Cranking Bearings

Update by Alan Cesar to the Subaru Impreza WRX project car
Jun 24, 2013

Keep your specs nearby, whether on paper on on a computer.
We used ARP fasteners to hold the whole thing together, case halves and all.
The ACL Race Bearings push in by hand, just like any other.
How much the plastic gets squished tells you how much oil clearance you have.
Once you've confirmed your clearances, you can put together the rotating assembly with confidence—and plenty of assembly lube.
The ARP case bolt kit even comes with replacements for these little guys on the outside of the block.

Checking bearing clearances is one of those processes that, like gapping rings, must be done before the short block is completely assembled.

We grabbed our brand-new crankshaft purchased from and set it next to our engine block as we slotted the ACL Race Bearings into place. We got those bearings from IPG Parts. With the bearings in place, we clipped a bit of PlastiGage (available at your local parts store) and placed it on each bearing.

Then we installed and properly torqued the ARP case bolts according to their instructions using the provided thread lubricant. It helps to lubricate the dowel pins when you do this so you can separate the case halves easily to check those clearances.

Popping the case back apart reveals a squished bit of plastic. With the PlastiGage wrapper, we can determine how much clearance there is for oil between the crank journal and the bearing. The process is the same for connecting rod bearings (and hey, our Manley rods use ARP bolts, too). It’s important that you perform this check and verify that everything’s within spec before assembling the block.

Engines that aren’t a boxer design are easier to check, because you don’t have to lift half an engine block off the other half. All of this can be done on an engine stand with a “traditional” vee or inline engine.

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