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Searched several threads, found a few helpful posts but most were vague or had responses like "I sent it to the machine shop and they handled it" :sick:

I'm doing a bearing refresh on a high-mileage JDM 2Z for a friend. From what I'm told it ran fine but the engine's new owner wants new bearings before it goes in the car. I assumed they were going to be OEM bearings but was given ACL Race Series bearings, the guy is adamant about using them although it'll probably be just a mild APU setup.


Measurements
Since I couldn't find my micrometers and dial bore gauge I used green plastigauge as per the FSM for preliminary inspection. Seems a little crude/old-school using the stuff but Toyota approves it.

Rod and main bearing clearances were at the plastigauge's .038mm / .0015 inch scale, which falls in the FSM range of .023 - .031 mm / .0009 -.0016 inch standard clearance.

Doing the crank journal # + (OEM) rod # math yielded a "3" bearing for each rod. I like triple-checked the crank markings to be sure, seemed too easy LOL

Wasn't so lucky with the main bearings, 5 x "3" and one each of a "4" and "2"

Why mention the OEM bearing #s when I'll be installing ACLs? Keep reading ;)

Back to the ACL Race bearings (standard size)
Rod bearings "max wall" (assuming ACL's term for bearing center wall thickness) specification is 1.506mm (no inch spec listed); same thickness of a OEM "3" bearing, 1.504 - 1.507mm.

Main bearings "max wall" is 2.004mm; same thickness of a "4" bearing, 2.003 - 2.006mm.

ACL states these bearings "....can be assembled with .00075-.001” per 1” of journal diameter (0.020-0.025mm per 25mm of journal diameter) plus .0005” (0.013mm)"

Using ACL's formula for the rod bearings, they will be beyond OEM bearing clearance range and closer to maximum for standard bearings or standard range for undersize bearings
  • ACL formula for rod bearing clearance = .065 mm / .0025 inch
  • OEM standard .023 - .041 mm / .0009 - .0016 inch
  • OEM maximum .07 mm / .0027 inch
  • OEM undersize .0028 - .066 mm / .001 - .0026 inch
Using the same formula for main bearings, they will be way beyond OEM bearing clearance range for standard and undersize bearings and beyond maximum clearance for standard bearings
  • ACL formula for main bearing clearance = .0750 mm / .00294 inch
  • OEM standard .026 - .040 mm / .0010 - .0016 inch. Max .06 mm / .0024 inch
  • OEM undersize .025 - .061 mm / .0010 - .0024 inch
  • OEM maximum clearance .06 mm / .0024 inch
What clearances then?
Follow ACL's clearance formula and run them looser than OEM specs?

At the moment the calculated rod clearances sound ok, just a little concerned about the mains.

I still need to get my tools together to actually measure the parts. Hopefully I can find my dial indicator so I can measure the thrust clearance.
 
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