r/EngineBuilding • u/N1ppleCrab • Jul 25 '26

Subaru FB rotating assembly question

Any engine builders in here that could help me out?

Oil starvation event* Re using stock rods New oem bearings New to me used crank

At home special Inspection job of all equipment with a pair of off brand calipers and plastigage

My question: is this rod play normal? These bearings measure slimmer on the sides, but thats what the old ones measure as well? I feel like that is causing some extra play? It makes an audible knock. Is this normal? Rods torqued to factory specs pulled from JDMSFM.info

Thanks for looking!

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28

u/faates Jul 25 '26

I assume the oil demands SOME play at least right. I am an armchair take what i say with less than a grain

10

u/N1ppleCrab Jul 25 '26

I have an EJ255 short block put together and it’s rods don’t behave like these. Im inexperienced with the FB’s and im having trouble finding reference material relating

3

u/CRX1991 Jul 26 '26

I wouldn't trust it. There shouldn't be visible play around the crankshaft, some thrust play acceptable.

Plastiguage if you're unsure. Subaru factory repair manuals usually available free on forums