Measuring Rod, Main bearing sizes

Justin727 · 12-27-2005, 11:58 PM

hello everyone some of you may know me from sf's, TSF's, sm, i-supra, and some others. But I need help. Measuring Rod and Main bearings... I have a plastigauge. Everything is apart crank has been micropolished and cleaned. Rods are Eagle. Can anyone give me any pointers on how to measure for these sizes. I had everything in order such as the main caps paired with the main bearings but got it all from the machine shop in a big bag instead of the 7 i had. Any help will be greatly appreciated thanks!

TONY! · 12-28-2005, 12:27 AM

If I were to build a motor, I would do it myself.

The hardest thing about building one is knowing how to get the right clearances.

(Many seem to operate on hope.)

The TSRM states what you should have for your clearances.

Now MY procedure would be to:

1) Have one machine shop mic' up the bores and write it down, and give it to me (I did that already).

2) Go to another machine shop and have the bores mic'ed again to verify and double check the numbers. (It is very important to get this right, so a second measure is worth it to me.)

3) Mic’ my outside diameters (journals). Or you can have the shop do that also if you think you won’t get accurate values.

4) Match up the values (ID’s and OD’s) to these charts:

http://www.cygnusx1.net/supra/library/TSRM/em/EM_70.html

http://www.cygnusx1.net/supra/library/TSRM/em/EM_73.html

5) Confirm with Jeff Watson and buy from him.

Measuring outside diameters is pretty easy (crank journals, cam journals, turbine shafts, pistons, valve shims, valve stems, etc).

It is the bores that are extremely hard in comparison (crank tunnels, cam tunnels, turbo cartridges, cylinders, valve guides, etc).

Justin727 · 12-28-2005, 12:31 AM

nicely written Tony! Thank you!

TONY! · 12-28-2005, 12:51 AM

Your welcome.

Just as a mention, as far as I know, the "Select Fit Bearing" system that Toyota uses: that is because of variations in the bores, not the journals, or at least that was my take on it. My crank was perfectly symetrical. The block's main journal bores, however, were all very slightly different. Maybe it is much easier to get an outside diameter uniform than it is to get a series of tunnels one uniform diameter.

To accurately measure the bores, a cylinder gauge is required.
As seen in this pic:
http://www.cygnusx1.net/supra/librar.../em/EM_74.html
The one I seen being used had a water level to ensure that the gauge is perfectly perpendicular to the walls.

Using T-bore gauges will not be accurate enough.
If they do it with a T-bore gauge, I would get nervous.

Hope that helps

Justin727 · 12-28-2005, 01:43 AM

Thank you agian tony you are a valuable asset to the community its a shame we lost you at sm and sf's. Thanks agian for the help Buddy!

12-27-2005, 11:58 PM	#1
Justin727 Stock Join Date: Dec 2005 Posts: 4	Measuring Rod, Main bearing sizes hello everyone some of you may know me from sf's, TSF's, sm, i-supra, and some others. But I need help. Measuring Rod and Main bearings... I have a plastigauge. Everything is apart crank has been micropolished and cleaned. Rods are Eagle. Can anyone give me any pointers on how to measure for these sizes. I had everything in order such as the main caps paired with the main bearings but got it all from the machine shop in a big bag instead of the 7 i had. Any help will be greatly appreciated thanks!

12-28-2005, 12:27 AM	#2
TONY! 12psi boost Join Date: Sep 2005 Location: Troy, NY 12180 Posts: 353	If I were to build a motor, I would do it myself. The hardest thing about building one is knowing how to get the right clearances. (Many seem to operate on hope.) The TSRM states what you should have for your clearances. Now MY procedure would be to: 1) Have one machine shop mic' up the bores and write it down, and give it to me (I did that already). 2) Go to another machine shop and have the bores mic'ed again to verify and double check the numbers. (It is very important to get this right, so a second measure is worth it to me.) 3) Mic’ my outside diameters (journals). Or you can have the shop do that also if you think you won’t get accurate values. 4) Match up the values (ID’s and OD’s) to these charts: http://www.cygnusx1.net/supra/library/TSRM/em/EM_70.html http://www.cygnusx1.net/supra/library/TSRM/em/EM_73.html 5) Confirm with Jeff Watson and buy from him. Measuring outside diameters is pretty easy (crank journals, cam journals, turbine shafts, pistons, valve shims, valve stems, etc). It is the bores that are extremely hard in comparison (crank tunnels, cam tunnels, turbo cartridges, cylinders, valve guides, etc). __________________ -------------> ITEMS THAT ARE STILL AVAILABLE FROM AN '88 PART OUT <------------- _____\|_____ /. . . \ . . . \ . .\ ( ]/ . . . . \ . . . \ . .\[ ) _________________ /OO]====(W)====[OO\ [___________________] [ [O] ///______\\\ [O]_] ____________________[\|\|]______________[\|\|]____________________ Last edited by TONY!; 12-28-2005 at 12:30 AM.

12-28-2005, 12:51 AM	#4
TONY! 12psi boost Join Date: Sep 2005 Location: Troy, NY 12180 Posts: 353	Your welcome. Just as a mention, as far as I know, the "Select Fit Bearing" system that Toyota uses: that is because of variations in the bores, not the journals, or at least that was my take on it. My crank was perfectly symetrical. The block's main journal bores, however, were all very slightly different. Maybe it is much easier to get an outside diameter uniform than it is to get a series of tunnels one uniform diameter. To accurately measure the bores, a cylinder gauge is required. As seen in this pic: http://www.cygnusx1.net/supra/librar.../em/EM_74.html The one I seen being used had a water level to ensure that the gauge is perfectly perpendicular to the walls. Using T-bore gauges will not be accurate enough. If they do it with a T-bore gauge, I would get nervous. Hope that helps __________________ -------------> ITEMS THAT ARE STILL AVAILABLE FROM AN '88 PART OUT <------------- _____\|_____ /. . . \ . . . \ . .\ ( ]/ . . . . \ . . . \ . .\[ ) _________________ /OO]====(W)====[OO\ [___________________] [ [O] ///______\\\ [O]_] ____________________[\|\|]______________[\|\|]____________________

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12-28-2005, 12:31 AM	#3
Justin727 Stock Join Date: Dec 2005 Posts: 4	nicely written Tony! Thank you!

12-28-2005, 01:43 AM	#5
Justin727 Stock Join Date: Dec 2005 Posts: 4	Thank you agian tony you are a valuable asset to the community its a shame we lost you at sm and sf's. Thanks agian for the help Buddy!