting accurate measurements on something other than your crank to, so you dont scratch it up.

I have done some measuring with mic's before, and I made sure to be real careful.

 

[dumbo]

Do you have a set of numbers stamped on your oil pan mounting surface?

Example(Mine) 2221222 (Machinest is taking care of what I think is a FUCKING shitty setup by Toyota!)

Personally not sure what they mean, but I know IJ does and I'm sure others. Has to do with the bore size.

 

[redhot91gt]

Do you have a set of numbers stamped on your oil pan mounting surface?

Example(Mine) 2221222 (Machinest is taking care of what I think is a FUCKING shitty setup by Toyota!)

Personally not sure what they mean, but I know IJ does and I'm sure others. Has to do with the bore size.

Yeah, I have done alot of reading aswell as asked a friend that just went through this with his engine. Its a little complicated at first, but I got the hang of it. Really Im not going off the number I have stamped on the block, because that is when the block was brand new and I am sure they have changed a little bit, as my measurements have shown actually. I will double and triple check my numbers then order them and then check them again, just to make sure all the clearances are perfect.

 

[hvyman]

also use plastigauge(sp) to triple check your clearances.

 

[dumbo]

Yeah, I have done alot of reading aswell as asked a friend that just went through this with his engine. Its a little complicated at first, but I got the hang of it. Really Im not going off the number I have stamped on the block, because that is when the block was brand new and I am sure they have changed a little bit, as my measurements have shown actually. I will double and triple check my numbers then order them and then check them again, just to make sure all the clearances are perfect.

So you plan on ordering select fit bearings(even though you think the bores have changed over time), so you must know what the numbers mean exactly? How are the select fit bearings measured? Honestly it just seems totally retarded to me, why not have measured bearing both ID and OD. Maybe I'm missing something.

 

[redhot91gt]

So you plan on ordering select fit bearings(even though you think the bores have changed over time), so you must know what the numbers mean exactly? How are the select fit bearings measured? Honestly it just seems totally retarded to me, why not have measured bearing both ID and OD. Maybe I'm missing something.

There is a chart in the tsrm that shows the exact thickness of each bearing. Theres 5 to choose from. So I am calculating everything and making sure all my clearances are within the tsrm spec .0012-.0019 (hopefully this is the correct way to do this). They have changed slightly but not enough to be out of spec with the right bearings. I am also making sure they arnt out of out of spec as far as out of round is concerned, and I have one main bore that is close to out of spec but not quite. It was about .0006 (.0008 max), but the rest are pretty dead on.

Also I'll use some plastigauge afterwards aswell, but I was told it is more accurate with bore gauges and mic's anyway.

ps. I dont like the way they are select fit, but its the way it was done and I have to deal with it
Thanks

 

[suprarx7nut]

So you plan on ordering select fit bearings(even though you think the bores have changed over time), so you must know what the numbers mean exactly? How are the select fit bearings measured? Honestly it just seems totally retarded to me, why not have measured bearing both ID and OD. Maybe I'm missing something.

The select fit system takes into account the ID and OD. I'm not sure why you hate the system so much. :biglaugh:

It's not that complicated, but damn some people seem to think it's evil rocket science or something.

You have one number for the OD, then one for the ID. Add them together to "select fit" number. Ensures the bearings fit just right.

 

[suprarich]

If your bearing housing bores are out of round it is time for a line bore. After that they will all be the same size. The crank should be re-polished at minimum, if still well enough to not need re-ground to the next undersize. At that point, you would well on your way to just needing an aftermarket set of "one size" bearings.

 

[black89t]

There is a chart in the tsrm that shows the exact thickness of each bearing. Theres 5 to choose from. So I am calculating everything and making sure all my clearances are within the tsrm spec .0012-.0019 (hopefully this is the correct way to do this). They have changed slightly but not enough to be out of spec with the right bearings. I am also making sure they arnt out of out of spec as far as out of round is concerned, and I have one main bore that is close to out of spec but not quite. It was about .0006 (.0008 max), but the rest are pretty dead on.

Also I'll use some plastigauge afterwards aswell, but I was told it is more accurate with bore gauges and mic's anyway.

ps. I dont like the way they are select fit, but its the way it was done and I have to deal with it
Thanks

^dude if you didn't noticed the select fit bearings for the rods only vary .0009 and the mains .0006. thats not even a solid thousands of an inch. so really they aren't going to make up for much wear. that assuming you had a 1 in all of them. when really most of the 7m's i have torn down have 2's or 3's in there. if i were you i would put 5's in there unless you have a rod pin thats a 0 to make the clearances tight as possible.