USDM crank in JDM - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

azreark1 · 03-08-2015, 06:56 PM

So my JDM SR20 crank was hosed on #3 due to a spun rod bearing, mic'd the crank and it needs to be taken to a machine shop so i picked up a USDM SR20 for dirt cheap so that i could just use the crank out of it and get it back together quick.
My first question is about the balancing of the crank, i know both the JDM and USDM cranks have the same number, but are they balanced differently due to the fact that the USDM rod is smaller than the JDM rod?

Second question is how much does it matter if the connecting rod is out of round? As long as the crank is perfect and the rod is BARELY out of round, will the bearing still ride the crank good? I'm not trying to cut corners here, because my wife would KILL me if i got this back together only to have to tear it back down again in a month due to a failed rod bearing...i'm just curious about the clearances and how bad it would have to be to make it fail again.

GOOD connecting rod measurements are about 2.001 - 2.003 all the way around, bad connecting rod is 2.001 where the halves meet and 2.010 from the bottom of the rod to the top (perpendicular to the connecting faces), Looks like a huge difference to me but i will admit I'm illiterate when it comes to oil clearances.

03-08-2015, 06:56 PM	#1
azreark1 Leaky Injector Join Date: Feb 2015 Location: San Antonio, Tx Age: 40 Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	USDM crank in JDM So my JDM SR20 crank was hosed on #3 due to a spun rod bearing, mic'd the crank and it needs to be taken to a machine shop so i picked up a USDM SR20 for dirt cheap so that i could just use the crank out of it and get it back together quick. My first question is about the balancing of the crank, i know both the JDM and USDM cranks have the same number, but are they balanced differently due to the fact that the USDM rod is smaller than the JDM rod? Second question is how much does it matter if the connecting rod is out of round? As long as the crank is perfect and the rod is BARELY out of round, will the bearing still ride the crank good? I'm not trying to cut corners here, because my wife would KILL me if i got this back together only to have to tear it back down again in a month due to a failed rod bearing...i'm just curious about the clearances and how bad it would have to be to make it fail again. GOOD connecting rod measurements are about 2.001 - 2.003 all the way around, bad connecting rod is 2.001 where the halves meet and 2.010 from the bottom of the rod to the top (perpendicular to the connecting faces), Looks like a huge difference to me but i will admit I'm illiterate when it comes to oil clearances.