Main Bearing Clearance Issues

[blazebolt]

I'm not sure if this is the correct forum. Mods feel free to move to Cylinder Head & Short Block.

I am having clearancing issues on my 2.3L build and need some direction. The block had everything done to it including, .020 Bore/hone, Crankshaft align main bore, slightly used 100mm Eagle Crankshaft balanced and micropolished. I am using ACL Trimetal Race bearings (5M1144H-STD). When I went to measure the main bearing clearance with plastigauge, I am getting .002" on the top and .006" on the bottom (oil pan side/main cap side). I did this 4 times and got the same results. Unfortunately, I don't have access to a micrometer to measure the crankshaft journals or main bore. Is there something that I could be doing wrong? What can I try before taking it back to the machine shop?

Thanks in advance for the advice.

 

[1fast fwd]

Sounds like you need to take it back to the machine who and have the mains rebored and order oversized bearings. Should fix the problem.

 

[TSIfreek]

You are over doing the bearing clearance check. You only put plasti gauge on the cap side of crank then torque it down remove it then check the clearance.
Basicly you put all the bearings in the block end set the crank in with NO lube place the plasi gauge on the crank and then put the cap and bearing on torque it then remove it and there is your clearance. Your shooting for .002-.0025

 

[blazebolt]

You are over doing the bearing clearance check. You only put plasti gauge on the cap side of crank then torque it down remove it then check the clearance.

Yeah that's what I thought, but I did both just to be sure since I had such a big clearance gap on the cap side.

Basicly you put all the bearings in the block end set the crank in with NO lube place the plasi gauge on the crank and then put the cap and bearing on torque it then remove it and there is your clearance. Your shooting for .002-.0025

That's what I did. I thought the clearance spec is .0008"-.002". Is that wrong? So is oversized bearings my best bet? How do I calculate the correct size to use?

 

[donniekak]

Sounds like you need to take it back to the machine who and have the mains rebored and order oversized bearings. Should fix the problem.

Bearings are made for an undersized crank, not bored out mains. When the mains are line honed, the caps are ground down, making the journal smaller. The caps are then torqued onto the block, and honed out to standard size.